Rail to rail operational amplifier input stage
US5414388A · kind A · utility
8Cited by
3References
5Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Mar 3, 1994 |
| Grant date | May 9, 1995 |
| Priority date | — |
| Expiry date | Mar 3, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45471
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An op-amp incorporates an input stage composed of two complementary long-tailed transistor pairs driven in parallel from the input terminals. A bias supply circuit provides the tail currents which are proportioned so that the total tail current adds up to a constant sum. The bias circuit proportions the tail currents, relative to the common mode voltage, so that at least one long tailed pair will function even when the common mode is driven to the supply rail potential. The bias supply current includes cascode connected transistors to provide the tail currents and the input circuit includes active clamping transistors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.