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skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 1 data sheet cx72301: spur-free, 1.0 ghz dual fractional-n frequency synthesizer applications ? general purpose rf systems ? low bit rate wireless telemetry ? instrumentation ? specialized mobile radios (smrs) and private mobile radios (pmrs) features ? spur-free operation ? 1.0 ghz maximum operating frequency ? 500 mhz maximum auxiliary synthesizer ? ultra-small step size, 100 hz or less ? high internal reference frequency enables large loop bandwidth implementations ? very fast switching speed (e.g., below 100 s) ? phase noise to C96 dbc/hz inside the loop filter bandwidth @ 950 mhz ? software programmable power-down modes ? high-speed serial interface up to 100 mbps ? three-wire programming ? programmable division ratios on reference frequency ? phase detectors with programmable gain provide a programmable loop bandwidth ? frequency power steering further enhances rapid acquistion time ? on-chip crystal oscillator ? frequency adjust for temperature compensation ? direct digital modulation ? 3 v operation ? 5 v output to loop filter ? 28-pin ep-tssop 6.4 x 9.7 mm package description skyworks cx72301 direct digital modulation fractional-n frequency synthesizer provides ultra-fine frequency resolution, fast switching speed, and low phase-noise performance. this synthesizer is a key building block for high-performance radio system designs that require low power and fine step size. the ultra-fine step size of less than 100 hz allows this synthesizer to be used in very narrowband wireless applications. with proper temperature sensing or through control channels, the synthesizers fine step size can compensate for crystal oscillator or intermediate frequency (if) filter drift. as a result, crystal oscillators or crystals can replace temperature- compensated or ovenized crystal oscillators, reducing parts count and associated component cost. the devices fine step size can also be used for doppler shift corrections. the cx72301 has a phase noise floor of C95 dbc/hz up to 1.0 ghz operation as measured inside the loop bandwidth. this is permitted by the on-chip low noise dividers and low divide ratios provided by the devices high fractionality. reference crystals or oscillators up to 50 mhz can be used with the cx72301. the crystal frequency is divided down by independent programmable divider ratios of 1 to 32 for the main and auxiliary synthesizers. the phase detectors can operate at a maximum speed of 25 mhz, which allows better phase noise due to the lower division value. with a high reference frequency, the loop bandwidths can also be increased. larger loop bandwidths improve the settling times and reduce in-band phase noise. therefore, typical switching times of less than 100 s can be achieved. the lower in-band phase noise also permits the use of lower cost voltage controlled oscillators (vcos) in customer applications. the cx72301 has a frequency power steering circuit that helps the loop filter steer the vco when the frequency is too fast or too slow, further enhancing acquisition time. the unit operates with a three-wire, high-speed serial interface. a combination of a large bandwidth, fine resolution, and the three- wire, high-speed serial interface allows for a direct frequency modulation of the vco. this supports any continuous phase, constant envelope modulation scheme such as frequency modulation (fm), frequency shift keying (fsk), minimum shift keying (msk), or gaussian minimum shift keying (gmsk). this capability can eliminate the need for in-phase and quadrature (i/q) digital-to-analog converters (dacs), quadrature upconverters, and if filters from the transmitter portion of the radio system. figure 1 shows a functional block diagram for the cx72301. the device package and pinout for the 28-pin exposed pad thin shrink small outline package (ep-tssop) are shown in figure 2.
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 2 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h serial interface modulation unit main divider auxiliary divider fvco_aux fvco_aux fvco_main fpd_main fpd_aux fref_main fref_aux fref cpout_aux cpout_main ld/psmain ld/psaux fvco_main reference frequency oscillator reference frequency oscillator main phase/freq. detector and charge pump auxiliary phase/freq. detector and charge pump main divider auxiliary prescaler data mux mod_in mux_out clock cs fractional unit fractional unit ? 18-bit ? 10-bit registers modulator data main divider modulator control ref. divider synth control aux. divider main ? aux. ? lock detection or power steering lock detection or power steering c1447 figure 1. cx72301 functional block diagram c1412 clock mod_in mux_out vsubdigital gndcml vcccml_main fvco_main fvco_main ld/psmain vcccp_main cpout_main gndcp_main xtalacgnd/osc xtalin/osc cs data vccdigital gnddigital vcccml_aux fvco_aux fvco_aux gndcp_aux cpout_aux vcccp_aux ld/psaux gndxtal vccxtal xtalout/nc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 figure 2. cx72301 pinout, 28-pin ep-tssop (top view)
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 3 technical description the cx72301 is a fractional-n frequency synthesizer using a ? modulation technique. the fractional-n implementation provides low in-band noise by having a low division ratio and fast frequency settling time. in addition, the cx72301 provides arbitrarily fine frequency resolution with a digital word, so that the frequency synthesizer can be used to compensate for crystal frequency drift in the rf transceiver. serial interface the serial interface is a versatile three-wire interface consisting of three pins: clock (serial clock), data (serial input), and cs (chip select). it enables the cx72301 to operate in a system where one or multiple masters and slaves are present. to perform a loopback test at start-up and to check the integrity of the board and processor, the serial data is fed back to the master device (e.g., a microcontroller or microprocessor unit) through a programmable multiplexer. this facilitates hardware and software debugging. registers there are ten 16-bit registers in the cx72301. for more information, see the register descriptions section of this document. main and auxiliary ? modulators