Patent ID: 7518440

Claim:
A chopper-stabilized amplifier comprising: (a) a first chopping/notch-filtering circuit including (1) a first amplifier, (2) first input chopper circuitry coupled to an input of the first amplifier for chopping an input signal and applying the chopped input signal to the input of the first amplifier, and first output chopper circuitry coupled to an output of the first amplifier for chopping an output signal produced by the first amplifier, the first input chopper circuitry and the first output chopper circuitry being clocked by a first clock signal, and (3) a first switched capacitor notch filter having an input coupled to an output of the first output chopper circuitry and performing an integrate and transfer function on a chopped output signal produced by the first output chopper circuitry to filter a chopped output signal produced by the first output chopper circuitry by operating synchronously with a chopping frequency of the first clock signal to notch-filter noise signals on the chopped output signal of the first output chopper circuitry that otherwise would cause output ripple voltages on an output of the first switched capacitor notch filter, the first switched capacitor notch filter being clocked by a second clock signal; and (b) a second chopping/notch-filtering circuit including (1) a second amplifier, (2) second input chopper circuitry coupled to an input of the second amplifier for chopping the input signal and applying that chopped input signal to the input of the second amplifier, and second output chopper circuitry coupled to an output of the second amplifier for chopping an output signal produced by the second amplifier, the second input chopper circuitry and the second output chopper circuitry being clocked by a third clock signal, and (3) a second switched capacitor notch filter having an input coupled to an output of the second output chopper circuitry and performing an integrate and transfer function on a chopped output signal produced by the second chopper circuitry to filter a chopped output signal produced by the second output chopper circuitry by operating synchronously with a chopping frequency of the third clock signal to notch-filter noise signals on the chopped output signal of the second output chopper circuitry that otherwise would cause output ripple voltages on an output of the second switched capacitor notch filter, the second switched capacitor notch filter being clocked by a fourth clock signal; and (d) the outputs of the first and second switched capacitor notch filters being coupled together so as to provide a combined output signal that updates a load coupled to the outputs of the first and second switched capacitor filters at a frequency that is 4 times the frequency of the second clock signal.