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SL1925 satellite zero if qpsk tuner ic preliminary information description the SL1925 is a wideband quadrature converter operating from 950 to 2150 mhz, intended primarily for application in satellite tuners. the device contains all elements necessary, with the exception of local oscillator sustaining network, to fabricate a high performance i(n-phase) & q(uadrature) phase splitter and downconverter optimised for systems containing rf agc gain control. the device allows for systems containing higher power analog interferers. for most applications rf tunable filtering is not essential. the SL1925 is optimised for use with a low phase noise synthesiser, a range of which are available from mitel semiconductor. this will form a complete front end tuner function for digital satellite receiver systems utilising dsp derotation recovery. the device includes a very high signal handling front end with agc, this provides for gain control, reference local oscillator with output buffer, phase splitter with i and q mixers and baseband buffer amplifiers with external interstage filtering. features single chip system for direct quadrature down conversion from l-band high signal handling capability for minimum external component count application, requires external rf agc of 30db compatible with dss and dvb system requirements excellent gain and phase match up to 30mhz baseband high output referred linearity for low distortion and multi channel application fully balanced low radiation design integral rf agc amplifier two selectable varactor tuned local oscillators with buffered output for driving external synthesiser loop esd protection (normal esd handling procedures should be observed) ordering information SL1925e/kg/np2s (tubes) SL1925e/kg/np2t (tape and reel) applications satellite receiver systems data communications systems ds4955 issue 3.0 march 2000
2 SL1925 preliminary information np28 figure 1. pin connections opfi opfq vcc psout psoutb vee tanks tanksb vee tankv tankvb vee nc vcc 128 14 15 vee ipfi vee iout losel vcc rf rfb vee agc qout vee ipfq vee figure 2. block diagram 27 agc 19 22 21 rf rfb 9 10 tankv tankvb 6 7 24 tanks tanksb losel vcos divide by 2 agc sender 0 deg 25 iout ipfi 1 opfi 14 opfq 16 ipfq 18 qout 3 psout 4 psoutb 2, 13, 23 vcc 5, 8, 11, 15, 17, 20, 26, 28 vee 90 deg vcov frequency agile phase splitter
3 preliminary information SL1925 table 1. quick reference data characteristic units operating range 950-2150 mhz input noise figure, dsb, maximum gain, 1500mhz 19 db maximum conversion gain (assuming 6db filter loss) >55 db minimum conversion gain (assuming 6db filter loss) <20 db ip3 2t input referred 113 dbuv converter input referred im3, two tones at 97db v 30 dbc ip2 2t input referred 140 dbuv p1db input referred 103 dbuv baseband amplifier output limit voltage 2.0 v gain match up to 22 mhz 0.2 db phase match up to 22 mhz 0.7 deg gain flatness up to 22 mhz 0.5 db local oscillator phase noise across entire 950mhz to 2150mhz band: ssb @ 10 khz offset 80 dbc/hz the required 950mhz to 2150mhz i and q reference lo frequencies for quadrature direct conversion are generated by the on board oscillators named ?cos?and ?cov? and the phase splitter. oscillator ?cos?operates nominally from 1900mhz to 3000mhz and is then divided by two to provide 950mhz to 1500mhz. oscillator ?cov operates nominally from 1400mhz to 2150mhz. only one oscillator is active at any time and selection is made within the phase splitter under the control of the losel input. each oscillator uses an external varactor tuned resonant network optimised for low phase noise with a single varactor line control. a recommended application circuit for the oscillators is shown in figure 4. the lo