the fractionality of the cx72301 is accomplished by the use of a proprietary, configurable 10-bit or 18-bit ? modulator for the main synthesizer and 10-bit ? modulator for the auxiliary synthesizer. main and auxiliary fractional units the cx72301 provides fractionality through the use of main and auxiliary ? modulators. the output from the modulators is combined with the main and auxiliary divider ratios through their respective fractional units. vco prescalers the vco prescalers provide low-noise signal conditioning of the vco signals. they translate from an off-chip, single-ended or differential signal to an on-chip differential current mode logic (cml) signal. the cx72301 has independent main and auxiliary vco prescalers. main and auxiliary vco dividers the cx72301 provides programmable dividers that control the cml prescalers and supply the required signals to the charge pump phase detectors. programmable divide ratios ranging from 38 to 537 are possible in fractional-n mode and from 32 to 543 in integer-n mode. reference frequency oscillator the cx72301 has a self-contained, low-noise crystal oscillator. this crystal oscillator is followed by the clock generation circuitry that generates the required clock for the programmable reference frequency dividers. reference frequency dividers the crystal oscillator signal can be divided by a ratio of 1 to 32 to create the reference frequencies for the phase detectors. the cx72301 has both a main and an auxiliary frequency synthesizer, and provides independently configurable dividers of the crystal oscillator frequency for both the main and auxiliary phase detectors. the divide ratios are programmed through the reference frequency dividers register. note : the divided crystal oscillator frequencies (which are the internal reference frequencies), fref_main and fref_aux, are referred to as the reference frequencies throughout this document. phase detectors and charge pumps the cx72301 uses a separate charge pump phase detector for each synthesizer which provides a programmable gain, kd , from 31.25 to 1000 a/2 radians in 32 steps programmed using the control register. frequency steering when programmed for frequency power steering, the cx72301 has a circuit that helps the loop filter steer the vco using the ld/psmain signal (pin 9). in this configuration, the ld/psmain signal can provide a more rapid acquisition. when programmed for lock detection, internal frequency steering is implemented and provides frequency acquisition times comparable to conventional phase/frequency detectors. lock detection when programmed for lock detection, the cx72301 provides an active low, pulsing open collector output using the ld/psmain signal (pin 9) to indicate the out-of-lock condition. when locked, the ld/psmain signal is three-stated (high impedance). power down the cx72301 supports a number of power-down modes through the serial interface. for more information, see the register descriptions section of this document.
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 4 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h operation this section describes the operation of the cx72301. the serial interface is described first, followed by information on how to obtain values for the divide ratio registers. serial interface the serial interface consists of three signals: clock (pin 1), data (pin 27) and cs (pin 28). the clock signal controls data on the two serial data lines (data and cs). the data pin bits shift into a temporary register on the rising edge of clock. the cs line allows individual selection transfers that synchronize and sample the information of slave devices on the same bus. figure 3 functionally depicts how a serial transfer takes place. a serial transfer is initiated when a microcontroller or microprocessor forces the cs line to a low state. this is followed immediately by an address/data stream sent to the data pin that coincides with the rising edges of the clock presented on the clock line. each rising edge of the clock signal shifts in one bit of data on the data line into a shift register. at the same time, one bit of data is shifted out of the mux_out pin (if the serial bit stream is selected) at each falling edge of clock. to load any of the synthesizer registers, 16 bits of address or data must be presented to the data line with the data lsb last while cs is low. if cs is low for more than 16 clock cycles, only the last address or data bits are used to load the synthesizer registers. if the cs line is brought to a high state before the 13 th clock edge on clock, the bit stream is assumed to be modulation data samples. in this case, it is assumed that no address bits are present and that all the bits in the stream should be loaded into the modulation data register. synthesizer register programming synthesizer register programming equations, described in this section, use the following variables and constants: n fractional desired vco division ratio in fractional-n applications. this is a real number and can be interpreted as the reference frequency ( f ref ) multiplying factor such that the resulting frequency is equal to the desired vco frequency. n integer desired vco division ratio in integer-n applications. this number is an integer and can be interpreted as the reference frequency ( f ref ) multiplying factor so that the resulting frequency is equal to the desired vco frequency. n reg 9-bit unsigned input value to the divider ranging from 0 to 511 (integer-n mode) and from 6 to 505 (fractional-n mode). divider this constant equals 262144 when the ? modulator is in 18-bit mode, and 1024 when the ? modulator is in 10-bit mode. dividend when in 18-bit mode, this is the 18-bit signed input value to the ? modulator, ranging from C131072 to +131071 and providing 262144 steps, each of f div_ref /2 18 hz. when in 10-bit mode, this is the 10-bit signed input value to the ? modulator, ranging from C512 to +511 and providing 1024 steps, each of fdiv_ref /2 10 hz. f vco desired vco frequency (either f vco_main or f vco_aux ). f div_ref divided reference frequency presented to the phase detector (either f ref_main or f ref_aux ). x a3 a2 a1 a0 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 xxx clock last data cs c1413 figure 3. serial transfer timing diagram
