LINEAR AMPLIFIER USING NON-LINEAR CMOS CAPACITORS

The invention provides an amplifier circuit made by digital CMOS processes, the amplifier circuit comprising a main operational amplifier with at least one input and at least one output and a feedback loop including a non-linear gateoxide capacitor, wherein a voltage control means is connected to the main operational amplifier to provide a voltage difference between the output common mode voltage and the input common mode voltage of the main operational amplifier to apply a DC biasing voltage across the non-linear gateoxide capacitor sufficient to operate the non-linear gateoxide capacitor in a bias range where the capacity of the none-linear gateoxide capacitor is almost independent of the applied voltage comprising the bias voltage plus a signal voltage.