Abstract:
An amplifier and corresponding method include a field-effect transistor (FET) amplifier and a cascode FET. Each FET may operate with a positive ratio between its third-order nonlinearity coefficient and its linear gain. An inductor added at a gate of the cascode FET, operatively coupled with other components in a circuit, results in a first equivalent impedance looking into an input of the cascode FET. The first equivalent impedance may substantially offset a distortion output of the FET amplifier based upon the added inductor. The inductor operatively coupled with the circuit may result in a second equivalent impedance looking out of the gate of the cascode FET. The second equivalent impedance may substantially offset a distortion output of the cascode FET based upon the added inductor. In addition, a programmable capacitor connected between the gate and drain of the cascode FET may further substantially offset a distortion output of each FET.
Abstract:
An instrumentation amplifier that includes input capacitance cancellation is provided. The architecture includes programmable capacitors between the input stage and a current feedback loop of the instrumentation amplifier to cancel input capacitances from electrode cables and a printed circuit board at the front end. An on-chip calibration unit can be employed to calibrate the programmable capacitors and improve the input impedance.