Low voltage operational amplifier input stage and method
US5734296A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 19, 1996 |
| Grant date | Mar 31, 1998 |
| Priority date | — |
| Expiry date | Mar 19, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45182
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Low voltage operational amplifier (10) operates in a voltage range of one to eight volts over a temperature range of 0.degree. to 70.degree. centigrade. Op amp input stage (12) uses N-channel depletion-mode MOSFETs to provide amplification of the differential input and maintain constant transconductance. Source follower MOSFET (13) provides unity gain in transferring the AC signal, STAGE-1 OUTPUT, to the base of current sinking transistor (18). Sink control circuit (14) and source control circuit (22) generate the base drive currents for transistors (18) and (24). The signal at the output of MOSFET (13) either causes the sink transistor (18) to sink current or the signal to be transposed by means of a translinear loop (16) and causes the source transistor (24) to source current. An output stage provides approximately fifty milliamps of current drive and is quiescent until the output driver is selected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.