Differential amplifier with rail-to-rail input capability and controlled transconductance
US4555673A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 1984 |
| Grant date | Nov 26, 1985 |
| Priority date | — |
| Expiry date | Apr 19, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/45708
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A differential amplifier operable between a pair of supply voltages that define a rail-to-rail supply range contains a pair of differential portions (20 and 22) that together provide representative signal amplification across the supply range, although neither differential portion individually does so. A current control (24) regulates operating currents (I.sub.N and I.sub.p) for the differential portions in such a way that the amplifier transconductance can be controlled in a desired manner as the common-mode part (V.sub.CM) of the amplifier input signal (V.sub.I+ and V.sub.I-) varies across the supply range. The transconductance is typically controlled to be largely constant. A summing circuit (26) selectively combines internal currents (I.sub.A, I.sub.B, I.sub.C, and I.sub.D) from the differential portions to generate at least one output signal (I.sub.O+ and I.sub.O-) representative of the input signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.