from the phase splitter drives a buffer whose outputs ?sout?and ?soutb?can be used for driving an external pll control loop for the vco?. the typical lo phase noise is shown in figure 11. the mixer outputs are coupled to baseband buffer outputs ?pfi?and ?pfq?which drive external band limit filters. the output impedance of these buffers is contained in figure 12. the outputs of the filters are then connected to the inputs ?pfi?and ?pfq?of the baseband channel amplifiers. the outputs ?out?and ?out?provide for a low impedance drive and can be used with a maximum load as in figure 3. the output impedance of this section is contained in figure 13. an example filter for application with 30ms/s systems is contained in figure 14. all port peripheral circuitry for the SL1925 is shown in figure 15a and 15b. the typical key performance data at 5v vcc and 25 c ambient are shown in the ?uick reference data of table 1. functional description the SL1925 is a wideband direct conversion quadrature downconverter optimised for application in satellite receiver systems. a block diagram is given in figure 2 and shows the device to include a broadband rf preamplifier with agc control, two oscillator sustaining amplifiers, a frequency agile 90 phase splitter, i q channel mixers and i q channel baseband amplifiers. the only additional elements required are an external tank circuit for each oscillator, and baseband interstage filters. to fabricate a complete tuner an rf agc stage offering +20db to -10 db of gain range and a 2.2 ghz pll frequency synthesiser are also required. an example application is shown in figure 16. in normal application the first satellite if frequency of typically 950 to 2150 mhz is fed via the tuner rf agc stage to the rf preamplifier, which is optimised for impedance match and signal handling. the rf preamplifier is designed such that no tracking rf filter is required and also allows for analog interferers at up to 10 db higher amplitude. the converter rf input impedance is shown in figure 5. the amplifier signal is then fed to an agc stage providing a minimum of 35db agc control, which together with the rf attenuator provides a possible overall tuner dynamic range of 65db, to allow for normal operating dynamic range and mcpc systems. the signal is then split into two balanced channels to drive the i and q mixers. the agc characteristic, and gain variation of iip3, iip2, p1db and nf are contained in figs. 6, 7, 8, 9 and 10 respectively.
4 SL1925 preliminary information figure 3. baseband output load condition 15pf 100 ? 1k ? note: stripline width =0.44mm,dimensions are approximate. marker freq (mhz) zreal ? zimag ? 1 950 90 -18 2 1350 76 -15 3 1750 63 -35 4 2150 46 -29 figure 5. converter rf input impedance (typical) 0.5 0.2 1 0 +j0.2 +j0.5 +j1 +j2 +j5 2 5 ?5 ?2 ?1 ?0.5 ?0.2 stop 2 500 start 700 x x x x x 1 2 3 4 normalised to 50 ? mhz mhz figure 4. local oscillator application circuit "vcov" 1t379 1t379 bb831 bb831 1k ? vcnt 6.15mm stripline 6.15mm stripline 9mm stripline 9mm stripline 6 7 9 10 tanks tanksb tankv tankvb "vcos" 1k ?
5 preliminary information SL1925 figure 6. converter gain variation with agc voltage (typical) -20.0 -10.0 0.0 10.0 20.0 30.0 40.0 50.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 agc control voltage (v) converter conversion gain (db) 30db minimum, agc <1v -5db maximum, agc >4v 90 95 100 105 110 115 120 -6 -1 4 9 14 19 24 29 34 converter gain setting (db) converter input referred ip3 (dbuv) figure 7. converter input referred ip3 variation with gain setting (typical)
6 SL1925 preliminary information 100 105 110 115 120 125 130 135 140 -6 -1 4 9 14 19 24 29 34 converter gain setting (db) converter input referred ip2 (dbuv) figure 8. converter input referred ip2 variation with gain setting (typical) 80 85 90 95 100 105 110 -6 -1 4 9 14 19 24 29 34 converter gain setting (db) converter rf input level at p1db (dbuv) figure 9. converter input referred 1db gain compression, p1db (typical)
