Abstract: A typical alternating current two phase servomotor has two windings displaced 90.degree.; these windings are normally identified as the reference winding and the control winding. Rotational direction and speed of the motor may be controlled by applying AC voltages of the proper waveform amplitude and phase relationship to these windings. When controlling the direction of rotation and speed of such alternating current servomotors in accordance with a DC error signal, pulse width modulation is utilized. The DC error signal is compared with a periodic varying function and its inverse to generate a series of pulses that are logically combined with a square wave and its complement during an enable period to generate a first and second series of pulses each having a width related to the magnitude of the error signal and coupled to energize the control winding of the alternating current servomotor. Similarly, a second periodic signal and its inverse are used to generate pulses for the reference winding.