Browse Prior Art Database

Linear Current Switch

IP.com Disclosure Number: IPCOM000089013D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Gersbach, JE: AUTHOR

Abstract

This article describes a linear current switch which eliminates the nonlinear gain characteristics found in such current switches, and thus provides linear amplifications in a normal fashion with the improved performance to be especially found in digital-to-analog converters.

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Linear Current Switch

This article describes a linear current switch which eliminates the nonlinear gain characteristics found in such current switches, and thus provides linear amplifications in a normal fashion with the improved performance to be especially found in digital-to-analog converters.

The circuit shown in the figure is basically comprised of a series of PNP and NPN current switches. A current switch comprised of transistors T1 and T2 having load resistors R1 and R2, and outputs 01 and 02 have their bases coupled to the positive and the negative poles, respectively, the voltage input which drives simultaneously, with transistors T1 and T2, transistors T5, T3, and T6 and T4, respectively. The current switch comprised of transistors T1 and T2 utilizes transistors T8 and T9 as the current source thereof, while the current switch comprised of transistors T5 and T6 utilizes as a current source the transistor T7 whose base is coupled in common with transistor T8.

The current switch comprised of transistors T3 and T4 utilizes transistor T10 as its current source, and transistor T10 shares its base in common with transistor T9. The current sources T7 and T10 are driven by the amplifiers 1 and 2 comprising PNP transistors T11, T12 and T13 T14, respectively. The two output voltages of the current switch are given by Vout(1)=alpha i(t)R(L1)/(e/Vin/Vo/+1). The differential gain is found by differentiating the differences between these two output voltages. The mai...