7 preliminary information SL1925 10 20 30 40 50 60 20 25 30 35 40 45 50 55 system gain (db) noise figure (db) figure 10. noise figure variation with gain setting (typical)
8 SL1925 preliminary information -90 -88 -86 -84 -82 -80 -78 -76 -74 -72 -70 950 1150 1350 1550 1750 1950 2150 lo frequency (mhz) phase noise @10khz offset (dbc/hz) vcos enabled vcov enabled figure 11. lo phase noise variation with frequency (typical) figure 12. converter output impedance, opfi and opfq (typical) marker freq (mhz) zreal ? zimag ? 1 1 24 0.5 210 2511 330 3029 0.5 0.2 1 0 +j0.2 +j0.5 +j1 +j2 +j5 2 5 j5 j2 j1 j0.5 j0.2 stop 2 500 start 700 normalised to 50 ? 3 x x x 1 2 10khz 50mhz
9 preliminary information SL1925 figure 13. baseband output impedance, iout and qout (typical) marker freq (mhz) zreal ? zimag ? 1 1 11.4 3.4 2 10 9.6 0.2 3 30 7.3 4.7 figure 14. example baseband interstage filter for 30ms/s application 0.5 1 0 +j0.2 +j0.5 +j1 +j2 +j5 2 5 j5 j2 j1 j0.5 j0.2 stop 50mhz start 10khz x x x x 1 2 3 normalised to 50 ? opfi / opfq 100nf 1k ? 1k ? ipfi / ipfq 3.9pf
10 SL1925 preliminary information lo output lo outputb v cc v ref4 agc 12k control 2k v ref 3 v cc if-op-sel v ref 2 1k 1k tank tankb rf inputs opfi & opfq converter rf inputs (pins 21, 22) oscillator select input (pin 24) oscillator inputs (pins 6, 7, and 9,10) converter outputs (pins 1, 14) prescaler buffer drive (pins 3,4) agc input (pin 19) psout psoutb figure15. input/output interface circuits (sheet 1of 2) losel continued
11 preliminary information SL1925 iout and qout baseband amplifier inputs (pins 16,27) baseband outputs (pins 18, 25) figure 15 (continued). input/output interface circuits (sheet 2 of 2) ipfi and ipfq bias
12 SL1925 preliminary information table 2. electrical characteristics t amb = -20 c to + 70 c, v ee = 0v, vcc = 4.75v to 5.25v, desired channel at fc mhz.these characteristics are guaranteed by either production test or design. they apply within the specified ambient temperature and supply voltage unless otherwise stated. characteristic value min typ max units conditions pin supply current, icc 2,1 3,23 130 175 ma rf input operating frequency 21,22 950 2150 mhz system all system specification items should be read in conjunction with note 1. system noise figure, dsb 21,22 19 db maximum gain, agc = 1v variation in system nf with gain 21,22 -1 db/db see figure 10 adjust system input referred ip2 135 140 db v see note 2. system input referred ip3 110 113 db v see note 3. system conversion gain terminated voltage conversion gain into load as in figure 3. agc monotonic from vee to vcc, see figure 6 minimum agc gain 20 db agc = 4.0v, 950mhz maximum agc gain 59 db agc = 1.0v, 950mhz gain roll off 5 db 950mhz to 2150mhz system i/q gain match 18,25 -1 +1 db excluding interstage filter stage system i/q phase balance 18,25 -3 3 deg excluding interstage filter stage system i & q channel in band 18,25 1 db excluding interstage filter stage ripple lo 2nd harmonic interference level -50 dbc see note 5 lna 2nd harmonic interference -35 dbc see note 6 level all other spurii on i & q outputs 18,25 78 db v within 0 100mhz band, under all gain settings, rf input set to deliver 108db v at baseband outputs converter converter input impedance 21,22 75 ? see figure 5 converter input return loss 21,22 10 12 db converter input referred ip2 21,22 121 130 db v see note 4 converter input referred ip3 21,22 110 112 db v see note 4 converter input referred im2 21,22 -33 -24 dbc see note 4 converter input referred im3 21,22 -30 -26 dbc see note 4 converter input referred 1db 21,22 see figure 9 gain compression (p1db) converter conversion gain terminated voltage conversion gain in load as in figure 3. minimum agc gain -5 db agc = 4.0v maximum agc gain 30 db agc = 1.0v agc gain control slope variation monotonic from vee to vcc, see figure 6 agc control input current 19 -250 250 a agc bandwidth 100khz continued
