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Electrically Programmable Transistor Pipes

IP.com Disclosure Number: IPCOM000048188D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Hsieh, CM: AUTHOR [+2]

Abstract

Electrically programmable diffusion pipes (emitter to collector shorts) can be induced in originally good bipolar transistors for use in redundant circuit and other circuit applications.

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Electrically Programmable Transistor Pipes

Electrically programmable diffusion pipes (emitter to collector shorts) can be induced in originally good bipolar transistors for use in redundant circuit and other circuit applications.

Fig. 1 shows a technique, employing current source 1, switch 2 and capacitor 3, for inducing a pipe into NPN transistor T having its base and emitter connected together. A pulse generator (not shown) also could be used to induce the pipe.

With the switch closed. the capacitor charges up to the breakdown voltage BV(CES) of the transistor (e.g., 10V to 30V). At this time, the equivalent AC resistance of the transistor is very small (Fig. 2). Upon opening up the switch, the capacitor discharges through the low resistance transistor very rapidly with high current.

The result is the formation of a localized n type region (pipe) extending through the p type base, thereby shorting the emitter to the collector.

After pipe formation, the base emitter and the base collector junctions have good forward characteristics and the reverse breakdown voltage is small (e.g., 3 to 6 volts). The resistance of the pipe was found to be stable and reproducible for currents in excess of 5 mA. Pipe resistance was found to vary inversely with the capacitance of the capacitor 3 in Fig. 1.

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