International Business Machines Corporation

George C Thomas

John T Trnka

Jeffrey L Lovgren

David N Moen

The digital-to-analog converter described herein generates an analog signal level from a digital value and a modulation coefficient. The converter modulates the digital word applied to the conversion stages and smoothes the resultant duty cycle modulated analog levels to produce additional analog levels between the normal levels provided by the conversion stages of the DAC. In one embodiment the duty cycle modulation of the digital value is accomplished by a rate multiplier controlling the incrementing of the digital word applied to the conversion stages. In another embodiment of the invention, the duty cycle modulation of the digital word is performed by a microcomputer. A low pass filter or a DC motor is used to smooth or filter the duty cycle modulated levels from the conversion stages.

Digital-to-analog converter

An electrical counter including a pair of counter segments connected in cascade. Each of the counter segments has a capacity of two bits and counts in Gray code of 00, 01, 11, 10 and 00 on succeeding pulses to be counted which are applied onto the segment. The second segment includes an AND circuit which is satisfied when the count of the preceding segment is 10 so as to GATE the pulse supplied at that time on to the second segment so that the second segment has its value changed at the same time as the first segment has its value changed from 10 to 00.

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Rochester, MN, United States of America

George C Thomas