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 5 fractional-n applications . the desired division ratio for the main and auxiliary synthesizer is given by the following equation: n fractional f vco f div _ ref ------------------- = where n fractional must be between 37.5 and 537.5. the value to be programmed in the main or auxiliary divider register is given by the equation: n reg round n fractional 32 ? = note : the round function rounds the number to the nearest integer. when in fractional mode, allowed values for n reg are from 6 to 505, inclusive. the value to be programmed in the main or auxiliary dividend register is given by the following equation: dividend round divider n fractional n reg 32 ? ? = where the divider is either 1024 in 10-bit mode or 262144 in 18-bit mode. therefore, the dividend is a signed binary value either 10 or 18 bits long. note : because of the high fractionality of the cx72301, there is no practical need for any integer relationship between the reference frequency and the channel spacing or desired vco frequencies. sample calculations for two fractional-n applications are provided in figure 4. case 1 : to achieve a desired f vco_main frequency of 902.4530 mhz using a crystal frequency of 40 mhz with operation of the synthesizer in 18-bit mode. since the maximum internal reference frequency (f div_ref ) is 25 mhz, the crystal frequency is divided by 2 to obtain a f div_ref of 20 mhz. therefore: n fractional =f vco_main f div_ref = 902.4530 20 = 45.12265 the value to be programmed in the main divider register is: n reg = round[n fractional ] ? 32 = round[45.12265] ? 32 = 45 ? 32 = 13 (decimal) = 000001101 (binary) with the modulator in 18-bit mode, the value to be programmed in the main dividend registers is: dividend = round[divider (n fractional ? n reg ? 32)] = round[262144 (45.12265 ? 13 ? 32)] = round[262144 (0.12265)] = round[32151.9616] = 32152 (decimal) = 000111110110011000 (binary) where 00 0111 1101 is loaded in the msb of the main dividend register and 1001 1000 is loaded in the lsb of the main dividend register. summary: main divider register = 0 0000 1101 main dividend lsb register = 1001 1000 main dividend msb register = 00 0111 1101 the resulting main vco frequency is 902.453 mhz step size is 76.3 hz note: the frequency step size for this case is 20 mhz divided by 2 18 , giving 76.3 hz. c1414 figure 4. fractional-n applications: sample calculation (1 of 2)
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 6 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h case 2 : to achieve a desired f vco_main frequency of 917.7786 mhz using a crystal frequency of 19.2 mhz with operation of the synthesizer in 10-bit mode. since the maximum internal reference frequency (f div_ref ) is 25 mhz, the crystal frequency does not require the internal division to be greater than 1, which makes f div_ref = 19.2 mhz. therefore: n fractional =f vco_main f div_ref = 917.7786 19.2 = 47.80097 the value to be programmed in the main divider register is: n reg = round[n fractional ] ? 32 = round[47.80097] ? 32 = 48 ? 32 = 16 (decimal) = 000010000 (binary) with the modulator in 10-bit mode, the value to be programmed in the main dividend registers is: dividend = round[divider (n fractional ? n reg ? 32)] = round[1024 (47.80097 ? 16 ? 32)] = round[1024 (? 0.1990312)] = round[? 203.808] = 204 (decimal) = 1100110100 (binary) where 11 0011 0100 is loaded in the msb of the main dividend register. summary: main divider register = 0 0001 0000 main dividend msb register = 11 0011 0100 the resulting main vco frequency is 917.775 mhz step size is 18.75 khz note: the frequency step size for this case is 19.2 mhz divided by 2 10 , giving 18.75 khz. c1415 figure 4. fractional-n applications: sample calculation (2 of 2) integer-n applications . the desired division ratio for the main or auxiliary synthesizer is given by: n integer f vco _ main f div _ ref --------------------------- - = where n integer is an integer number from 32 to 543 for both the main and auxiliary synthesizers. the value to be programmed in the main or auxiliary divider register is given by the following equation: n reg f integer 32 ? = when in integer mode, allowed values for n reg are from 0 to 511 for both the main and auxiliary synthesizers. note : as with all integer-n synthesizers, the minimum step size is related to the crystal frequency and reference frequency division ratio. a sample calculation for an integer-n application is provided in figure 5. register loading order . in applications where the main synthesizer is in 18-bit mode, the main dividend msb register holds the 10 msbs of the dividend and the main dividend lsb register holds the 8 lsbs of the dividend. the registers that control the main synthesizers divide ratio are to be loaded in the following order: ? main divider register ? main dividend lsb register ? main dividend msb register (at which point the new divide ratio takes effect)
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 7 to achieve a desired f vco_aux frequency of 400 mhz using a crystal frequency of 16 mhz. since the minimum divide ratio is 32, the reference frequency (f div_ref ) must be a maximum of 12.5 mhz. choosing a reference frequency divide ratio of 2 provides a reference frequency of 8 mhz. therefore: n integer =f vco_aux f div_ref = 400 8 =50 the value to be programmed in the auxiliary divider register is: n reg =n integer ? 32 = 50 ? 