Low noise, high CMRR and PSRR input buffer

A rail-to-rail buffer receiving a differential input signal and generating a differential output signal includes first and second amplifier circuits configured in a pseudo differential buffer structure and first and second comparators coupled to compare the respective part of the differential input signal and a first voltage and to generate select signals. Each of the first and second amplifier circuits includes first and second complementary differential input stages and the first and second comparators generate respective select signals to turn on only one of the first or the second differential input stage in each amplifier circuit depending on a value of the respective part of the differential input signal. In operation, the first and second complementary differential input stages of each amplifier circuit not being turned on at the same time.