應用於無線區域網路802.11b/g與60GHz之壓控振盪器電路設計

Abstract

In this thesis, design of the voltage controlled oscillator (VCO) in radio frequency system is presented. The circuits discussed in this thesis are design to operate at different frequencies and they are implemented by using different process technologies. For individual circuit, we describe its structure and principles, and finally discuss the results of simulation and measurement. In Chapter two, a Colpitts differential VCO circuit is designed, in which, the gm-boosting transistors are used to increase the value of its transconductance and to reduce the required start-up current. The feedback capacitor divider can also increase the output amplitude and improve the performance. The measured oscillation frequencies are from 2.66GHz to 2.72GHz, and the measured phase noise is -113dBc/Hz @ 1MHz frequency offset. In Chapter three, we present a complementary low power VCO circuit design. The complementary structure can increase the value of transconductance, thus it can increase transistor switching speed and reduce the power consumption. Furthermore, the second harmonic of the tail current source is filtered out by using the noise filter technique. The measured oscillation frequencies are from 2.12GHz to 2.74GHz, and the measured phase noise is -102dBc/Hz @ 1MHz frequency offset. The measured power consumption is 11.84mW. The content of Chapter four is a 60GHz VCO which is mainly designed by using microstrip lines. The use of addition cross couple pair and transmission lines increase the transconductance, and the microstrip lines need to be selected as appropriate length to achieve the best performance. In addition, we also used the source degenerated capacitance technique to increase the oscillation frequency and the tuning range. The simulated center oscillation frequency is 61.23GHz, and the phase noise is -96dBc/Hz @ 1MHz frequency offset. The tuning range is 59.9GHz-62.36GHz.