The servo circuit controls the amplitude of the sine wave

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The servo circuit controls the amplitude of the sine wave [Copy link]

The figure is a schematic diagram of the servo system with oscillator amplitude control. This circuit forms a closed loop system that provides an AC signal with a fixed and adjustable peak-to-peak amplitude centered around 0 V. Figure: In the servo system with oscillator amplitude control, the servo signal forces the peak amplitude of the AD633 output to match the DC reference voltage provided by the user on the error integrator.A 1kHz sine wave labeled AC_INPUT is AC coupled to the AD633 multiplier chip and AC_INPUT is multiplied by the servo signal. The output of the multiplier is equal to a scaled version of AC_INPUT. This 1V sinusoidal output signal is fed back to a peak detector and the peak value of the signal is compared to a user supplied reference voltage. The error integrator integrates the difference between the peak and reference values and produces the servo signal that is fed to the multiplier. The signal forces the peak amplitude of the AD633 output to match the user supplied DC reference voltage on the error integrator. The AC coupling of the input signal and the frequency of the input signal are not fixed requirements. The circuit was successfully tested using a 1kHz sine wave with an amplitude of 4.5V as input and produced a 1V sine wave output with a set point reference voltage of 1V. By Darren O'Connor