13 preliminary information SL1925 table 2. electrical characteristics (continued) t amb = -20 c to + 70 c, v ee = 0v, vcc = 4.75v to 5.25v, desired channel at fc mhz. these characteristics are guaranteed by either production test or design. they apply within the specified ambient temperature and supply voltage unless otherwise stated. characteristic value min typ max units conditions pin converter output impedance 1,14 25 50 ? 0.1 to 30mhz. see figure 12 converter output limiting 1,14 0.5 1.2 vp-p no load converter bandwidth 1db 40 mhz no load converter output roll off 1,14 6 db/oct oscillator vcos operating range 6,7 1900 3000 mhz giving lo = 950mhz to1500mhz tanks/tanksb application as in figure 4. oscillator vcov operating range, 9,10 1450 2150 mhz application as in figure 4. tankv/tankvb local oscillator ssb phase noise 6,7 -80 -76 dbc/hz @ 10khz offset pll loop bw < 1khz, application as figure 4. measured at baseband outputs of 10mhz lo leakage to converter input 21,22 59 69 db v losel low voltage 24 0.6 v oscillator vcos enabled losel high voltage 24 vcc-0.7 v oscillator vcov enabled losel low current 24 -50 a losel high current 24 200 a prescaler output drive 3,4 88 db v single ended into 50 ? . synthesiser should be driven differentially prescaler output impedance 3,4 50 ? prescaler output return loss 3,4 8 db baseband amplifiers baseband amplifier input 16,27 0.1 -30mhz bandwidth impedance resistance 10 k ? capacitance 5 pf baseband amplifier input referred 16,27 94 97 db v see note 7 ip3 baseband amplifier input referred 16,27 99 111 db v see note 7 ip2 baseband amplifier input referred 16,27 -40 -34 dbc see note 7 im3 baseband amplifier input referred 16,27 -34 -22 dbc see note 7 im2 baseband amplifier input referred 16,27 84 db v terminated voltage gain into load as in 1db compression (p1db) figure 3. baseband amplifier gain 16,18 30 db terminated voltage gain into load as in 27,25 figure 3 continued
14 SL1925 preliminary information table 2. electrical characteristics (continued) t amb = -20 c to + 70 c, v ee = 0v, vcc = 4.75v to 5.25v, desired channel at fc mh z. these characteristics are guaranteed by either production test or design. they apply within the specified ambient temperature and supply voltage unless otherwise stated. characteristic value min typ max units conditions pin baseband amplifier output 18,25 20 ? impedance baseband amplifier output 18,25 2.0 vp-p pk-pk level at hard clipping. limiting load as in figure 3. baseband amplifier 1db 18,25 40 mhz load as in figure 3. bandwidth baseband output roll off 18,25 6 db/oct above 3db point, no load notes : 1. systems specifications refer to total cascaded system of front end converter/agc stage and baseband amplifier stage with nominal 6db pad as interstage filter and load impedance as in figure 3. 2. agc set to deliver output amplitude of 108db v on desired channel, input frequency fc and amplitude of 79db v, with two interferers of frequencies fc+146 and fc+155mhz at 97db v generating output intermodulation spur at 9mhz. 40mhz 3db bandwidth interstage filter included. 3. agc set to deliver output amplitude of 108db v on desired channel, input frequency fc and amplitude 79 db v, with two interferers of frequencies fc+110 and fc+211mhz at 97 db v generating output intermodulation spur at 9mhz. 40mhz 3db bandwidth interstage filter included. 