Input compensation circuit for superbeta transistor amplifier
US4757274A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 14, 1987 |
| Grant date | Jul 12, 1988 |
| Priority date | — |
| Expiry date | Jan 14, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2200/261
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An improved input current compensation circuit is provided for a dual branch amplifier, particularly an amplifier employing superbeta transistors. The compensation circuit has a superbeta compensation transistor which is matched with the superbeta amplifier transistors, a bipolar transistor connected across the superbeta transistor in a manner analogous to a voltage limiting circuit in the amplifier section, and current sources which provide operating currents to both the superbeta and bipolar compensation transistors. The base current of the superbeta compensation transistor is mirrored to the bases of the superbeta amplifier transistors, and the superbeta transistors, bipolar transistor and current sources in the compensation section are scaled relative to corresponding elements in the amplifier section so that the superbeta amplifier transistor base currents are substantially compensated by current mirrored from the compensation circuit. A negative feedback circuit is provided to keep the superbeta compensation transistor in its linear operating region, and current sources in the compensation section are selected to mitigate second-order errors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.