Chopping technique for continuous time sigma-delta ADCs without Q-noise folding
AssigneeTexas Instruments Incorporated
InventorGanesh Balachandran
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Abstract
A chopping transconductor includes an transconductor input stage coupled with input signals of the chopping transconductor; a chopping switch coupled with an output of the transconductor input stage, the chopping switch having a switch output; and a cascode transistor, wherein the switch output is coupled to an output of the chopping transconductor through the cascode transistor. The chopping transconductor may be used in an analog-to-digital converter to isolate chopping switches from junctions with quantization noise.
Claims20
A chopping transconductor comprising:
- an transconductor input stage coupled with input signals of the chopping transconductor;
- a chopping switch coupled with an output of the transconductor input stage, the chopping switch having a switch output;
- and
- a first output cascode transistor, wherein the switch output is coupled to a chopping transconductor output through the first output cascode transistor.
A method of processing a signal in an analog-to-digital converter, comprising:
- receiving an input signal,
- amplifying the input signal to produce a first output signal,
- chopping the first output signal to produce a second output signal;
- coupling the second output signal through an output cascode transistor to a summing junction;
- and
- coupling a quantization feedback signal to the summing junction.
An analog to digital converter comprising:
- a chopping transconductor comprising:
- an transconductor input stage coupled with input signals of the chopping transconductor;
- a chopping switch coupled with an output of the transconductor input stage, the chopping switch having a switch output;
- and
- a first output cascode transistor, wherein the switch output is coupled to a chopping transconductor output through the first output cascode transistor;
- a summing junction coupled with the chopping transconductor output;
- and
- a quanitizer providing a feedback signal coupled with the summing junction.
Dependencies are inferred from the claim text.