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US 6,307,430 B1Granted
Noise reduction technique in chopper stabilized amplifier
AssigneeCirrus Logic, Inc.
InventorsAxel Thomsen, Murari Kejariwal, Prasad Ammisetti
Life of this patent
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Abstract
Disclosed is a chopper-stabilized amplifier with current steering used as output switching and to be operated in a low power supply voltage environment.
Claims19
An amplifier circuit comprising:
- a) a first amplifier sub-circuit having a signal input and a clock input, said signal input operable to receive an input signal, and said clock input operable to receive a clock signal, said first amplifier sub-circuit operable to generate first and second output signals, each output signal including a clock component based on said clock signal input;
- b) a second amplifier sub-circuit having an input connected to said first output signal, a feedback path connected to said input signal, and an output, said second amplifier sub-circuit operable to be turned off when said clock component is in a first condition and to collectively form a gain-boosted cascode amplifier with said first sub-circuit to provide an amplified signal at its output when said clock component is in a second condition;
- and
- c) a third amplifier sub-circuit having an input connected to said second output signal, a feedback path connected to said input signal, and an output, said third amplifier sub-circuit operable to be turned off when said clock component is in said second condition and to collectively form a gain-boosted cascode amplifier with said first sub-circuit to provide an amplified signal at its output when said clock component is in said first condition.
1 more element
A chopper stabilized amplifier comprising:
- a) first and second differential voltage inputs;
- b) an input chopper switch having a chopper clock signal input, having inputs connected to said first and second differential voltage inputs, and providing first and second signal path outputs, said input chopper switch operable during one phase of said chopper clock signal to connect said first differential voltage input to said first signal path output and said second differential voltage input to said second signal path output, and during the other phase of said chopper clock signal to connect said second differential voltage input to said first signal path output and said first differential voltage input to said second signal path output;
- c) at least one current-steering amplifier connected to each of said first and second signal path outputs, each of said current-steering amplifiers comprising:
- i) a first amplifier sub-circuit having a signal input for receiving the signal from the respective first or second signal path output and a clock input for receiving a clock signal based on said chopper clock, said first amplifier sub-circuit operable to generate first and second output signals, each output signal including a clock component based on said clock signal input;
- ii) a second amplifier sub-circuit having a signal input connected to said first output signal from said first amplifier sub-circuit, a feedback path connected to said signal input, and an output, said second amplifier sub-circuit operable to be turned off when said clock component is in a first condition and to collectively form a cascode amplifier with said first sub-circuit to provide an amplified signal at its output when said clock component is in a second condition;
- and
- iii) a third amplifier sub-circuit having an input connected to said second output signal from said first amplifier sub-circuit, a feedback path connected to said signal input, and an output, said third amplifier sub-circuit operable to be turned off when said clock component is in said second condition and to collectively form a cascode amplifier with said first sub-circuit to provide an amplified signal at its output when said clock component is in said first condition.
4 more elements
Dependencies are inferred from the claim text.