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High Voltage FET Driver

IP.com Disclosure Number: IPCOM000078985D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 20K

Publishing Venue

IBM

Related People

Waters, CL: AUTHOR [+2]

Abstract

A high-voltage field-effect transistor (FET) driver circuit especially useful with a metal-alumina-oxide semiconductor (MAOS) product, is described. For MAOS or other nonvolatile devices, a 25-40 volt range is needed to write and to erase the device. These voltages are beyond the gated breakdown voltage of most present FET devices. Although the gate voltage can be increased by process changes, undesirable side effects can occur.

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High Voltage FET Driver

A high-voltage field-effect transistor (FET) driver circuit especially useful with a metal-alumina-oxide semiconductor (MAOS) product, is described. For MAOS or other nonvolatile devices, a 25-40 volt range is needed to write and to erase the device. These voltages are beyond the gated breakdown voltage of most present FET devices. Although the gate voltage can be increased by process changes, undesirable side effects can occur.

This circuit avoids these undesirable side effects, yet increases the voltage to such a level that the breakdown voltage of the devices in the series is not exceeded. The circuit is similar in some respects to a conventional low-voltage driver circuit, and comprises three transistors serially connected between B+ and ground. They are an input transistor T1, a transistor coupled as a diode T2, and a third transistor T3 coupled between transistor T1 and transistor T2. The input signal is applied to the gate of transistor T1 and the output taken between transistors T2 and T3. The gate of this transistor T3 is set to a reference voltage VR, equal to approximately 50% of the impressed B+ voltage.

When transistor T1 is turned on by an input signal on its gate, node 10 between transistors T1 and T3 is brought to ground causing transistor T3 to turn on, thus bringing the output located between the devices T3 and T2 to ground. When transistor T1 is turned off, node 10 rises until it approaches the reference voltage VR appli...