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| Preliminary 5 Typical Applications * Digital and Spread-Spectrum Systems * GMSK, QPSK, DQPSK, QAM Modulation * Private Mobile Radio and TETRA systems * AM, SSB, DSB Modulation * Image-Reject Upconverters RF2485 VHF QUADRATURE MODULATOR Product Description The RF2485 is a monolithic integrated universal modulation system capable of generating modulated AM, PM, or compound carriers in the VHF and UHF frequency range. The IC contains all of the required components to implement the modulation function including differential amplifiers for the baseband inputs, a 90 hybrid phase splitter, limiting LO amplifiers, two balanced mixers, a combining amplifier, and an output RF amplifier which will drive a 50 load. Component matching, which can only be accomplished with monolithic construction, is used to full advantage to obtain excellent amplitude balance and high phase accuracy. The unit features low power consumption, single power supply operation and adjustment free operation with no external parts required to operate the part as specified. Optimum Technology Matching(R) Applied Si BJT Si Bi-CMOS GaAs HBT SiGe HBT 0.156 0.148 .018 .014 0.010 0.004 5 MODULATORS AND UPCONVERTERS 0.347 0.339 0.050 0.252 0.236 0.059 0.057 8 MAX 0 MIN 0.0500 0.0164 0.010 0.007 u Package Style: SOIC-14 GaAs MESFET Si CMOS Features * Single 5V Power Supply * Low Power * Excellent Amplitude and Phase Balance * Extremely Low Broadband Noise Floor * 200MHz to 600MHz Operation VDD2 1 VDD1 2 NC 3 I SIG 4 I REF 5 Q REF 6 Q SIG 7 POWER CONTROL 14 RF OUT 13 GND2 12 GND 11 GND 10 GND1 +45 -45 9 PHASE 8 LO IN Ordering Information RF2485 RF2485 PCBA VHF Quadrature Modulator Fully Assembled Evaluation Board Functional Block Diagram RF Micro Devices, Inc. 7625 Thorndike Road Greensboro, NC 27409, USA Tel (336) 664 1233 Fax (336) 664 0454 http://www.rfmd.com Rev A3 010820 5-55 RF2485 Absolute Maximum Ratings Parameter Supply Voltage Input LO and RF Levels Operating Ambient Temperature Storage Temperature Preliminary Rating -0.5 to +7.5 +10 -40 to +85 -40 to +150 Unit VDC dBm C C Caution! ESD sensitive device. RF Micro Devices believes the furnished information is correct and accurate at the time of this printing. However, RF Micro Devices reserves the right to make changes to its products without notice. RF Micro Devices does not assume responsibility for the use of the described product(s). Parameter LO Input Frequency Range Power Level Input VSWR Specification Min. Typ. Max. 200 -3 1.2:1 600 +6 Unit MHz dBm Condition T=25C, VDD =5VDC, I&Q inputs=2VPP 5 MODULATORS AND UPCONVERTERS With external 50 termination; see application schematic, note A. 100 3.0 MHz V V V V mV dB Modulation Input Frequency Range Reference Voltage (VREF) Modulation (I&Q) Modulation (I&Q) Maximum Modulation (I&Q) Input Resistance DC Offset Amplitude Error (I/Q) Quadrature Phase Error DC 2.0 VREF 0.7 VREF 1.5 VREF 2.5 3000 50 0.2 1 I & Q signals for -0.5dBm output power. I & Q signals for +5dBm output power. In-phase and quadrature signals. ISIG -IREF and QSIG -QREF; to achieve maximum carrier suppression. From 350MHz to 450MHz. VDD =5V, LO Power=0dBm, LO Freq=400MHz, SSB, I&Q input=0.7VP 150 3 RF Output Output Power Output Impedance Output VSWR Broadband Noise Floor Sideband Suppression Carrier Suppression -1.5 -0.5 50 1.5:1 -149 43 26 dBm -147 dBm/Hz dB dB 30 20 At 5MHz offset Unadjusted Modulation DC offset can be externally adjusted for optimum suppression. Suppression is typically better than 25dB without adjustment. IM3 -40 -3.0 -52 -2.5 -2.0 dBc dBm dBc 1.7VP-P TETRA Modulation LO, 450MHz@ -5.0dBm, VREF 2.5V VCC=5.0V TETRA Modulation Channel Power Adjacent Channel Power Rejection 25kHz 50kHz -47.0 -67.0 -48.0 -68.5 5 4.5 Current 28 5.5 39 -49.0 -70.0 dBc dBc V V mA Specifications Operating Limits Operating Power Supply Voltage 5-56 Rev A3 010820 Preliminary Pin 1 Function VDD2 Description Power supply for the RF Output amplifier. An external RF bypass capacitor is needed. The trace length between the pin and the bypass capacitor should be minimized. The ground side of the capacitor should connect immediately to the ground plane. Power supply for all other circuits. An external RF bypass capacitor is needed. No connection. Baseband input to the I mixer. This pin is DC