Self-regulating process-error trimmable PTAT current source
US7236048B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 22, 2005 |
| Grant date | Jun 26, 2007 |
| Priority date | — |
| Expiry date | Dec 17, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F3/30
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A current source for generating a PTAT current using two bipolar transistors with an 1:A emitter area ratio implements a split resistor architecture to cancel mismatch errors in the current mirror of the current source. In one embodiment, a first resistor is coupled to the unit area bipolar transistor and a second resistor is coupled to the A-ratio-area bipolar transistor. The first resistor has a resistance value indicative of the emitter resistance re of the bipolar transistors while the second resistor has a resistance value satisfying the equation re*(lnA−1). In another embodiment, an emitter area trim scheme is applied in a PTAT current source to cancel, in one trim operation, both bipolar transistor area mismatch error and sheet resistance variations. The emitter area trim scheme operates to modify the emitter area of the A-ratio-area bipolar transistor to select the best effective emitter area that provides the most accurate PTAT current.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.