RF2485 Preliminary 5 VHF QUADRATURE MODULATOR Typical Applications • Digital and Spread-Spectrum Systems • AM, SSB, DSB Modulation • GMSK, QPSK, DQPSK, QAM Modulation • Image-Reject Upconverters • Private Mobile Radio and TETRA systems Product Description 0.156 0.148 GaAs HBT Si Bi-CMOS SiGe HBT ü 0.010 0.004 5 0.347 0.339 0.050 0.252 0.236 0.059 0.057 8° MAX 0° MIN 0.0500 0.0164 Optimum Technology Matching® Applied Si BJT .018 .014 MODULATORS AND UPCONVERTERS 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 50Ω 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. 0.010 0.007 Package Style: SOIC-14 GaAs MESFET Si CMOS Features • Single 5V Power Supply VDD2 1 VDD1 2 POWER CONTROL 14 RF OUT • Low Power 13 GND2 • Excellent Amplitude and Phase Balance NC 3 12 GND I SIG 4 11 GND • Extremely Low Broadband Noise Floor • 200MHz to 600MHz Operation I REF 5 Σ 10 GND1 +45° -45° Q REF 6 9 PHASE Q SIG 7 8 LO IN Functional Block Diagram Rev A3 010820 Ordering Information RF2485 RF2485 PCBA VHF Quadrature Modulator Fully Assembled Evaluation Board RF Micro Devices, Inc. 7625 Thorndike Road Greensboro, NC 27409, USA Tel (336) 664 1233 Fax (336) 664 0454 http://www.rfmd.com 5-55 RF2485 Preliminary Absolute Maximum Ratings Parameter Supply Voltage Input LO and RF Levels Operating Ambient Temperature Storage Temperature Rating Unit -0.5 to +7.5 +10 -40 to +85 -40 to +150 VDC dBm °C °C Specification Min. Typ. Max. Parameter 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). Unit T=25°C, VDD =5VDC, I&Q inputs=2VPP LO Input MODULATORS AND UPCONVERTERS 5 Condition Frequency Range Power Level Input VSWR 200 -3 600 +6 MHz dBm 1.2:1 With external 50Ω termination; see application schematic, note A. Modulation Input Frequency Range Reference Voltage (VREF) Modulation (I&Q) Modulation (I&Q) Maximum Modulation (I&Q) Input Resistance DC Offset DC 2.0 Amplitude Error (I/Q) Quadrature Phase Error 100 3.0 VREF ±0.7 VREF ±1.5 VREF ±2.5 3000 50 150 MHz V V V V Ω mV 0.2 ±1 ±3 dB ° RF Output Output Power Output Impedance Output VSWR Broadband Noise Floor Sideband Suppression Carrier Suppression -1.5 30 20 -0.5 50 1.5:1 -149 43 26 IM3 -40 -52 -3.0 -2.5 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 dBm Ω -147 dBm/Hz dB dB At 5MHz offset Unadjusted Modulation DC offset can be externally adjusted for optimum suppression. Suppression is typically better than 25dB without adjustment. dBc TETRA Modulation Channel Power -2.0 Adjacent Channel Power Rejection dBm dBc 25kHz 50kHz -47.0 -67.0 -48.0 -68.5 -49.0 -70.0 dBc dBc 5.5 39 V V mA 1.7VP-P TETRA Modulation LO, 450MHz@ -5.0dBm, VREF 2.5V VCC=5.0V Power Supply Voltage 5 4.5 Current 5-56 28 Specifications Operating Limits Operating Rev A3 010820 RF2485 Preliminary Pin 1 Function VDD2 2 VDD1 3 4 NC I SIG Description Interface Schematic 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 2.5±0.5V. 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. I REF I SIG 5 I REF 6 Q REF 7 Q SIG 8 LO IN 9 PHASE 10 GND1 11 GND 12 13 GND GND2 Rev A3 010820 MODULATORS AND UPCONVERTERS 5 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 2.5±0.5V. The input of the phase shifting network. This high impedance input can LO IN be matched with an external 56Ω termination resistor. This pin is internally connected to ground through a 4kΩ 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. 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. PHASE Ground connection for the RF output stage. A good ground connection is especially important at this pin to avoid interference with other circuits. 5-57 RF2485 Pin 14 Function RF OUT Preliminary Description Interface Schematic 50Ω output. This pin carries a DC voltage, and an external blocking capacitor is recommended. RF OUT MODULATORS AND UPCONVERTERS 5 5-58 Rev A3 010820 RF2485 Preliminary Application Schematic VDD 100 pF 1 2 100 pF Coupling Capacitor I INPUT ZIN=100 100 Ω VREF 100 Ω 100 Ω Q INPUT ZIN=100 100 Ω RF OUTPUT POWER CONTROL 13 NC 3 12 4 11 5 10 Σ +45° -45° 6 9 7 8 100 pF Coupling Capacitor 5 50 Ω µstrip LO INPUT MODULATORS AND UPCONVERTERS 100 nF 50 Ω µstrip 14 56 Ω Note A NOTE A: Optional; input impedance is about 79-J158 Ω 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 Preliminary Evaluation Board Schematic (Download Bill of Materials from www.rfmd.com.) P1 P1-1 P1-3 1 VDD 2 GND 3 VREF CON3 C3 100 pF P1-1 C2 100 nF 5 MODULATORS AND UPCONVERTERS J1 I SIG C1 33 pF 50 Ω µstrip P1-3 50 Ω µstrip POWER CONTROL 12 4 11 Σ 10 +45° -45° 6 9 7 8 C4 100 pF 2485400, Rev. - 5-60 J4 RF OUT 13 3 5 C5 33 pF J2 Q SIG 2 50 Ω µstrip 14 1 50 Ω µstrip J3 LO IN R1 56 Ω Rev A3 010820 RF2485 Preliminary Evaluation Board Layout Board Size 2.0” x 2.0” Board Thickness 0.031”, Board Material FR-4 MODULATORS AND UPCONVERTERS 5 Rev A3 010820 5-61 RF2485 Preliminary MODULATORS AND UPCONVERTERS 5 5-62 Rev A3 010820