A programmable gain amplifier includes a sampling circuit, a source follower, a first capacitor and an error amplifier. The sampling circuit is configured to perform correlated double sampling on an input signal using a reference voltage. The first capacitor is connected between the sampling circuit and the source follower. The error amplifier is connected between an input terminal of the source follower and an output terminal of the source follower. The error amplifier is configured to reset a voltage of the output terminal of the source follower to the reference voltage during a source follower reset operation.