Tail-current steering circuit and method for rail-to-rail operational amplifier input stage
US7411453B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 19, 2007 |
| Grant date | Aug 12, 2008 |
| Priority date | — |
| Expiry date | Feb 21, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45476
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An amplifier includes first and second pairs of differentially coupled input transistors. The first current mirror generates a reference current which is mirrored by a second current mirror to produce a mirrored reference current. Current steering circuitry steers the mirrored reference current as a first tail current through the first pair when a common mode voltage associated with a differential input voltage exceeds a first reference voltage. A first portion of the mirrored reference current flows from the first current steering circuitry when the common mode voltage is greater than the first reference voltage to produce a second tail current for the second pair. A second portion of the mirrored reference current is fed back to an output of the first current mirror and summed with the reference current so as to reduce the second portion when the common mode voltage is greater than the first reference voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.