4. two tones within rf operating frequency range at 97db v, conversion gain set at 4db. 5. the level of 2.01ghz downconverted to baseband relative to 1.01 ghz with the oscillator tuned to 1 ghz, measured with no input filtering. 6. the level of second harmonic of 1.01 ghz input at -25 dbm downconverted to baseband relative to 2.01 ghz at -40 dbm with the oscillator tuned to 2 ghz, measured with no input filtering. 7. two tones within operating frequency range at 77db v. characteristic value min max units conditions pin table 3. absolute maximum ratings all voltages are referred to vee at 0v (pins 5,8,11,15,17,20,26,28) supply voltage, vcc 2,13,23 -0.3 7 v transient condition only psout &psoutb dc offset 3,4 vcc-3.0 vcc+0.3 vp-p rf & rfb input voltage 21,22 2.5 vp-p ac coupled, transient conditions only all other i/o ports dc offset 1,6,7,9 -0.3 vcc+0.3 v 10,12 14,16 18,19 24,25,27 storage temperature -55 +150 c junction temperature +150 c np28 package thermal resistance chip to ambient 85 c/w chip to case 20 c/w power consumption at 5.25v 893 mw esd protection all 4 kv mil std-883 latest revision method 3015 class 1
15 preliminary information SL1925 SL1925 demo board the demo board contains an SL1925 direct conversion ic and an sp5769 synthesiser. reference to the specifications for each device may be required in conjunction with these notes. the board contains all components necessary to demonstrate operation of the SL1925. the schematic and pcb layout of the board are shown in figures 16, 17 and 18. the sp5769 synthesiser is provided to control each of the SL1925? oscillators. supplies the board must be provided with the following supplies: 5v for the synthesiser, 30v for the varactor line and 5v for the SL1925. the supply connector is a 5 pin 0.1?pitch pin header. the order of connections is 5v - gnd - 30v - gnd - 5v i 2 c bus connections the board is provided with a rj11 i 2 c bus connector which feeds directly to the sp5769 synthesiser. this connects to a standard 4 way cable which is supplied with the interface box. operating instructions 1. software use the mitel semiconductor synthesiser software. pull down the i 2 c bus section menu then select the sp5769. it is suggested that the charge pump setting 130ua is used, and the reference divider is set to 32. these settings give a small loop bandwidth (i.e. 100? hz), which allows detailed phase noise measurements of the oscillators to be taken, if desired. 2. vco control the two vco? are selected by toggling port p1 on the synthesiser which in turn toggles the losel input of the SL1925. vcos is switched on (and hence vcov off) by clicking p1 on - a tick will appear. vcos oscillates at twice the lo frequency (lower band) and is then divided by two to provide the required lo frequency in the range 950mhz to 1500mhz approximately. vcov is switched on (and hence vcos off) by clicking p1 off - no tick. vcov oscillates at the lo frequency (upper band) in the range 1450mhz to 2150mhz approximatley. 3. agc control the agc input of the SL1925 which determines the conversion gain should be controlled by application of an external voltage to the agc pin, tp1. caution: care should be taken to ensure the chip is powered on when +ve voltages are applied to the agc input so as to avoid powering the chip up via the esd protection diode of the agc input. it is recommended that a low current limit is set on the external source used. 4. free running the vco s select the required vco using port p1 and then using the software choose an lo frequency which is above the maximum frequency capability of the oscillator. 3ghz is suggested for both oscillators. under this condition the varactor control voltage is pumped to its maximum value, i.e. to the top of the band. the oscillator frequency may be manually tuned by varying the 30v supply.
