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Bidirectional Bipolar FET Interface

IP.com Disclosure Number: IPCOM000084056D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Cassidy, BM: AUTHOR [+2]

Abstract

Described is an improved shunt feedback amplifier for sensing the current flowing in a bit line coupled to a field-effect transistor (FET) memory array. This improved amplifier provides the bit line with a faster re recovery following the write cycle than is available with prior art circuits.

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Bidirectional Bipolar FET Interface

Described is an improved shunt feedback amplifier for sensing the current flowing in a bit line coupled to a field-effect transistor (FET) memory array. This improved amplifier provides the bit line with a faster re recovery following the write cycle than is available with prior art circuits.

The circuit shown comprises a shunt feedback amplifier consisting of transistors T1 and T2, together with a feedback resistor R1 coupled to the base of transistor T1 and between the emitter of transistor T2 and a bit line 10. This bit line 10 has a large capacitance CL associated therewith. A bit line driver circuit T4 is also coupled to bit line 10.

The feedback loop in this circuit including the base-collector circuit of transistor T1 and the base-emitter circuit of transistor T2 is designed to hold the bit line 10 at a specified voltage level, such that a small voltage swing, for example, 15 millivolts on the bit line will be amplified to about 1 volt on the data output line 11 coupled to the emitter of transistor T2.

By coupling the emitter of an additional data driver transistor T3 to the bit line 10, while coupling through resistor Rb the base of transistor T3 to the data out line 11 and to the emitter of transistor T2, and to the collector of another transistor T5 which is coupled in parallel to the driver transistor T4, a faster bit line recovery from the -V level is accomplished.

When data in is a 1, the line 10 will stay in the u...