Hong Kong Applied Science and Technology Research Institute Company, Limited

Zhongliang Zhou

Huimin Guo

Yat Tung Lai

An RC oscillator has a variable capacitor that sets the output frequency. The variable capacitor has m binary-weighted switched capacitor arrays, and each binary-weighted switched capacitor array has binary-weighted capacitors. p binary bits are decoded into an m-bit thermometer code that selects one of the m binary-weighted switched capacitor arrays to use n binary bits to switch its binary-weighted capacitors. Other binary-weighted switched capacitor arrays have all their capacitors switched on, or all their capacitors switched off by the thermometer code. The smallest or unit capacitance of each binary-weighted switched capacitor array is adjusted to compensate for the non-linear reciprocal relationship of frequency being proportional to 1/RC. The unit capacitance is increased for each successive binary-weighted switched capacitor array to reset to the ideal linear relationship of the (p,n)-bit code to frequency.

RC oscillator that uses thermometer codes to select a sub-array and binary codes to select capacitors or resistors within a sub-array for linear and monotonic tuning

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Hong Kong, China

Zhongliang Zhou