A clamping circuit for clamping its voltage difference between its first and second terminals includes: an offset operational trans-conductance amplification (OTA) circuit for generating an output current according to a differential mode voltage between its first and second terminals which have a common mode offset voltage; and an amplifier circuit for generating a first terminal voltage according to the output current of the offset OTA circuit, so as to clamp the voltage difference of the clamping circuit to not exceeding a clamping voltage level. The offset OTA circuit includes a first and a second offset OTA sub-circuits, which have common mode offset voltages, and an auxiliary offset circuit. The common mode offset voltage of the offset OTA circuit is equal to a sum of the common mode offset voltages of the first and the second offset OTA sub-circuit and an offset voltage of the auxiliary offset circuit.

An operational amplifier includes a first power voltage end, a second power voltage end, a first-stage operational amplification circuit, and a second-stage operational amplification circuit. The first power voltage end is configured to receive a first power voltage signal, the second power voltage end is configured to receive a second power voltage signal, and a voltage value of the first power voltage signal is greater than a voltage value of the second power voltage signal. The first-stage operational amplification circuit is configured to receive an input signal via a signal input end, and amplify the input signal under enabling control of the first power voltage signal, to generate a first drive signal. The second-stage operational amplification circuit is configured to generate an output signal.