Browse Prior Art Database

Switch Transistor Safe Operating Area Testing and Measuring System

IP.com Disclosure Number: IPCOM000086482D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Perner, FA: AUTHOR

Abstract

A second breakdown (S/B) measuring system is described that applies application safe operating area (SOA) test techniques into a test system that will measure, on a repeatable basis, the S/B limits of bipolar transistors to voltage and current levels that relate directly to the conditions applied to the transistors in their application circuits. A standard flyback test circuit is used with the added features of a controlled current source for the transistor off-drive bias and a S/B protection circuit. The S/B characteristics of a typical switching transistor are described in a companion publication entitled "Second Breakdown Free Switch Transistor" published in the IBM Technical Disclosure Bulletin, Vol. 19, No. 4, September 1976, pages 1308-1309.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Switch Transistor Safe Operating Area Testing and Measuring System

A second breakdown (S/B) measuring system is described that applies application safe operating area (SOA) test techniques into a test system that will measure, on a repeatable basis, the S/B limits of bipolar transistors to voltage and current levels that relate directly to the conditions applied to the transistors in their application circuits. A standard flyback test circuit is used with the added features of a controlled current source for the transistor off-drive bias and a S/B protection circuit. The S/B characteristics of a typical switching transistor are described in a companion publication entitled "Second Breakdown Free Switch Transistor" published in the IBM Technical Disclosure Bulletin, Vol. 19, No. 4, September 1976, pages 1308-1309.

When a controlled current source is used for the turn off base current, the collector sustaining characteristics measured behave ideally, based on simple transistor equations describing avalanche injection. Hence, it is of major importance in the measuring of reverse bias S/B in transistors to use a controlled current source for the base turn off circuit. Controlled current sources are also indicated in the base turn-on circuit and the collector circuit; however, these are relatively minor factors in the repeatability of the measurements.

When a transistor enters S/B, all control of the collector current from the base terminal is lost and the collector-to-emitter voltage collapses to less than ten volts, and, without protection, the collector current would continue to flow and possibly increase until a circuit breaker would open or the transistor would degrade beyond acceptable limits. However, the S/B protection circuit, described below, permits the t...