Electronic switches and switch networks

US3931475A · kind A · utility

Assignee

• Licentia Patent-Verwaltungs-GmbH · DE

Inventors

• Erich Bachle · Erbach, DE
• Helmut Kliem
• Bernhard Rall · Ulm, DE

Key dates

• Filing date: Dec 17, 1974
• Grant date: Jan 6, 1976
• Expiry date: Dec 17, 1994

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03K17/68
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

In an electronic switching device for use as the switching component of a switching network in a telephone central office, the device being composed of a switching transistor connected in series in the signal conduction path for switched signals and a controllable impedance connected in a shunt branch, the switching transistor, in its conductive state, having a low series resistance and an associated high shunt resistance, and, in its blocking state, having a high series resistance and an associated low shunt resistance, the shunt branch is composed of a control transistor having a control voltage applied to its base, having its collector connected to the base of the switching transistor, and having its emitter connected to the switching transistor through a resistor to constitute a feedback path for the switching transistor, a voltage-dependent resistor connected to the base of the switching transistor, and suitable sources of operation voltages, the voltages and characteristics of the voltage-dependent resistor being selected to be such that when the switching transistor is conductive, the control transistor operates conductively in its active region and the voltage-dependent res…