Wide band amplifier with current mirror feedback to bias circuit
US4897616A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 25, 1988 |
| Grant date | Jan 30, 1990 |
| Priority date | — |
| Expiry date | Jul 25, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F1/307
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A wideband integrated circuit amplifier includes a pair of current mirror circuits sensing emitter currents of NPN and PNP transistors in the amplifier output stage. A pair of current mirror circuits divide the emitter currents, respectively, by a factor of 20. The current mirror output currents are summed, current splitter directs approximately 1/20 of the summed mirror currents through a transistor, the collector of which is coupled to the gate electrode of a field effect input transistor of a bias control circuit, to produce a scaled down feedback current. A high impedance current source is connected to the collector of the transistor. The bias circuit adjusts the DC bias voltage applied between the base electrodes of the transistors to cause the scaled down feedback current to equal the constant current. A very small compensation capacitor produces a low frequency pole that prevents the bias circuit from interfering with high frequency performance characteristics of a wide band amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.