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Sinewave Amplitude Control

IP.com Disclosure Number: IPCOM000049949D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Roalson, HJ: AUTHOR

Abstract

A circuit is shown which generates a sinusoidal waveform electronically with a precise relationship between a level-setting voltage and the sinewave amplitude.

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Sinewave Amplitude Control

A circuit is shown which generates a sinusoidal waveform electronically with a precise relationship between a level-setting voltage and the sinewave amplitude.

The circuit comprises an operational amplifier 10 to which is coupled the level setting voltage as one input and a second input from detector 12. The detector 12 can be either a peak to peak rectifier/ filter or, if the average DC level of the output sinewave is known accurately, it can be a simple peak detector. An active filter 14 is designed for the range of frequencies used with a gain appropriate for the signal levels of the circuitry. The exact gain of the filter is not critical since the input is automatically adjusted to achieve the correct level. The amplifier 16 following the active filter may be a power amplifier, if necessary, to drive the load. The gate circuit 18 can be almost any logic buffer with an open collector output. The level set voltage can be applied directly to operation amplifier 10 or, alternatively, can be applied as a group of level set bits to digital to analog converter (DAC) 20 should the application require a digital input.

One application for the circuit is to use the sinewave output at terminal 22 to control the drive level to a motor. In this application, the level set voltage is selected from two reference voltages - one for acceleration, the other for full- speed running. The detector senses the peak-peak, power amplifier output during accele...