32 = 18 (decimal) = 000010010 (binary) summary: auxiliary divide register = 0 0001 0010 c1416 figure 5. integer-n applications: sample calculation in applications where the main synthesizer is in 10-bit mode, the main dividend register holds the 10 bits of the dividend. the registers that control the main synthesizers divide ratio are to be loaded in the following order: ? main divider register ? main dividend msb register (at which point the new divide ratio takes effect) for the auxiliary synthesizer, the auxiliary dividend register holds the 10 bits of the dividend. the registers that control the auxiliary synthesizers divide ratio are to be loaded in the following order: ? auxiliary divider register ? auxiliary dividend register (at which point the new divide ratio takes effect) note : when in integer mode, the new divide ratios take effect when the main or auxiliary divider register is loaded. direct digital modulation the high fractionality and small step size of the cx72301 allow the vco to be tuned to practically any frequency in the vcos operating range. this frequency tuning allows direct digital modulation by programming the different desired frequencies at precise instants. typically, the channel frequency is selected through the main divider and dividend register and the instantaneous frequency offset from the carrier is entered through the modulation data register. the modulation data register can be accessed in three ways, which are defined in the following subsections. normal register write . a normal 16-bit serial interface write occurs when cs is 16 clock cycles wide. the corresponding 16-bit modulation data is simultaneously presented to the data pin. the content of the modulation data register is passed to the modulation unit at the next falling edge of the divided main vco frequency ( f pd_main ). short cs through data pin (no address bits required) . a shortened serial interface write occurs when cs is 16 clock cycles wide. the corresponding modulation data (2 to 12 bits) is simultaneously presented to the data pin. the data pin is the default pin used to enter modulation data directly into the modulation data register with shortened cs strobes. this method of data entry eliminates the register address overhead on the serial interface. all serial interface bits are re-synchronized internally at the reference oscillator frequency. the content of the modulation data register is passed to the modulation unit at the next falling edge of the divided main vco frequency ( f pd_main ). short cs through mod_in pin (no address bits required) . a shortened serial interface write where cs is from 2 to 12 clock cycles wide and modulation data (2 to 12 bits) is presented on the mod_in pin. the mod_in pin is the alternate pin used to enter modulation data directly into the modulation data register with shortened cs strobes. this mode is selected through the modulation control register. this method of data entry also eliminates the register address overhead on the serial interface and allows a different device than the one controlling the channel selection to enter the modulation data (e.g., a microcontroller for channel selection and a digital signal processor for modulation data). all serial interface bits are re-synchronized internally at the reference oscillator frequency and the content of the modulation data register is passed to the modulation unit at the next falling edge of the divided main vco frequency ( f pd_main ).
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 8 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h modulation data samples in the modulation data register can be from 2 to 12 bits long, and enable the user to select how many distinct frequency steps are to be used for the desired modulation scheme. the user can also control the frequency deviation through the modulation data magnitude offset in the modulation control register. this allows shifting of the modulation data to accomplish a 2 m multiplication of frequency deviation. note : the programmable range of C0.5 to +0.5 of the main ? modulator can be exceeded up to the condition where the sum of the dividend and the modulation data conform to the following relationship: - 0.5625 n mod dividend + 0.5625 when the sum of the dividend and modulation data lie outside this range, the value of n integer must be changed. for a more detailed description of direct digital modulation functionality, refer to the skyworks application note, direct digital modulation using the cx72300, cx72301, and cx72302 dual synthesizers/plls (document number 101349). register descriptions this section describes the cx72301 registers. all register writes are programmed address first, followed directly with data. msbs are entered first. on power-up, all registers are reset to 0x000 except registers at address 0x0 and 0x3, which are set to 0x006. table 1 provides a description for each of the cx72301 device registers. for more information on register loading, refer to the synthesizer register programming section in this document. synthesizer registers main synthesizer registers . the main divider register contains the integer portion closest to the desired fractional-n (or the integer-n) value minus 32 for the main synthesizer. this register, in conjunction with the main dividend registers (which control the fraction offset from C0.5 to +0.5), allows selection of a precise frequency. as shown in figure 6, the value to be loaded is: ? main synthesizer divider index = 9-bit value for the integer portion of the main synthesizer dividers. valid values for this register are from 6 to 505 (fractional-n) or 0 to 511 (integer-n). the main dividend msb and lsb registers control the fraction part of the desired fractional-n value and allow an offset of C0.5 to + 0.5 to the main integer selected through the main divider register. as shown in figures 7 and 8, values to be loaded are: ? main synthesizer dividend (msbs) = 10-bit value for the msbs of the 18-bit dividend for the main synthesizer. ? main synthesizer dividend (lsbs) = 8-bit value for the lsbs of the 18-bit dividend for the main synthesizer. the main dividend msb and lsb register values are 2's complement format. note : when in 10-bit mode, the main synthesizer dividend (lsbs) is not required. for information on programming and loading order for these registers, see the operation section of this document. table 1. cx72301 register map address (hex) register (note 1) length (bits) address (bits) 0 main divider register 12 4 1 main dividend msb register 12 4 2 main dividend lsb register 12 4 3 auxiliary divider register 12 4 4 auxiliary dividend register 12 4 5 reference frequency dividers register 12 4 6 control registerphase detector/charge pumps 12 4 7 control registerpower down/m ultiplexer output select 12 4 8 modulation control register 12 4 9 modulation data register modulation data register (note 2) direct input 12 2 length 12 bits 4 0 note 1 : all registers are write only. note 2 : no address bits are required for modulation data. any serial data between 2 and 12 bits long is considered modulation data.
