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US 8,680,922 B2Granted
Rail-to rail input circuit
AssigneeAnalog Devices, Inc.
InventorQuan Wan
Life of this patent
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Abstract
A power-efficient, rail-to-rail input circuit includes two differential pairs, one having devices of a first threshold voltage and one having devices of a second, different threshold voltage. In various embodiments, the two differential pairs receive a differential input in parallel and are supplied a tail current, which a control circuit steers between the pairs in accordance with a common-mode level of the input.
Claims22
A rail-to-rail differential input circuit comprising:
- a first differential pair configured to receive a differential input, the first differential pair comprising first devices having a first threshold voltage;
- a second differential pair configured to receive the differential input in parallel with the first differential pair, the second differential pair comprising second devices having a second threshold voltage different from the first threshold voltage;
- a tail current source configured to provide a tail current shared between the first and second differential pairs;
- and
- a control device, connected between common source or common emitter nodes of the first and second differential pairs, configured to steer the tail current between the first and second differential pairs in accordance with a common-mode level of the differential input.
2 more elements
A method for processing a differential input voltage having a rail-to-rail common-mode range, the method comprising:
- supplying a tail current to be shared between a first differential pair comprising first devices having a first threshold voltage and a second differential pair comprising second devices having a second threshold voltage;
- sharing the tail current between the first and second differential pairs;
- and
- steering the tail current to at least one of the first and second differential pairs in accordance with a common-mode level of the differential input voltage.
1 more element
Dependencies are inferred from the claim text.