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US 6,734,723 B2Granted
Chopper chopper-stabilized operational amplifiers and methods
AssigneeMaxim Integrated Products, Inc.
InventorsJohan Hendrik Huijsing, Maarten Jeroen Fonderie
Life of this patent
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Abstract
An amplifier topology that combines the use of chopping and chopper stabilization, and may include auto-zeroing to achieve this very low offset. The use of choppers guarantees a very low offset, and moreover, eliminates the so-called 1/f noise. Chopper stabilization is used to avoid the so-called chopper noise associated with chopper amplifiers. The auto-zeroing technique may be used to improve the performance of the chopper-stabilization circuitry. Various exemplary embodiments are disclosed.
Claims42
An amplifier comprising:
- a first chopper;
- a first amplifier stage coupled to an output of the first chopper;
- a second chopper coupled to an output of the first amplifier stage;
- a second amplifier stage coupled to an output of the second chopper;
- a third chopper coupled to the output of the first chopper;
- a third amplifier stage coupled to an output of the third chopper;
- a fourth chopper coupled to an output of the third amplifier stage;
- and,
- an integrator coupled to an output of the fourth chopper, an output of the integrator being coupled to the first amplifier stage to trim the input offset thereof.
6 more elements
An amplifier comprising:
- a first chopper;
- a first amplifier stage coupled to an output of the first chopper;
- a second chopper coupled to an output of the first amplifier stage;
- a second amplifier stage coupled to an output of the second chopper;
- a third amplifier stage coupled to the input of the first chopper;
- a third chopper coupled to an output of the third amplifier stage;
- and,
- a first integrator coupled to an output of the third chopper, an output of the first integrator being coupled to the first amplifier stage to trim the input offset thereof.
5 more elements
An amplifier comprising:
- a first chopper;
- a first amplifier stage coupled to an output of the first chopper;
- a second chopper coupled to an output of the first amplifier stage;
- a third chopper coupled to the output of the first chopper;
- a second amplifier stage coupled to an output of the third chopper;
- a fourth chopper coupled to an output of the second amplifier stage;
- and,
- an integrator coupled to an output of the fourth chopper, an output of the integrator being coupled to the first amplifier stage to trim the input offset thereof;
- the first through fourth choppers, the first and second amplifier stages and the integrator having differential inputs and differential outputs.
6 more elements
An amplifier comprising:
- a first chopper;
- a first amplifier stage coupled to an output of the first chopper;
- a second chopper coupled to an output of the first amplifier stage;
- a second amplifier stage coupled to the input of the first chopper;
- a third chopper coupled to an output of the second amplifier stage;
- and,
- a first integrator coupled to an output of the third chopper, an output of the first integrator being coupled to the first amplifier stage to trim the input offset thereof;
- the first through third choppers, the first and second amplifier stages and the integrator having differential inputs and differential outputs.
5 more elements
A method of stabilizing the offset of an operational amplifier (opamp) having a differential input comprising:
- a) chopping the differential input to the opamp and a differential output of a stage of the opamp;
- b) amplifying a signal responsive to the differential input to the opamp;
- c) chopping the amplified differential signal provided in b);
- d) integrating the chopped amplified differential signal provided in c);
- and,
- e) using the integrated, chopped amplified differential signal provided in d) to trim the input offset of the stage of the opamp.
3 more elements
An amplifier comprising:
- a first chopper coupled to an amplifier input;
- a first amplifier stage coupled to an output of the first chopper;
- a second chopper coupled to an output of the first amplifier stage;
- and,
- a trim circuit coupled directly to the amplifier input and to the first amplifier stage, the trim circuit being responsive to signals on the amplifier input to trim the input offset of the first amplifier stage;
- the first and second choppers and the first amplifier stage have differential inputs and differential outputs.
3 more elements
An amplifier comprising:
- a first chopper coupled to an amplifier input;
- a first amplifier stage coupled to an output of the first chopper;
- a second chopper coupled to an output of the first amplifier stage;
- and,
- a trim circuit coupled to the amplifier input and to the first amplifier stage, the trim circuit being responsive to signals on the amplifier input to trim the input offset of the first amplifier stage, the trim circuit further including an auto-zeroing circuit having an integration function.
2 more elements
Dependencies are inferred from the claim text.