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 9 a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 0000xxx msb lsb main synthesizer divider index c1417 figure 6. main divider register (write only) c1418 a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 0001xx msb lsb main synthesizer dividend (msbs) figure 7. main dividend msb register (write only) a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 0010xxxx msb lsb main synthesizer dividend (lsbs) c1419 figure 8. main dividend lsb register (write only) auxiliary synthesizer registers . the auxiliary divider register contains the integer portion closest to the desired fractional-n (or integer-n) value minus 32 for the auxiliary synthesizer. this register, in conjunction with the auxiliary dividend register, which controls the fraction offset (from C0.5 to + 0.5) allows selection of a precise frequency. as shown in figure 9, the value to be loaded is: ? auxiliary synthesizer divider index = 9-bit value for the integer portion of the auxiliary synthesizer dividers. valid values for this register are from 6 to 505 (fractional-n) or from 0 to 511 (integer-n). the auxiliary dividend register controls the fraction part of the desired fractional-n value and allows an offset of C0.5 to + 0.5 to the auxiliary integer selected through the auxiliary divider register. as shown in figure 10, the value to be loaded is: ? auxiliary synthesizer dividend = 10-bit value for the dividend for the auxiliary synthesizer. for information on programming and loading order for these registers, see the operation section of this document. general synthesizer registers . the reference frequency dividers register configures the dual-programmable reference frequency dividers for the main and auxiliary synthesizers. the dual-programmable reference frequency dividers provide the reference frequencies to the phase detectors by dividing the crystal oscillator frequency. the lower five bits hold the reference frequency divide index for the main phase detector. the next five bits hold the reference frequency divide index for the auxiliary phase detector. divide ratios from 1 to 32 are possible for each reference frequency divider (see tables 2 and 3). as shown in figure 11, the values to be loaded are: ? main reference frequency divider index = desired main oscillator frequency division ratio C 1. default value on power- up is 0, signifying that the reference frequency is not divided for the main phase detector. ? auxiliary reference frequency divider index = desired auxiliary oscillator frequency division ratio C 1. default value on power-
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 10 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h up is 0, signifying that the reference frequency is not divided for the auxiliary phase detector. the control register allows control of the gain for both phase detectors and configuration of the ld/psmain and ld/psaux pins for frequency power steering or lock detection. as shown in figure 12, the values to be loaded are: ? main phase detector gain = 5-bit value for programmable main phase detector gain. range is from 0 to 31 decimal for 31.25 to 1000 a/2 radian, respectively. ? main power steering enable = 1-bit value to enable the frequency power steering circuitry of the main phase detector. when this bit is a 0, the ld/psmain pin is configured to be a lock detect, active-low, open collector pin. when this bit is a 1, the ld/psmain pin is configured to be a frequency power steering pin and can be used to bypass the external main loop filter to provide faster frequency acquisition. ? auxiliary phase detector gain = 5-bit value for programmable auxiliary phase detector gain. range is from 0 to 31 decimal for 31.25 to 1000 a/2 radian, respectively. ? auxiliary power steering enable = 1-bit value to enable the frequency power steering circuitry of the auxiliary phase detector. when this bit is a 0, the ld/psaux pin is configured to be a lock detect, active-low, open collector pin. when this bit is a 1, the ld/psaux pin is configured to be a frequency power steering pin and may be used to bypass the external auxiliary loop filter to provide faster frequency acquisition. a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 0011xxx msb lsb auxiliary synthesizer divider index c1420 figure 9. auxiliary divider register (write only) a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 0100xx msb lsb auxiliary synthesizer dividend c1421 figure 10. auxiliary dividend register (write only) table 2. programming the main reference frequency divider decimal bit 4 (msb) bit 3 bit 2 bit 1 bit 0 (lsb) reference divider ratio 0 0 0 0 0 0 1 1 0 0 0 0 1 2 2 0 0 0 1 0 3 31 1 1 1 1 1 32
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 11 table 3. programming the auxiliary reference frequency divider decimal bit 9 (msb) bit 8 bit 7 bit 6 bit 5 (lsb) reference divider ratio 0 0 0 0 0 0 1 1 0 0 0 0 1 2 2 0 0 0 1 0 3 31 1 1 1 1 1 32 a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 0101xx main reference frequency divider index auxiliary reference frequency divider index c1422 figure 11. reference frequency divi ders register (write only) a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 0110 main phase detector gain main power steering/lock detect enable auxiliary phase detector gain auxiliary power steering/lock detect enable c1423 figure 12. control register (write only) the power down and multiplexer output register allows control of the power-down modes, internal multiplexer output, and main ? synthesizer fractionality. as shown in figure 13, the values to be loaded are: ? full power-down = 1-bit value that powers down the cx72301 except for the reference oscillator and the serial interface. when this bit is 0, the cx72301 is powered up. when this bit is 1, the cx72301 is in full power-down mode excluding the mux_out pin. ? main synthesizer power-down = 1-bit value that powers down the main synthesizer. when this bit is 0, the main synthesizer is powered up. when this bit is 1, the main synthesizer is in power-down mode. ? main synthesizer mode = 1-bit value that powers down the main synthesizers ? modulator and fractional unit to operate as an integer-n synthesizer. when this bit is 0, the main synthesizer is in a fractional-n mode. when this bit is 1, the main synthesizer is in integer-n mode. ? main synthesizer ? fractionality = 1-bit value that configures the size of the main ? modulator. this has a direct effect on power consumption and on the level of fractionality and step size. when this bit is 0, the main ? modulator is 18-bit with a fractionality of 2 18 and a step size of f ref_main /262144. when this bit is 1, the main ? modulator is 10-bit with a fractionality of 2 10 and a step size of f ref_main /1024.
