Amplifying circuit with offset compensation

摘要

An amplifying circuit has an offset calibration mode and a normal mode. The amplifying circuit includes an amplifier having a non-inverting input and an inverting input for receiving, during the normal mode, a first input signal and a second input signal and an output for providing a high speed output signal, wherein the first input signal is a reference voltage or a high speed signal and the second input signal is a high speed signal. The amplifying circuit further includes a first transmission gate and a second transmission gate coupled in series between the non-inverting input and an inverting input that are enabled during the offset calibration mode. A benefit of this approach is that capacitance between the inverting and non-inverting inputs is reduced by the first and second transmission gates being in series. There is further benefit in reducing this capacitance by having each transmission gate receive an enable signal from a different source.