At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Lawrence A Walter

Bernard L Morris

Jeffrey J Nagy

An integrated circuit comprises a resistor that is formed by doping a semiconductor region that is defined by a layer, typically polysilicon, that also defines the gate electrode of field effect transistors in the integrated circuit. The well-controlled linewidth of features defined in this layer provides for tight resistor tolerance, and also allows the value of the resistor to track changes in other features defined by this layer.

Integrated circuit resistor

A field effect transistor circuit generates a reference current that can obtain a desired temperature coefficient. The circuit is self-compensatory with respect to process variations, in that a 'slow' process will produce a higher than normal current, while a 'fast' process will give a lower one. This results in a tight spread of slew-rate, gain, gain-bandwidth, etc. in opamps, comparators, and other linear circuits. A simple adjustment in the circuit allows the temperature coefficient to be made positive or negative if so desired. An illustrative circuit is shown for CMOS technology, but can be applied to other field effect technologies.

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Lower Macungie Township, PA, United States of America

Lawrence A Walter