High-speed communication circuits: Voltage control oscillators and VCO-derived filters
Chen, Huiting (2004) High-speed communication circuits: Voltage control oscillators and VCO-derived filters. PhD thesis, Iowa State University.
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Voltage Controlled Oscillators (VCO) and filters are the two main topics of focus in this dissertation. A temperature and process compensated VCO, which is designed to operate at 2 GHz, and whose frequency variation due to incoming data is limited to 1% of its center frequency was presented. The test results show that, without process changes present, the frequency variation due to a temperature change over 0°C to 100 °C is around 1.1% of its center frequency. This is a reduction of a factor of 10 when compared to the temperature variation of a conventional VCO. A new method of designing continuous-time monolithic filters derived from well-known voltage controlled oscillators (VCOs) was introduced. These VCO-derived filters are capable of operating at very high frequencies in standard CMOS processes. Prototype low-pass and band-pass filters designed in a TSMC 0.25 mm process are discussed. Simulation results for the low-pass filter designed for a cutoff frequency of 4.3 GHz show a THD of –40 dB for a 200 mV peak-peak sinusoidal input. The band-pass filter has a resonant frequency programmable from 2.3 GHz to 3.1 GHz, a programmable Q from 3 to 85, and mid-band THD of –40 dB for an 80 mV peak-peak sinusoidal input signal. A third contribution in this dissertation was the design of a new current mirror with accurate mirror gain for low b bipolar transistors. High mirror gain accuracy is achieved by using a split-collector transistor to compensate for base currents of the source-coupled.
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