CHOPPER STABILIZED AMPLIFIER

摘要

A main amplifier generates an output signal SOUT according to a difference between first and second voltages VP and VN. A first gm amplifier is arranged as a differential input stage. A second, fully differential, gm amplifier amplifies a voltage difference between its non-inverting and inverting input terminals, and outputs a differential current signal I3N/I3P via its inverting and non-inverting output terminals. An integrator integrates a differential input current I4P/I4N input via its non-inverting and inverting input terminals, and samples and holds the signal every predetermined period, to generate a differential voltage signal. A first selector is arranged as an upstream stage of the second gm amplifier, and outputs the differential input signal without change or otherwise after swapping. A second selector is arranged as a downstream stage of the second gm amplifier, and outputs the signal I3N/I3P output from the second gm amplifier without change or otherwise after swapping.

主权项

1. 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; andan 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; anda 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.