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 12 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h ? auxiliary synthesizer power down = 1-bit value that powers down the auxiliary synthesizer. when this bit is 0, the auxiliary synthesizer is powered up. when this bit is 1, the auxiliary synthesizer is in power-down mode. ? auxiliary synthesizer mode = 1-bit value that powers down the auxiliary synthesizers ? modulator and fractional unit to operate as an integer-n synthesizer. when this bit is 0, the auxiliary synthesizer is in fractional-n mode. when this bit is 1, the auxiliary synthesizer is in integer-n mode. note : there are no special power-up sequences required for the cx72301. ? multiplexer output selection = 3-bit value that selects which internal signal is output to the mux_out pin. internal signals available on this pin are the following: ? reference oscillator, f ref ? main or auxiliary divided reference (post reference frequency main or auxiliary dividers), f ref_main or f ref_aux ? main or auxiliary phase detector frequency (post main and auxiliary frequency dividers), f pd_main or f pd_aux ? serial data out, for loop-back and test purposes see table 4 for more information. ? mux_out pin three-state enable = 1-bit value to three-state the mux_out pin. when this bit is 0, the mux_out pin is enabled. when this bit is 1, the mux_out pin is three-stated. a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 0111xx msb lsb full power down main synthesizer power down main synthesizer mode main synthesizer ? fractionality auxiliary synthesizer power down auxiliary synthesizer mode multiplexer output selection mux_out pin three-state enable c1424 figure 13. power down and multiplexer output register (write only) table 4. multiplexer output multiplexer output select (bit 8) multiplexer output select (bit 7) multiplexer output select (bit 6) multiplexer output (mux_out) 0 0 0 reference oscillator 0 0 1 auxiliary reference frequency ( f ref_aux ) 0 1 0 main reference frequency ( f ref_main ) 0 1 1 auxiliary phase detector frequency ( f pd_aux ) 1 0 0 main phase detector frequency ( f pd_main ) 1 0 1 serial data out 1 1 0 serial interface register test output
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 13 the modulation control register is used to configure the modulation unit of the main synthesizer. the modulation unit adds or subtracts a frequency offset to the selected center frequency at which the main synthesizer operates. the size of the modulation data sample, controlled by the duration of the cs signal, can be from 2 to 12 bits wide, to provide from 4 to 4096 selectable frequency offset steps. the modulation data magnitude offset selects the magnitude multiplier for the modulation data and can be from 0 to 8. as shown in figure 14, the values to be loaded are: ? modulation data magnitude offset = 4-bit value that indicates the magnitude multiplier ( m ) for the modulation data samples. valid values range from 0 to 13, effectively providing a 2 m multiplication of the modulation data sample. ? modulation data input select = 1-bit value that indicates the pin on which modulation data samples are serially input when the cs signal is between 2 and 12 bits long. when this bit is 0, modulation data samples are to be presented on the data pin. when this bit is 1, modulation data samples are to be presented on the mod_in pin. ? modulation address disable = 1-bit value that indicates the presence of the address as modulation data samples are presented on either the mod_in or data pins. when this bit is 0, the address is presented with the modulation data samples (i.e., all transfers are 16 bits long). when this bit is 1, no address is presented with the modulation data samples (i.e., all transfers are 2 to 12 bits long). the modulation data register is used to load the modulation data samples to the modulation unit. this value is transferred to the modulation unit on the falling edge of f pd_main where it is passed to the main ? modulator at the selected magnitude offset on the next falling edge of f pd_main . modulation data register values are 2's complement format. as shown in figure 15, the value to be loaded is: ? modulation data bits = modulation data samples that represent the desired instantaneous frequency offset to the selected main synthesizer frequency (selected channel) before being affected by the modulation data magnitude offset. a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 1 0 0 0 0 000xx reserved bits modulation data magnitude offset modulation data input select modulation address disable c1425 figure 14. modulation control register (write only) a3 a2 a1 a0 11 10 9 8 7 6 5 4 3 2 1 0 1001 msb lsb modulation data bits c1426 figure 15. modulation data register (write only)
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 14 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h electrical and mechanical specifications the cx72301 is supplied as a 28-pin ep-tssop. the exposed pad is located on the bottom side of the package and must be connected to ground for proper operation. the exposed pad should be soldered directly to the circuit board. signal pin assignments and functional pin descriptions are specified in table 5. the absolute maximum ratings of the cx72301 are provided in table 6. the recommended operating conditions are specified in table 7 and electrical specifications are provided in table 8. figure 16 provides a schematic diagram for the cx72301. figure 17 shows the package dimensions for the 28-pin ep-tssop and figure 18 provides the tape and reel dimensions. electrostatic discharge (esd) sensitivity the cx72301 is a static-sensitive electronic device. do not operate or store near strong electrostatic fields. take proper esd precautions. table 5. cx72301 signal descriptions (1 of 2) pin # pin name type description 1 clock digital input clock signal pin. when cs is low, the regist er address and data are shifted in address bits first on the data pin on the rising edge of clock. 2 mod_in digital input alternate serial modulation data input pin. address bits are followed by data bits. 3 mux_out digital output internal multiplexer output. selects from oscillator fre quency, main or auxiliary reference frequency, main or auxiliary divided vco frequency, serial data out, or testability signals. this pin can be three-stated from the general synthesizer registers. 4 vsubdigital C substrate isolation. connect to ground. 5 gndecl/cml (note 1) power and ground emitter coupl ed logic (ecl)/current mode logic (cml) ground. 6 vcccml_main (note 1) power and ground ecl/cml 3 v. removing power safely powers down the associated divider chain and charge pump. 7 fvco_main input main vco differential input. 8 fvco_main input main vco complimentary differential input. 9 ld/psmain analog output programmable output pin. indicates ma in phase detector out-of-lock as an active low pulsing open collector output (high impedance when lock is detected), or helps the loop filter steer the main vco. this pin is configured from the general synthesizer registers. 10 vcccp_main (note 1) power and ground main charge pump 3 to 5 v. removing powe r safely powers down the associated divider chain and charge pump. 11 cpout_main analog output main charge pump output. the gain of the main charge pump phase detector can be controlled from the general synthesizer registers. 12 gndcp_main (note 1) power and ground main charge pump ground. 13 xtalacgnd/osc ground/input refere nce crystal ac ground or external oscillator differential input. 14 xtalin/osc input reference crystal input or external oscillator differential input. 15 xtalout/nc input reference crystal output or no connect. 16 vccxtal power and ground crystal oscillator ecl/cml 3 v. 17 gndxtal power and ground crystal oscillator ground. 18 ld/psaux analog output programma ble output pin. indicates auxiliary phase dete ctor out-of-lock as an active low pulsing open collector output (high impedance when lock is detected), or helps the loop filter steer the auxiliary vco. this pin is configured from the general synthesizer registers. 19 vcccp_aux (note 1) power and ground auxilia ry charge pump 3 to 5 v. removing power sa fely powers down the associated divider chain and charge pump. 20 cpout_aux analog output auxilia ry charge pump output. the gain of the auxiliary charge pump pha se detector can be controlled from the general synthesizer registers.
