Clamping circuit and offset OTA circuit thereof

A clamping circuit for clamping a voltage difference between a first terminal and a second terminal of the clamping circuit so as not to exceed a clamping voltage level, comprising:

• an offset operational trans-conductance amplification (OTA) circuit configured to generate an output current at its output terminal according to a differential mode voltage between a first input terminal and a second input terminal, wherein a common mode offset voltage is present between the first input terminal and the second input terminal thereof, wherein the first input terminal and the second input terminal of the offset OTA circuit are respectively coupled to the first terminal and the second terminal of the clamping circuit;
• and
• an amplification stage circuit coupled between the output terminal and the first input terminal of the offset OTA circuit, configured to generate a first terminal voltage at the first terminal of the clamping circuit according to the output current of the offset OTA circuit, so as to clamp the voltage difference of the clamping circuit to not exceed the clamping voltage level;
• wherein the clamping voltage level corresponds to the common mode offset voltage of the offset OTA circuit;
• wherein the offset OTA circuit includes:
• a first offset OTA sub-circuit having a common mode offset voltage between its first input terminal and its second input terminal, configured to generate the output current of the offset OTA circuit at the output terminal of the offset OTA circuit based on a differential mode voltage between the first input terminal and the second input terminal thereof;
• a second offset OTA sub-circuit having a common mode offset voltage between its first input terminal and its second input terminal, configured to generate the output current of the offset OTA circuit at the output terminal of the offset OTA circuit based on a differential mode voltage between the first input terminal and the second input terminal thereof;
• and
• an auxiliary offset circuit configured to generate an auxiliary offset voltage between the first offset OTA sub-circuit and the second offset OTA sub-circuit;
• wherein plural input terminals of the first offset OTA sub-circuit, plural input terminals of the second offset OTA sub-circuit, and plural input terminals of the auxiliary offset circuit are connected in series, such that the common mode offset voltage of the offset OTA circuit equals a sum of the common mode offset voltage of the first offset OTA sub-circuit, the common mode offset voltage of the second offset OTA sub-circuit, and the auxiliary offset voltage.