Input buffer and a method for reducing a signal amplitude dependency of said input buffer

An input buffer for an analog-to-digital converter, ADC, configured for receiving an input signal and for outputting an output signal, the input buffer comprising:

• at least one n-channel metal-oxide-semiconductor, nMOS, transistor and at least one p-channel MOS, pMOS, transistor, wherein the at least one nMOS transistor and the at least one pMOS transistor are arranged in a push-pull configuration such that the input signal is fed to gates of the at least one nMOS transistor and the at least one pMOS transistor and the output signal is taken from sources of the at least one nMOS and the at least one pMOS transistors;
• a first varactor connected between a gate of the at least one nMOS transistor and a first biasing voltage potential;
• a second varactor connected between a gate of the at least one pMOS transistor and a second biasing voltage potential,
• wherein the first varactor and the second varactor are configured to reduce a signal amplitude dependency of a capacitance of the input buffer.