Chopper stabilized amplifier

A chopper stabilized amplifier comprising:

• a non-inverting input pin that receives a first voltage;
• an inverting input pin that receives a second voltage;
• a main amplifier that generates an output signal according to a difference between the first voltage and the second voltage;
• and
• a correction circuit,
• wherein the main amplifier comprises:
• a differential input stage that generates a first current signal, wherein the differential input stage includes a first gm amplifier having a non-inverting input terminal connected to the non-inverting input pin and an inverting input terminal connected to the inverting input pin;
• and
• an output stage that receives the first current signal so as to generate the output signal of the main amplifier,
• wherein the correction circuit comprises:
• a second gm amplifier configured as a fully differential amplifier that amplifies a voltage difference between its non-inverting input terminal and its inverting input terminal, so as to output a differential current signal from its inverting output terminal and its non-inverting output terminal;
• an integrating circuit that integrates a differential input current input to its non-inverting input terminal and its inverting input terminal, that samples and holds the current integrated for a predetermined period, and that generates a differential voltage signal;
• a first selector arranged as an upstream stage of the second gm amplifier, so as to switch a state between:
• (i) a first state in which the non-inverting input pin and the inverting input pin are respectively connected to the inverting input terminal and the non-inverting input terminal of the second gm amplifier;
• and (ii) a second state in which the non-inverting input pin and the inverting input pin are respectively connected to the non-inverting input terminal and the inverting input terminal of the second gm amplifier;
• a second selector arranged downstream from the second gm amplifier, so as to switch a state between:
• (i) a first state in which the inverting output terminal and the non-inverting output terminal of the second gm amplifier are respectively connected to the inverting input terminal and the non-inverting input terminal of the integrating circuit;
• and (ii) a second state in which the inverting output terminal and the non-inverting output terminal of the second gm amplifier are respectively connected to the non-inverting input terminal and the inverting input terminal of the integrating circuit;
• and
• a third gm amplifier that converts the differential voltage signal generated by the integrating circuit into a second current signal, and that superimposes the second current signal on the first current signal.