A 1.2-V CMOS $RC$ Oscillator for Capacitive and Resistive Sensor Applications

An accurate self-adjusting CMOS RC oscillator for capacitive and resistive sensor applications has been designed and manufactured. The oscillator operates with supply voltages from 1.2 to 3 V and achieves an internal accuracy of plusmn0.7% with a temperature range from -20degC to 60degC. The RC oscillator was fabricated in a 0.35-mum standard n-well CMOS process with threshold voltages of 0.5 and -0.65 V. Its design and operation are described, and results of measurements performed on the fabricated chips are presented.