Browse Prior Art Database

Fast and Accurate Switch

IP.com Disclosure Number: IPCOM000087105D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Azzis, D: AUTHOR

Abstract

The drawing shows a current switch which allows a precise current J(O) provided by a current source S to be transferred to an output load R. The switch comprises transistor T(1) and a Darlington transistor pair T(2) and T(3) connected to load R. Conduction of transistor T(1) is controlled by an input voltage. Raising the input voltage causes J(O) to flow through transistor T(1) instead of transistors T(2) and T(3).

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Fast and Accurate Switch

The drawing shows a current switch which allows a precise current J(O) provided by a current source S to be transferred to an output load R. The switch comprises transistor T(1) and a Darlington transistor pair T(2) and T(3) connected to load R. Conduction of transistor T(1) is controlled by an input voltage. Raising the input voltage causes J(O) to flow through transistor T(1) instead of transistors T(2) and T(3).

Diodes D(1) to D(5) are provided to compensate for the negative effects of the parasitic capacitors which exist between nodes B and C, nodes B and D, and node B and the ground node. Also, diodes D(4) and D(5) bias the base of transistor T(3). Diodes D(1), D(2) and D(3) clamp the input voltage and discharge quickly all node B capacitors in the OFF condition of the Darlington arrangement. Thus, the switching time is improved.

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