Browse Prior Art Database

Current-Tracking Mechanism

IP.com Disclosure Number: IPCOM000059925D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Smith, CD: AUTHOR

Abstract

Improved current tracking mechanisms can be implemented for dual or single rail current switched circuits by using current-limiting resistors (CLRs) of the type disclosed in the IBM Technical Disclosure Bulletin, 25, 4595-4596 (February 1983). Use of these devices allows lower supply voltages for cascode circuits and provides a novel and simple mechanism for offset voltage tracking. Fig. 1 is a schematic diagram of a generalized current switched circuit having internal logic current switches 1, which are connected to inputs 3 and voltage references 5 (for single rail only). The switches are connected to the positive supply terminal +V via offsetting resistors 7, and to the negative supply terminal -V via current-limiting device 9. In prior arrangements as shown in Fig.

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Current-Tracking Mechanism

Improved current tracking mechanisms can be implemented for dual or single rail current switched circuits by using current-limiting resistors (CLRs) of the type disclosed in the IBM Technical Disclosure Bulletin, 25, 4595-4596 (February 1983). Use of these devices allows lower supply voltages for cascode circuits and provides a novel and simple mechanism for offset voltage tracking. Fig. 1 is a schematic diagram of a generalized current switched circuit having internal logic current switches 1, which are connected to inputs 3 and voltage references 5 (for single rail only). The switches are connected to the positive supply terminal +V via offsetting resistors 7, and to the negative supply terminal -V via current-limiting device 9. In prior arrangements as shown in Fig. 1, two types of current- limiting devices have been employed: conventional resistors and current mirrors, the latter yielding less variation of the offset voltage across the offsetting resistors from circuit to circuit than a resistor used as the current-limiting device
9. When a current mirror is used, the offset voltage variation for circuits on different chips is due to the variations in the resistances of the current mirror references and the offsetting resistors. These variations result from variations in the diffusions. The improved tracking mechanism is provided by replacing the offsetting resistors 7 and the current limiting device 9 with current- limiting resisto...