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Compensated Current Switch Emitter Follower

IP.com Disclosure Number: IPCOM000042708D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Dorler, JA: AUTHOR [+2]

Abstract

The compensated current switch functions to reduce output level variations due to Vcc changes. It is common practice in ECL circuits to use an emitter constant current source to provide common-mode power supply noise rejection (noise immunity). In addition to this, we have found that the use of collector clamps, as shown, provides improved characteristics for little circuit and area overhead. The circuit utilizes UP and DOWN level clamps at the collectors of the current switch to reference the voltage swing to VR, T1, S1, S2, S3, and R1. This results in a great deal of positive power supply immunity (WI1) and minimizes signal swings for a given noise immunity. Higher performance at the circuit level (N30%) is thereby provided.

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Compensated Current Switch Emitter Follower

The compensated current switch functions to reduce output level variations due to Vcc changes. It is common practice in ECL circuits to use an emitter constant current source to provide common-mode power supply noise rejection (noise immunity). In addition to this, we have found that the use of collector clamps, as shown, provides improved characteristics for little circuit and area overhead. The circuit utilizes UP and DOWN level clamps at the collectors of the current switch to reference the voltage swing to VR, T1, S1, S2, S3, and R1. This results in a great deal of positive power supply immunity (WI1) and minimizes signal swings for a given noise immunity. Higher performance at the circuit level (N30%) is thereby provided. Vcc power supply voltages in excess of VBE + VF can be expressed as additional noise immunity for WI.

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