Active auto zero circuit for time continuous open loop amplifiers
US6583660B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 25, 2001 |
| Grant date | Jun 24, 2003 |
| Priority date | — |
| Expiry date | May 25, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45658
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An active offset cancellation circuit for an open loop differential amplifier is disclosed. The amplifier is operated on a two-phase clock where the normal operation occurs on the first phase and offset detection and cancellation occurs on the second phase. On the second phase, the offset cancellation circuit measures the offset created by the amplifier when both differential inputs are connected to a common source. The circuit then adjusts a bias current and stores this adjustment to cancel offset during the operational phase of the amplifier. During the operational phase, the first phase of the clock, the stored adjustment is used to bias the current in one of the two input stages of the amplifier, canceling any offset imparted by the amplifier circuitry. One each clock cycle, any additional offset is similarly detected and canceled.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.