16 SL1925 preliminary information figure 16. SL1925 l band quadrature downconverter title: mitel op fi 1 vcc 2 psout 3 psoutb 4 vee 5 tanks 6 tanksb 7 vee 8 tankv 9 tankvb 10 vee 11 nc 12 vcc 13 op fq 14 vee 15 ip fq 16 vee 17 q out 18 agc 19 vee 20 rf inb 21 rf ina 22 vcc 23 lo sel 24 i out 25 vee 26 ip fi 27 vee 28 ic1 SL1925 c26 100nf r4 1k r3 1k c25 100nf 5v 5v 5v c14 1nf c13 1nf l1 l2 l3 l4 vd1 1t379 vd2 1t379 vd3 bb811 vd4 bb811 c23 100nf r1 1k r2 1k c24 100nf c6 220nf c5 220nf c16 1nf c2 1nf c1 1nf r102 120r port p1 8 port p0 9 address 10 ref/comp 11 rf ip 13 vee 15 rf ip 14 ch pump 1 xtal cap 2 xtal 3 sda 4 scl 5 p3/ll 6 p2 7 vcc 12 drive 16 ic2 sp5769 c60 150pf c30 82pf x1 4mhz r16 10k t1 bcw31 c31 15nf c32 68pf r7 13k 5v synth r8 22k r10 1k r19 1k r9 15k c39 2n2 c4 3p9 c3 3p9 c50 100nf c51 100pf c42 100pf c44 100pf + c41 4u7 c47 100pf c43 100nf c49 100nf c33 100nf r5 100r sma3 i out c80 15pf r18 1k r100 0r 1 2 3 j4 sma5 ip/op fi tp1 ext agc volts sma1 rf in r6 100r sma2 q out c81 15pf r17 1k r101 0r 1 2 3 j2 sma6 ip/op fq sda5 3 5v0 4 gnd 5 scl5 6 j3 i2c bus c37 100pf c38 100pf 5v + c52 4u7 1 2 3 4 5 j1 dc power 30v 5v synth c34 100nf lo select lo select pscb pscb psca psca +5v +5v +30v gnd gnd link information 2-3 filter input 1-2 filter output link information 2-3 filter input 1-2 filter output stripline dimensions l1 & l2 6.0mm x 0.44mm l3 & l4 8.0mm x 0.44mm approximate l1 & l2 6.15mm x 0.44mm l3 l4 9.0mm x 0.44mm bb831 bb831
17 preliminary information SL1925 figure 17. top view
18 SL1925 preliminary information figure 18. bottom view

m mitel (design) and st-bus are registered trademarks of mitel corporation mitel semiconductor is an iso 9001 registered company copyright 1999 mitel corporation all rights reserved printed in canada technical documen t a tion - n o t for resale world headquarters - canada tel: +1 (613) 592 2122 fax: +1 (613) 592 6909 north america asia/paci?c europe, middle east, tel: +1 (770) 486 0194 tel: +65 333 6193 and africa (emea) fax: +1 (770) 631 8213 fax: +65 333 6192 tel: +44 (0) 1793 518528 fax: +44 (0) 1793 518581 http://www.mitelsemi.com information relating to products and services furnished herein by mitel corporation or its subsidiaries (collectively mitel) is believed to be reliable. however, mitel assumes no liability for errors that may appear in this publication, or for liability otherwise arising from the application or use of any such information, product or service or for any infringement of patents or other intellectual property rights owned by third parties which may result from such application or use. neither the supply of such information or purchase of product or service conveys any license, either express or implied, under patents or other intellectual property rights owned by mitel or licensed from third parties by mitel, whatsoever. purchasers of products are also hereby noti?ed that the use of product in certain ways or in combination with mitel, or non-mitel furnished goods or services may infringe patents or other intellectual property rights owned by mitel. this publication is issued to provide information only and (unless agreed by mitel in writing) may not be used, applied or reproduced for any purpose nor form part of any order or contract nor to be regarded as a representation relating to the products or services concerned. the products, their speci?cations, services and other information appearing in this publication are subject to change by mitel without notice. no warranty or guarantee express or implied is made regarding the capability, performance or suitability of any product or service. information concerning possible methods of use is provided as a guide only and does not constitute any guarantee that such methods of use will be satisfactory in a speci?c piece of equipment. it is the users responsibility to fully determine the performance and suitability of any equipment using such information and to ensure that any publication or data used is up to date and has not been superseded. manufacturing does not necessarily include testing of all functions or parameters. these products are not suitable for use in any medical products whose failure to perform may result in signi?cant injury or death to the user. all products and materials are sold and services provided subject to mitels conditions of sale which are available on request.

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