5GHz Automatic Amplitude Calibration VCO Using Synchronous Clock Temperature Compensation

A novel LC-tank voltage-controlled oscillator (VCO) is presented to compensate for the output amplitude drift caused by temperature variations while maintaining a low phase noise and an operating frequency range. A prototype VCO using a TSMC 180nm CMOS technology has been designed at a 1.8V supply voltage and consumed 3.4mA current. The temperature compensation circuit incorporates a clock counter, a peak detector, a comparator, and a finite state machine, which controllers the 3-bit binary tail current to reduce the amplitude shift when temperature varies between -40<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sup>C and 100<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sup>C. The simulated results show that the proposed VCO can automatically calibrate output amplitude in real-time. The proposed VCO has an operating frequency ranging from 4.1 to 5.7GHz, and the minimum phase noise at 1MHz offset frequency is -118dBc/Hz.