Research And Design Of5-GHz Voltage-Controlled Oscillator And Prescaler

With the rapid development of wireless communication technology and CMOStechnology, research of fully integrated radio frequency (RF) transceivers has beenhighly promoted. Among advances in these researches, high-performance frequencysynthesizer is the key to the overall performance of integrated RF transceivers.In this thesis, the architecture and linear model of charge pump phase-locked loopare introduced. Meanwhile, the principles of operation, basic circuit configuration andperformance parameters of voltage-controlled oscillator in the phase-locked loop arealso researched. Simultaneously, the phase noise of the oscillator is analyzed accordingto the mathematical model of the phase noise, and the advantages and disadvantages ofdual-modulus prescaler are compared between traditional dual-modulus prescaler andthe phase switching technique-based prescaler.According to the requirements of2.4GHz wireless transceiver for Zigbeeapplications, a LC voltage controlled oscillator and a fractional dual-modules presaclerare designed using TSMC0.18μm RFCMOS technology. Voltage controlled oscillatoradopts differential complementary cross-coupled pairs and binary varactors arraies, toachieve multi-channel frequency tuning, as well as to improve output swings and tooptimize phase noise. Moreover, automatic-amplitude control circuit is used to stabilizethe output amplitude. The dual-modulus prescaler adopts phase-switching architecture,and the divide-by-2dividers adopt current model logic architecture to improve thecircuit operating speed and lower power consumption. The circuit is simulated bySpectreRF, and the results shows that frequency of LC voltage-controlled oscillator is4654-5172MHz, center frequency of which is approximately4.87GHz; the tuning rangeis up to37.2%; the power consumption of core oscillator is about0.74-2.75mW; thephase noise of center frequency is-91.34dBc/Hz@100KHz. The division ratio ofdual-modulus prescaler is32/32.5, with highest operating frequency up to7GHz,consuming a2.83mW-power, and the rising/falling delay of output signal is91.6ps and95.9ps, respectively. The simulation results show that the design meets the specificationof the system.