Offset calibration and precision hysteresis for a rail-rail comparator with large dynamic range
US7973569B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 17, 2010 |
| Grant date | Jul 5, 2011 |
| Priority date | — |
| Expiry date | Mar 17, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/45699
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A rail-rail comparator having an input stage with independent positive and negative differential voltage offset compensation tracks changes in Gm (transconductance) of the input stage. By tracking the changes in Gm (transconductance) of the input stage, hysteresis of the rail-rail comparator becomes insensitive to the input common mode voltage. A two-stage rail-rail comparator may be used for adding hysteresis to a second stage. The first stage of the two-stage rail-rail comparator operates at substantially unity gain. The second stage of the two-stage rail-rail comparator operates as a regular high gain amplifier with hysteresis. Additional circuitry tracks the Gm (transconductance) change of the first stage to make the second stage hysteresis insensitive to the input common mode voltage at the first stage. This also makes it easier to create a programmable hysteresis that is accurate over all input voltage values.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.