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High Speed Analog To Digital Converter

IP.com Disclosure Number: IPCOM000093644D
Original Publication Date: 1967-Nov-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Dearden, ZT: AUTHOR

Abstract

The analog-to-digital converter operates in a voltage mode. This results in extremely quick encoding speed because the conduction path is determined before current is injected into comparator transistors, i.e., transistors on the same rung of the ladder.

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High Speed Analog To Digital Converter

The analog-to-digital converter operates in a voltage mode. This results in extremely quick encoding speed because the conduction path is determined before current is injected into comparator transistors, i.e., transistors on the same rung of the ladder.

Drawing 2 contains the encoding cores. The current path between points A- A, B-B. etc., in drawing 1 pass through the encoding cores in drawing 2. The cores can be so arranged that any common digital code can be produced at their output for the analog signal present at the input of the ladder network in drawing


1.

Transistors a and b activate the encoding ladder network. Normally the voltage at the base of transistor a is zero. Because of the base-emitter drop, the voltage thus present at the emitter of transistor b is -.8 volts. This causes the emitter-base junction of transistor b to be reverse-biased and thus prevents conduction of that transistor. When a sampling input pulse is impressed on the base of transistor a, the voltage present at the emitter of transistor b drops to -1.8 volts, thus turning transistor b on. This allows current to flow from the collector to the emitter of transistor b. In turn, current is allowed to flow through the ladder network.

The transistors in the ladder network which conduct are determined in the following manner. The input voltage e, the analog voltage to be digitally encoded, is simultaneously impressed upon the bases of transistors 1a....