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MICRF102 Wireless Transmitter Circuit

2016-04-07 12:12  
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Wireless transmitter circuit as shown, the circuit MICRF102 as the core.MICRF102Micrel Inc. launched a single-chip UHF ASK transmitter, SOP (M) -8 package, chip: by the reference oscillator, phase detector, divider, band-pass filter, VCO composed of synthetic, transmit bias control circuit RF power amplifiers, antenna tuning control, and varactor diodes, etc., is a real "data entry - wireless output" single-chip wireless transmitter devices. UHF synthesizer generates the carrier frequency and quadrature signal output. The input phase signal (I) used to drive the RF power amplifier. Antenna tuned quadrature signal (Q) used to compare the antenna signal phase. The antenna tuning control part of the detection antenna channel launch phase of the signal and control the capacitance of the varactor tuned antenna, antenna tuning. The power amplifier output by the control unit controls the emission bias. ASK / OOK modulation, low-power mode, the data transfer rate of 20 kb / s.
MICRF102 Wireless Transmitter Circuit
Use should be noted that the problem is: (1) REFOSC (pin 4) is the reference oscillation side, connect the crystal to the ground or using the AC coupling mode input peak - to 0.5-V clock pulse. The emission frequency is 32 times the reference oscillator frequency: × 32 = emission frequency of the reference oscillation frequency. If you use an external clock signal should be AC-coupled input signal amplitude peak - 200 ~ 500 mV. (2) MICRF102 using the differential output to drive the antenna load. The power amplifier output stage includes a varactor diode, it automatically inductor tuner and antenna to resonance on the emission frequency. Typical PCB wire antennas the size of the inductor and the loop antenna conductor width, the thickness of the PCB copper foil and the location of the ground plane. Varactor capacitance value of 6.5 pF, the general choice of the design. Antenna inductance L by the formula L = 1 / (4π2f2C) calculation. (3) the voltage on the power amplifier output power and the PC side (pin 1). Normal operation, the voltage on the side of the pin is set between 0.2 ~ 0.4 V- Voltage rise on the PC side, increase the output power; However, if the voltage exceeds 0.4 V on the PC side, the power amplifier is current limiting output power no longer increased. To reduce the voltage of the PC side can reduce electrical power consumption, but also reduce the RF output power. (4) the STBY (pin 5) is in standby mode control. Tied to VDD for the launch, connected to VSS in standby mode. (5) MICRF102 chip is sensitive to the power supply ripple properly supply bypassing is required, the general use of 4.7μF, 0.1μF, 100 pF capacitor in parallel between the VDD and VSS.