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Current Switch for Dot Decoder

IP.com Disclosure Number: IPCOM000092767D
Original Publication Date: 1967-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Garrett, MJ: AUTHOR [+2]

Abstract

The circuit comprises a current switch with multiemitter output transistors for driving a dot decoder. The circuit provides high-speed driving of low-impedance decoder output lines P...W.

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Current Switch for Dot Decoder

The circuit comprises a current switch with multiemitter output transistors for driving a dot decoder. The circuit provides high-speed driving of low-impedance decoder output lines P...W.

Each current switch 1, 2, and 3 of drawing 2 is as shown in drawing 1. Transistors T1 and T2 are the current switch pair, only one of which conducts at a time depending on whether input signal A is below or above ground potential. Transistors T3 and T4 are controlled by T1 and T2 and provide emitter-follower control for multiemitter transistors T5 and T6. Outputs 1...4 are in antiphase with signal A. Emitter outputs 5...8 are in phase with A. Transistor T7 conducts continuously and maintains the voltage of line 10 constant at constant temperature. T7 changes the voltage of line 10 with variations in temperature so that the positive levels of outputs 1...8 remain constant.

The dot decoder of drawing 2 has terminations as shown for the line P. W is negative. The remainder are positive. The circuit is such that no transistor reaches saturation. The current switch of drawing 1, or the entire circuit of drawing 2, can be constructed in integrated form.

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