Study CMOS VCO

Voltage controlled oscillator (VOC), as the key component of the signal source, iswidely used in electronic systems. Frequency source, which is the core of the wirelesscommunication system, is an important part of most electronic systems. CMOS processis widely used in communication system chip because it possess a wide range of voltageregulation, low power consumption, strong anti-interference ability, etc. Relative to LCoscillator, circular voltage-controlled oscillator has a lot of advantages such as wideadjustment range, low power consumption, small size, high integration and is widelyused in the field of communications.This paper, using Cadence Caliber software for simulation analysis, designed afourth order of circular voltage-controlled oscillator which is based on TSMC0.18umprocess. It includes three modules, the bias circuit, voltage controlled oscillator andbuffer. The bias circuit provides differential ring oscillator with a current source unitcircuit, which gives the output of the voltage-controlled oscillator better linearity andstability. Adopting a fourth-order differential ring oscillator can keep a stableequilibrium state when levels even oscillator and odd number difference structurevibrate, and may also lock the circuit before vibrate and keep the circuit in a stableequilibrium. Buffer circuit can be extended to the bandwidth of the system, which theoutput power tube charges and discharges under the dynamic condition, thus theresponse speed of the circuit can be improved and the static power of the circuit can bereduced. From the perspective of simulation structure, the adjusting frequency range ofthe designed oscillator is between2.34GHz to2.34GHz and center frequency phase1MHz noise is-123dBc/Hz, power consumption is2.07mW and wave is gentle as toachieve the requirements of the oscillation amplitude of relative. Finally, using landscape design tools Virtuoso Layout Editor to design a voltage-controlled oscillatorlandscape. The landscape area is71.8179.01μm2, and a simulation was carried out.