Multiphase sine-shaper circuit

This paper describes a method of generating multiple sine waves of the same frequency but at different phases. The circuit, relying upon bipolar transistors, is compact and easily produces several phases. The amplitude and the frequency of the sine waves can vary while keeping the phase angle between the different waves constant. A four phase circuit was built on a linear integrated circuit array using bipolar transistors. A similar circuit, also built on the same array, provided temperature compensation. The integrated circuit provided three sine waves to control an induction motor. The phase differences between the three output phases were less than one degree, and amplitude differences were within two percent.