Simultaneous filtering and compensation circuitry and method in chopping amplifier

A method of operating a chopper-stabilized amplifier comprising:

• (a) performing a chopping/amplifying operation on an input signal by chopping the input signal in response to a first clock signal, applying the chopped input signal to an input of a first amplifier, and chopping an output signal produced by the first amplifier by means of output chopper circuitry in response to the first clock signal to produce a chopped output signal;
• and
• (b) operating switched capacitor notch filter circuitry having an input coupled to receive the first chopped output signal by performing an integrate and transfer function on the chopped output signal synchronously with the first clock signal and also in response to a second clock signal to notch-filter noise signals in the first chopped output signal, by
• (1) coupling a first compensation capacitor between an output of the chopper-stabilized amplifier and a first output of the output chopper circuitry by means of a first switch in response to the second clock signal and coupling a second compensation capacitor between the output of the chopper-stabilized amplifier and a first input of a second amplifier by means of a second switch in response to the second clock signal, and
• (2) coupling the first compensation capacitor between the output of the chopper-stabilized amplifier and the first input of the second amplifier by means of a third switch in response to a third clock signal which is out of phase with the second clock signal and coupling the second compensation capacitor between the output of the chopper-stabilized amplifier and the first output of the output chopper circuitry by means of a fourth switch in response to the third clock signal.

A chopper-stabilized amplifier comprising:

• (a) means for chopping an input signal in response to a first clock signal, applying the chopped input signal to an input of a first amplifier, and means for chopping an output signal produced by the first amplifier in response to the first clock signal to produce a chopped output signal;
• and
• (b) switched capacitor notch filter circuitry means having an input coupled to receive the first chopped output signal for performing an integrate and transfer function on the chopped output signal synchronously with the first clock signal and also in response to a second clock signal to notch-filter noise signals in the first chopped output signal, including
• (1) means for coupling a first compensation capacitor between an output of the chopper-stabilized amplifier and a first output of the output chopper circuitry in response to the second clock signal and means for coupling a second compensation capacitor between the output of the chopper-stabilized amplifier and a first input of a second amplifier in response to the second clock signal, and
• (2) means for coupling the first compensation capacitor between the output of the chopper-stabilized amplifier and the first input of the second amplifier in response to a third clock signal which is out of phase with the second clock signal and means for coupling the second compensation capacitor between the output of the chopper-stabilized amplifier and the first output of the output chopper circuitry in response to the third clock signal.