coupled. Maximum output power is obtained when the input signal has a peak to peak amplitude of 5V. The DC level supplied to this pin should be 2.50.5V. The SIG and REF inputs are inputs of a differential amplifier. Therefore the REF and SIG inputs are interchangeable. If swapping the I SIG and I REF pins, the Q SIG and Q REF also need to be swapped to maintain the correct phase. It is also possible to drive the SIG and REF inputs in a balanced mode. This will increase the gain. RF2485 Interface Schematic 2 3 4 VDD1 NC I SIG I REF I SIG 5 5 I REF Reference voltage for the I mixer. This voltage should be the same as See pin 4. the DC voltage supplied to the I SIG pin. To obtain a carrier suppression of better than 40dB it may be tuned 0.15V (relative to the I SIG DC voltage). Without tuning, it will typically be better than 25dB. Reference voltage for the Q mixer. This voltage should be the same as Same as pin 3. the DC voltage supplied to the Q SIG pin. To obtain a carrier suppression of better than 40dB it may be tuned 0.15V (relative to the Q SIG DC voltage). Without tuning, it will typically be better than 25dB. The SIG and REF inputs are inputs of a differential amplifier. Therefore the REF and SIG inputs are interchangeable. If swapping the I SIG and I REF pins, Q SIG and Q REF also need to be swapped to maintain correct phase. It is also possible to drive the SIG and REF inputs in a balanced mode. This will increase the gain. Baseband input to the Q mixer. This pin is DC coupled. Maximum out- Same as pin 4. put power is obtained when the input signal has a peak to peak amplitude of 5V. The DC level supplied to this pin should be 2.50.5V. The input of the phase shifting network. This high impedance input can LO IN be matched with an external 56 termination resistor. This pin is internally connected to ground through a 4k resistor. Putting a DC voltage on this pin is not recommended. However, connecting this pin to ground, e.g., through a shunt inductor, is allowed. MODULATORS AND UPCONVERTERS PHASE 6 Q REF 7 8 Q SIG LO IN 9 PHASE 10 11 12 13 GND1 GND GND GND2 This pin allows to adjust the phase of the I/Q signals. However, the control is very sensitive and hard to control. Control voltage change for a few degrees adjustment is in the order of 10mV. Device to device and temperature variation are not characterized. Therefore it is not recommended to use this pin; leave it not connected. Do NOT connect to ground.For compensating large errors in the I/Q signals supplied to the device or in control loops this pin may prove useful. Ground connection of the LO phase shift network. This pin should be connected directly to the ground plane. Ground connection for other circuits. Keep traces short and connect to ground plane immediately. Same as pin 11. Ground connection for the RF output stage. A good ground connection is especially important at this pin to avoid interference with other circuits. Rev A3 010820 5-57 RF2485 Pin 14 Function RF OUT Description 50 output. This pin carries a DC voltage, and an external blocking capacitor is recommended. Preliminary Interface Schematic RF OUT 5 MODULATORS AND UPCONVERTERS 5-58 Rev A3 010820 Preliminary Application Schematic VDD 1 100 nF 2 100 pF I INPUT ZIN=100 Coupling Capacitor 100 VREF 100 100 NC 3 4 5 6 7 +45 -45 RF2485 100 pF 14 POWER CONTROL 13 12 11 10 9 100 pF 8 56 Note A 50 strip RF OUTPUT 100 Q INPUT ZIN=100 50 strip LO INPUT 5 MODULATORS AND UPCONVERTERS Coupling Capacitor NOTE A: Optional; input impedance is about 79-J158 at 400 MHz without resistor. SMD resistor mounted adjacent to package pin, grounded through a via to the ground plane. Rev A3 010820 5-59 RF2485 Evaluation Board Schematic (Download Bill of Materials from www.rfmd.com.) P1 P1-1 1 2 P1-3 3 CON3 C3 100 pF P1-1 C2 100 nF C1 33 pF 1 2 3 4 P1-3 C5 33 pF 50 strip 5 6 7 POWER CONTROL 14 13 12 11 10 +45 -45 Preliminary VDD GND VREF 50 strip J4 RF OUT 5 MODULATORS AND UPCONVERTERS J1 I SIG 50 strip 9 8 C4 100 pF 50 strip R1 56 J2 Q SIG J3 LO IN 2485400, Rev. - 5-60 Rev A3 010820 Preliminary Evaluation Board Layout Board Size 2.0" x 2.0" Board Thickness 0.031", Board Material FR-4 RF2485 5 MODULATORS AND UPCONVERTERS Rev A3 010820 5-61 RF2485 Preliminary 5 MODULATORS AND UPCONVERTERS 5-62 Rev A3 010820 |
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