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 15 table 5. cx72301 signal descriptions (2 of 2) pin # pin name type description 21 gndcp_aux (note 1) power and gr ound auxiliary charge pump ground. 22 fvco_aux input auxiliary vco complimentary differential input. 23 fvco_aux input auxiliary vco differential input. 24 vcccml_aux (note 1) power and ground ecl/cml 3 v. removing power safely powers down the associated divider chain and charge pump. 25 gnddigital (note 1) power and ground digital ground. 26 vccdigital (note 1) power and ground digital 3 v. 27 data digital input serial address and data input pin. address bits are followed by data bits. 28 cs digital input active low enable pin. enables loading of address and data on th e data pin on the rising edge of clock. when cs goes high, data is transferred to the regist er indicated by the address. subsequent clock edges are ignored. note 1 : associated pairs of power and gro und pins must be decoupled using 0.1 f capacitors. table 6. absolute maximum ratings parameter min max units maximum analog rf supply voltage 3.6 vdc maximum digital supply voltage 3.6 vdc maximum charge pump supply voltage 5.25 vdc storage temperature C65 +150 c operating temperat ure C40 +85 c note : exposure to maximum rating conditions for extended periods may reduce device reliability. there is no damage to device with o nly one parameter set at the limit and all other parameters set at or below their nominal values. table 7. recommended operating conditions parameter min max units analog rf supplies 2.7 3.3 vdc digital supply 2.7 3.3 vdc charge pump supplies 2.7 5.0 vdc operating temperature (t a ) C40 +85 c
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 16 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h table 8. electrical characteristics (1 of 2) (vdd = 3 v, t a = 25 c, unless otherwise noted) parameter symbol test co nditions min typ max units power consumption charge pump currents of 200 a. both synthesizers fractional, f ref _ main = 20 mhz, f ref _ aux = 1 mhz 33 mw total power consumption p total auxiliary synthesizer power down 23 mw power-down current i cc - pwdn 10 (note 1) a reference oscillator reference oscillator frequency f osc 50 mhz oscillator sensitivity (as a buffer) v osc ac coupled, single-ended 0.1 2.0 vpp frequency shift versus supply voltage f shift _ supply 2.7 v v xtal 3.3 v 0.3 ppm vcos main synthesizer operating frequency f vco _ main sinusoidal, C40 c to +85 c 100 (note 2) 1000 mhz auxiliary synthesizer operating frequency f vco _ aux sinusoidal, C40 c to +85 c 100 (note 2) 500 mhz rf input sensitivity v vco ac coupled, C40 c to +85 c 50 250 mv peak rf input impedance z vco _ in 150 C j168 @ 800 mhz ? main fractional-n tuning step size ? f step _ main f ref _ main /2 18 or f ref _ main /2 10 hz auxiliary fractional-n tuning step size ? f step _ aux f ref _ aux /2 10 hz noise phase noise floor p nf measured inside the loop bandwidth using 25 mhz reference frequency, C40 c to +85 c C130 + 20 log (n) dbc/hz phase detectors and charge pumps main phase detector frequency f ref _ main C40 c to +85 c 25 mhz auxiliary phase detector frequency f ref _ aux C40 c to +85 c 25 mhz charge pump output source current i cp - source v cp = 0.5 vcc cp 125 1000 a charge pump output sink current i cp - sink v cp = 0.5 vcc cp C125 C1000 a charge pump accuracy i cp - accuracy 20 % charge pump output voltage linearity range i cp vs v cp 0.5 v v cp (vcc cp C 0.5 v) gnd + 400 vcc cp C 400 mv charge pump current versus temperature i cp vs t v cp = 0.5 vcc cp C40 c < t < +85 c 5 % charge pump current versus voltage i cp vs v cp 0.5 v v cp (vcc cp C 0.5 v) 8 %
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 17 table 8. electrical characteristics (2 of 2) (vdd = 3 v, t a = 25 c, unless otherwise noted) parameter symbol test co nditions min typ max units digital pins high level input voltage v ih 0.7 v digital v low level input voltage v il 0.3 v digital v high level output voltage v oh i oh = C2 ma v digital C0.2 v low level output voltage v ol i ol = +2 ma gnd + 0.2 v timing C serial interface clock frequency f clock 100 mhz data and cs set up time to clock rising t su 3 ns data and cs hold time after clock rising t hold 0 ns note 1: a 5 v charge pump power supply (on pin 10 and/or pin 19) results in higher power-down leakage current. note 2 : the minimum synthesizer frequency is 12 x f osc , where f osc is the frequency at the xtalin/osc pin.
