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Transistor for Circuit Protection Having Laterally Extended Collector Region Forming Series-Resistor Isolating Circuit From High Voltage

IP.com Disclosure Number: IPCOM000047037D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Bellos, S: AUTHOR [+5]

Abstract

A transistor is connected to conduct between an electrical pad and ground when a high voltage appears at the pad, and the collector region of the transistor is extended laterally and connected at two opposite points to form a series resistor in the normal circuit path. When a high voltage occurs at the pad and the transistor turns on, voltage drops along the width of the collector region isolate the circuit from the voltage at the pad. Background Some semiconductor devices are easily damaged by voltages that may occur with static charges in ordinary handling, and it is common to connect a negative resistance device across terminals where this voltage may appear. This device is normally non-conducting but turns on when the voltage rises to a predetermined level.

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Transistor for Circuit Protection Having Laterally Extended Collector Region Forming Series-Resistor Isolating Circuit From High Voltage

A transistor is connected to conduct between an electrical pad and ground when a high voltage appears at the pad, and the collector region of the transistor is extended laterally and connected at two opposite points to form a series resistor in the normal circuit path.

When a high voltage occurs at the pad and the transistor turns on, voltage drops along the width of the collector region isolate the circuit from the voltage at the pad. Background Some semiconductor devices are easily damaged by voltages that may occur with static charges in ordinary handling, and it is common to connect a negative resistance device across terminals where this voltage may appear. This device is normally non-conducting but turns on when the voltage rises to a predetermined level. When the device is on, the excessive voltage is dropped across the series resistance between the pad and the device. One common device of this type is a bipolar transistor that has its base terminal unconnected and has its emitter and collector terminals connected to conduct between ground and the point that is to be protected. At a predetermined high voltage, minority carriers from the collector region flow across the base-emitter junction and turn on the transistor. Implementation The drawing shows a region of a semiconductor chip that has a metal pad 2 where a static c...