Patent ID: 9391571
Filing Date: 2016-07-12
CPC Classification: H03F

Claim Text:
1. A chopper-stabilized amplifier comprising: a first operational transconductance amplifier; a first chopper circuit coupled to an input of the first operational transconductance amplifier for chopping an input signal and applying a chopped input signal to the input of the first operational transconductance amplifier; a second chopper circuit coupled to an output of the first operational transconductance amplifier for chopping an output signal produced by the first operational transconductance amplifier; and a symmetrical passive RC notch filter with two cutoff frequencies having an input coupled to an output of the second chopper circuit to filter a chopped output signal produced by the second chopper circuit to notch filter ripple voltages received from the output of the second chopper circuit wherein the symmetrical passive RC notch filter includes first and second inputs, wherein the symmetrical passive RC notch filter includes first and second outputs, and wherein the symmetrical passive RC notch filter includes: a first path including a first resistor coupled between the first input and a first node, and a second resistor coupled between the first node and a second node; a second path including a first capacitor coupled between the first input and a third node, and a second capacitor coupled between the third node and the second node; a third path including a third resistor coupled between the second input and a fourth node, and a fourth resistor coupled between the fourth node and a fifth node; a fourth path including a third capacitor coupled between the second input and a sixth node, and a fourth capacitor coupled between the sixth node and the fifth node; a fifth resistor coupled between the third node and the sixth node and a fifth capacitor coupled between the first node and the fourth node.