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DC Voltage Power Amplifier

IP.com Disclosure Number: IPCOM000088464D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Kallmeyer, M: AUTHOR [+2]

Abstract

This is a DC or low-frequency AC power amplifier for driving a DC motor or a similar driving means. It ensures sound proportionality between input and output for positive and negative voltages, as well as high gain and low power dissipation. Provided are a comparator which is subject to a hysteresis, a power driver, and a feedback loop from the driver output to the comparator input, with the feedback voltage corresponding to the average output value.

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DC Voltage Power Amplifier

This is a DC or low-frequency AC power amplifier for driving a DC motor or a similar driving means. It ensures sound proportionality between input and output for positive and negative voltages, as well as high gain and low power dissipation. Provided are a comparator which is subject to a hysteresis, a power driver, and a feedback loop from the driver output to the comparator input, with the feedback voltage corresponding to the average output value.

The voltage to be amplified is supplied by terminal A of comparator 1 to noninverting input 2 of differential amplifier 3. Inverting input 4 of amplifier 3 is fed with the average voltage on output 5 of power driver 6 via feedback loop 7, the average value of the output voltage being formed by low-pass filter 8.

The voltage on output 9 of comparator 1 is a function of the actual input voltage and the feedback voltage. It may assume positive or negative values because of the positive feedback by resistors R1, R2, which also determine the hysteresis voltage of comparator 1.

Oscillation occurs when the load voltage of filter 8, determined by resistors R3 and R4, exceeds the hysteresis voltage. The sampling frequency of the unloaded circuit is a function of the maximum amplitude on driver output 5, the time constant of low-pass filter 8, and the hysteresis voltage of comparator 1. It varies with the load, so that the average value on driver output 5 always corresponds to the input.

The frequenc...