Patent · US Expired

Circuit for increasing the output impedance of an amplifier

US4967104A · kind A · utility

2Cited by

5References

6Claims

0Family size

Assignee

International Business Machines Corporation · US

Inventors

Thomas Ludwig · Sindelfingen, DE
Helmut Schettler · Waldenbuch, DE
Otto Wagner · Edenkoben, DE
Rainer Zuhlke · Leonberg, DE

Key dates

Filing date	Oct 2, 1989
Grant date	Oct 30, 1990
Priority date	—
Expiry date	Oct 2, 2009

Classification

Technology area (CPC H)Electricity
CPC primaryH03K19/00361
WIPO fieldBasic communication processes
WIPO sectorElectrical engineering

Abstract

The present invention teaches an arrangement for increasing the output impedance of a power amplifier coupled to a capacitively loaded line during the switching of power levels by the amplifier on the line. The arrangement of the invention reduces undesired noise voltage during switching. The present invention achieves this end by using a control circuit composed of a differential amplifier which has one input fed from the junction of an impedance resistor and a transistor that simulate the power stage transistor in the power amplifier being switched. This control circuit provides control voltage outputs to power control transistors which are connected to and control the speed of the power stage transistors used to change and discharge the capcitively loaded line.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.