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