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Digital - Analog Converter

IP.com Disclosure Number: IPCOM000098819D
Original Publication Date: 1959-Dec-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

French, WK: AUTHOR

Abstract

A series of gates, associated limiting resistors, an amplifier A with a gain of + 1, and a floating power supply are combined to form a circuit for simple conversion of a digital representation to an analog voltage or for concurrent conversion and subtraction involving two digital numbers.

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Digital - Analog Converter

A series of gates, associated limiting resistors, an amplifier A with a gain of + 1, and a floating power supply are combined to form a circuit for simple conversion of a digital representation to an analog voltage or for concurrent conversion and subtraction involving two digital numbers.

Precision positive and negative reference potentials are supplied from the terminal pairs + E and -E, respectively. Weighted levels of current are established through the resistors 7, 9 and 11, under control of the associated gates G1, G3 and G5, which are respectively proportional to the units, tens and hundreds positions of a positive number. Similarly, weighted levels of current are established through the resistors 8, 10 and 12, under control of the gates G2, G4 and G6, which are respectively proportional to the units, tens and hundreds positions of a negative number, or a number to be subtracted.

Simple digital to analog conversion of the number + 195, for example, is accomplished by gating on G1 for 5 units of time from line 13, G3 for 9 units of time from line 15, and G5 for one unit of time from line 17. A charge is accumulated on the capacitor C which is directly proportional to the weights of currents and the time of gating and which is the analog equivalent of the digital number.

Concurrent conversion and subtraction of two numbers may be performed. If the positive gates G1, G3 and G5 are gated on according to a particular number, such as +...