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Speed/Power Improvement for Large Fan-In Emitter Coupled Logic Decoder Circuits

IP.com Disclosure Number: IPCOM000035362D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 3 page(s) / 104K

Publishing Venue

IBM

Related People

Wendel, DF: AUTHOR [+2]

Abstract

A circuit technique which improves the speed and power consumption of emitter coupled logic (ECL) decoders, as used in bipolar semiconductor arrays, is described. The circuit improvement enables a large number of fan-ins with relatively lower power consumption and improved delay. (Image Omitted)

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Speed/Power Improvement for Large Fan-In Emitter Coupled Logic Decoder Circuits

A circuit technique which improves the speed and power consumption of emitter coupled logic (ECL) decoders, as used in bipolar semiconductor arrays, is described. The circuit improvement enables a large number of fan-ins with relatively lower power consumption and improved delay.

(Image Omitted)

Typically, ECL decoders, as shown in Fig. 1, are used in bipolar arrays to obtain superior speed characteristics. However, relatively high power consumption is necessary when a large number of inputs are implemented. Generally, the speed/power impact of the number of inputs is caused by the input device substrate capacitance, Ccs, as it is charged or discharged during each output transition. Also, the base/collector capacitance, Ccb, when all inputs are switched to a down level voltage, causes a deteriorating effect.

The concept described herein eliminates the speed/power disadvantages for large fan-in decoders. The output signal is generated by the use of an additional inverter 10, as shown in Fig. 2, controlled by the true output of the ECL decoder. The collectors and, therefore, the substrate capacitances of the input devices, are connected to the positive power supply. As a result, the capacitances, experienced in the prior art, do not have to be charged or discharged and consequently will have no impact on the power/speed of the decoder.

The inputs of the decoder are preset at their upward level duri...