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 18 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h clock mod_in mux_out vsubdigital gndecl/cml vcccml_main fvco_main fvco_main ld/psmain vcccp_main cpout_main gndcp_main xtalacgnd/osc xtalin/osc cs data vccdigital gnddigital vcccml_aux fvco_aux fvco_aux gndcp_aux cpout_aux vcccp_aux ld/psaux gndxtal vccxtal xtalout/nc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 1 9 18 17 16 15 gnd 2 9 to microprocessor 3 v 3 v 3 v vcc 3 v 3 v 3 v 3 v 3 v c5 c7 1 1 5 4 4 3 3 2 2 rf out main j1 1 1 5 4 4 3 3 2 2 rf out auxiliary j1 main vco y1 main synthesizer loop filter auxiliary synthesizer loop filter auxiliary vco auxiliary vco external pad connection to ground gnd vcc c14 r4 r6 100 k ? r5 c15 c8 gnd vt vcc rfout c12 c 9 c4 c6 r3 r2 c1 9 c18 c17 c17 1 nf vcc rfout vt lock detect main output lock detect auxiliar y out p ut a a a a a a a a aa a a c10 1 nf a a a a a a a a a aa a r1 100 k ? c3 1 nf c11 1 nf c2 1 nf c1 1 nf c16 100 pf c1427 figure 16. cx72301 application schematic
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 101090h ? skyworks proprietary and confiden tial information ? products and produc t information are subject to change witho ut notice ? july 21, 2004 19 0.25 +0.5/?0.6 0.65 bsc 9 .70 bsc 1.10 5.50 6.40 bsc 4.4 0.10 0. 9 0 0.05 0.60 0.10 0.10 0.05 3.00 top view side view exposed pad bottom view c142 8 all measurements are in millimeters pin 1 figure 17. cx72301 28-pin ep-tsso p package dimensions 0.318 0.013 1.10 3. 9 6 6.75 0.10 8 o max 7 o max 1.60 0.10 9 . 9 5 0.10 1.50 0.25 16.00 +0.30/?0.10 7.50 0.10 8.00 0.10 4.00 0.10 2.00 0.05 1.75 0.10 1.50 0.10 pin #1 notes: 1. carrier tape material: black conductive polycarbonate or polystyrene 2. cover tape material: transparent conductive psa 3. cover tape size: 13.3 mm width 4. all measurements are in millimeters c1430 ab a b b a figure 18. cx72301 tape and reel dimensions
data sheet ? cx72301 skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@sk yworksinc.com ? www.skyworksinc.com 20 july 21, 2004 ? skyworks proprietary and confidential information ? products a nd product information are subject to change without notice ? 101090h ordering information model name manufacturing part numb er evaluation kit part number cx72301 frequency synthesizer CX72301-11 ph00-d102 copyright ? 2001, 2002, 2004, skyworks solutions, inc. all rights reserved. information in this document is provided in connection with skyw orks solutions, inc. (skywork s) products. these materials are provided by skyworks as a serv ice to its customers and may be used for informational purposes only by the customer. skyworks assumes no responsibilit y for errors or omissions in these mater ials. skyworks may make changes to its documentation, products, specifications and product descriptions at any time, without notice. skyworks makes no commitment to update the information and shall have no responsibilit y whatsoever for conflicts, incompatibilities, or other difficulties aris ing from future changes to its documentat ion, products, specif ications and product descriptions. no license, express or implied, by estoppel or otherwise, to an y intellectual property rights is granted by or under this docum ent. except as may be provided in skyworks terms and conditions of sale for such products, skyworks assumes no liability whatsoever in association with its documentation, products, specification s and product descriptions. these materials are provided as is without warranty of any ki nd, either express or implied or otherwise, relating to sale and /or use of skyworks products including warranties relating to fitness for a particular purpos e, merchantability, performance, quality or non-infringement of any patent, copyright or other intellectual property right. skyworks further does not warrant the accuracy or completeness of the information, text, graphics or other items contained within these materials. skyworks shall not be liable for any damages, in cluding special, indirect, inci dental, or consequential damage s, including without limitation, lost revenues or lost profits that may result from the use of these materials whether or not the recipien t of materials has been adv ised of the possibility of such damage. skyworks products are no t intended for use in medical, lifesaving or life-su staining applications. skyw orks customers using or selling skyworks products for use in such applications do so at their own risk and agree to fully indemnify skyworks for an y damages resulting from such improper use or sale. the following are trademarks of skyworks solutions, inc.: skyworks?, the skyw orks logo, and breakthro ugh simplicity?. product n ames or services listed in this publication are for identification purposes only, and may be trademarks of skyw orks or other third parties. third-party br ands and names are the property of their respective owners. addition al information, posted at www.skyworksinc.com, is incorporated by reference.

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