International Business Machines Corporation

Walter S Klara

Jack A Dorler

Dennis C Banker

Frank A Montegari

Theodore William Kwap

Frank M Masci

Yuen H Chan

Joseph M Mosley

Allan Harvey Dansky

Steven John Zier

Paul David Hendricks

James R Struk

Robert A Rasmussen

Adrian Zuckerman

Francesco M Masci

Gordon S Sager

James E Dickerson

Victor Marcello

Tore A Carlson

A high speed bipolar multiplexer circuit adds less than ten picoseconds delay to the data or test paths. The multiplexer circuit incorporates a low gain linear amplifier which is completely stable and compensates for any level losses through the input emitter followers. The minimal delay introduced in the system data paths and the good isolation between system data inputs and test data inputs matches the performance of the logic and memory circuits of the chips in which multiplexer circuits are incorporated.

High speed multiplexer

Relatively constant current sources and current mirrors are formed with vertical bipolar transistors operated in the inverse mode. In one embodiment of the invention, an integrated circuit current mirror includes a dual collector vertical NPN bipolar transistor having first and second regions of one conductivity type defining first and second collector regions, respectively, formed within a common third region of opposite conductivity type defining the base of the transistor. The third region is formed within a fourth region defining the emitter of the transistor. The structure of the dual collector vertical transistor is very compact since the two collectors share the same base region which is embedded in a common emitter (inverse collector) pocket. The 'inverse' mode vertical transistor can function as a relatively constant current source with a voltage drop (VCEi) across its collector-to-emitter which is substantially less than that of a bipolar transistor operated in a normal mode. Transistors embodying the invention may be used to provide relatively constant current sources to numerous utilization means, such as logic or analog circuits. Due to the low VCEi of the 'inverse' mode transistor, the resultant circuits can be operated at a lower operating voltage than prior art circuits. This results in a decrease of power dissipation.

Integrated circuit employing inverse transistors

A zero power decoder/driver circuit for high performance array chips dissipates zero power when in the deselected state. The decoder/driver circuit is a complementary bipolar circuit comprising a first bipolar transistor of a first conductivity type having its base connected to a down level decoded output of a first level decoder and its emitter connected to an up level decoded output of said first level decoder. The decoder/driver circuit is selected by a predetermined voltage differential across the base/emitter circuit of the first transistor. A diode-connected second bipolar transistor of a second conductivity type is connected to the collector of said first bipolar transistor. A line driver third bipolar transistor of the second conductivity type is connected to a load resistor and mirrors current flowing in said second bipolar transistor. When the second state decoder is deselected, no current flows in the second bipolar transistor of second conductivity type and, therefore, no current is mirrored into the third bipolar transistor of second conductivity type, thus resulting in zero power dissipation. Since only one word line and one bit column are selected at a time, total power dissipation can be substantially reduced.

Zero power decoder/driver

This invention contemplates the provision of a noise immune integrated circuit receiver in which the voltage reference to one side of an emitter-coupled current switch moves in response to the input signal, in a direction opposite the input signal. This provides the gate with a threshold hysteresis, making it immune to noise without requiring a large swing in input signal.

High noise tolerance receiver

A BIFET logic circuit for quickly switching an output line from a high level to a reference level. The BICMOS circuit comprises a push-pull circuit including a first bipolar transistor for driving current into an output line, and a second bipolar transistor for sinking current from the output line; a CFET logic circuit for performing a logic function and including at least one N type FET for providing current to the base of the second bipolar transistor when a set of input lines to the CFET circuit has a first set of predetermined values; and a resistive means for connecting one of the source or drain of the at least one NFET to a power supply to provide a source of base current to the second bipolar transistor, even when the output line drops in voltage. This circuit is especially advantageous for driving low threshold CFET circuits. In a preferred embodiment, the circuit further includes a device for preventing a voltage differential of more than a predetermined amount between the base and emitter of the first bipolar transistor, to thereby ensure proper push-pull operation of the bipolar transistors.

BIFET logic circuit

An on-chip apparatus for generation of timing signals for a large scale integrated (LSI) chip or semiconductor memory array is disclosed. This apparatus may be used both during the production testing of the memory and during normal functional operation. In the testing environment it allows use of much less expensive peripheral test equipment, while also providing for much greater accuracy in determination of whether or not the memory array meets its timing specification. Use during normal functional operation (subsequent to use in the test environment) provides for a guarantee of defect free operation.

Self contained array timing

Disclosed is a means for enhancing logic circuit performance and more particularly, for enhancing the switching speeds of a variety of logic circuits. What is involved is the insertion of a so called 'snap' or enhancement transistor connected to a common node defining an output of a basic logic circuit. In one example, the emitter of this 'snap' transistor is connected to an output node in the circuit, which in conventional practice would be charged during an upgoing transition by a fixed RC time constant. In accordance with the present improvement, however, the 'snap' transistor, due to charge stored therein, remains conducting--although the associated logic device is turned off. This current discharges as reverse base current and the output provides what appears to be an inductive voltage spike. The effect is that a temporary source of current is available to charge the common node. As a result, the transition time involved in going from one voltage level to another at the output node is substantially reduced.

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Hopewell Junction, NY, United States of America

Walter S Klara