Patent · US Expired

Circuit arrangement comprising a phototransistor

US4688071A · kind A · utility

6Cited by

5References

9Claims

0Family size

Assignee

Siemens Aktiengesellschaft · DE

Inventors

Jenoe Tihanyi · Tauberbischofsheim, DE
Christine Fellinger · Unterhaching, DE
Ludwig Leipold · Munich, DE

Key dates

Filing date	Oct 22, 1984
Grant date	Aug 18, 1987
Priority date	—
Expiry date	Oct 22, 2004

Classification

Technology area (CPC H)Electricity
CPC primaryH01L2924/13091
WIPO fieldBasic communication processes
WIPO sectorElectrical engineering

Abstract

In a circuit arrangement having a phototransistor, in order to increase the inverse voltage strength of the phototransistor, a resistor that carries off the collector-base inverse current generally lies between the base zone and the emitter zone of the phototransistor. This resistor should be as large as possible given illumination in order to increase the current gain. The resistor according to the invention is formed by the drain-source path of an IGFET of depletion type whose gate terminal is at a fixed potential. The IGFET is conductive in the unilluminated condition of the phototransistor. During illumination, its resistance increases given an increasing photocurrent.

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