The Key Technology And Application Research Of C-band And K-band Transceiver Front-end

The wireless communication, radio frequency identification devices and civil radar of C-band and K-band are widely used. With the consideration of practical project, based on the main principle and key techniques of transceiver front-end, the 5.8GHz frequency synthesizer, 2ASK modulator, C-band transceiver chain,24GHz sweep source and transmitter chain, receiver chain of high sensitivity are properly designed, and the function of K-band FMCW radar ranging is verified. The main contents of this thesis include two part as follows:1. Research on the main module of C-band transceiver front-end:(1) C-band frequency synthesizer:Based on the scheme of integer-N phase-locked loop, the C-band frequency synthesizer is designed. With the application of a suitable ultra-wideband phase-locked loop chip MAX2870, which integrated with voltage control oscillators and phase frequency detectors, the module is realized. The reference signal is generated by a temperature-compensation crystal oscillator. The signal of 5.8GHz and 5.84GHz can be generated by setting the fractional dividers via the chip control program. The output power is 1.2dBm at 5.8GHz, the spurious suppression is more than 58dBc, the phase noise is -98.07dBc/Hz@100KHz; The output power at 5.84GHz is around 0.8dBm, the phase noise is -99.31dBc/Hz@100KHz.(2) C-band transmitter:The transmitter chain is integrated with 2ASK modulator, which is suitable for the ETC transmitter front-end. The modulation depth is the main requirements of 2ASK modulator, With the application of two cascaded Voltage-controlled anttenuators HMC9731p3, the modulation depth is improved. The operating frequency of this modulator covers 0.5-6GHz, and the modulation depth range of this modulator is 0-50 dB. The last power amplifier is SE5017L from Skyworks, the largest transmitting power can be 27dBm.(3) C-band receiver:The receiver is a superheterodyne receiver, two stages of LNAs are adopted to reduce the noise figure and improve the overall gain, the largest gain of receiver chain can be 65dB, and the sensitivity can be-85dBm. The second stage of LNA can be bypassed through the power detector of AGC chip, the automatic gain control of RF circuit is realized. The IF AGC is achieved by cascading two stages of AGC chip, the dynamic range can be 50dB. The output power of receiver is -1dBm±10dB when the input power changed from -80dBm to OdBm. The filter capacitor of AGC feedback circuits can be adjusted to solve the problem of counter-modulation.2. Research on the main module of K-band transceiver front-end:(1) K-band frequency synthesizer:Based on the fractional-N phase-locked loop, the K-band LFMCW frequency synthesizer is designed. This module is realized by the suitable transceiver chip BGT24MTR11 which integrated low phase noise VCO and the high performance fractional synthesizer chip HMC703, the reference signal is generated by the external crystal, the FMCW signal of 24?24.125GHz can be generated by enabling thefunction of frequency ramp..The phase noise at 24GHz is -81.1dBc/Hz@100KHz; The phase noise at 24.125GHz is -81.9050dBc/Hz@100KHz; and the swept-frequency of 24-24.125GHz is achieved.(2) K-band transmitter:the transimitter chain included power amplifier in the transceiver chip and the K-band balun. The matching circuit is designed to improve the output VSWR of the power amplifier, and the K-band 180° balun is designed based on the structure of coupler. The frequency of RF signal is 24?24.125GHz and the average output power of transimitter is about 0.2 dBm.(3) K-band receiver:the K-band receiver chain is designed based on the Zero-IF technology, with the application of external LNA module, orthogonal mixer of the transceiver chip and the IF differential amplifier, the down-conversion and amplification of RF signal is achieved. The IF frequency covers DC-lOMHz, the noise figure is around 5.54dB, the gain is about 33.281dB.(4) K-band FMCW radar ranging:When combined with the horn antenna, the K-band FMCW frequency synthesizer and transceiver chain can realize the basic ranging function of FMCW radar. All the measured performance parameters of the designed receiver and FMCW radar can meet the pre-specified requirements.