A wide band Sanky phase shifter for phase sensitive detectors.

In this paper the design details of a wide band Sanky phase shifter have been given. This phase shifter can be used with phase-sensitive detectors which are required to work with variable reference frequencies. The phase shifter uses its own built-in oscillator that provides the reference frequency.
A phase-shifting network is essential in phase-sensitive detectors to compensate for the phase shifts occurring in an amplifier system. This network, which is normally used in the reference channel, often comprises R-C networks. The input and output of such networks are both sinusoidal. With such networks the 'control' cannot be calibrated, as the phase shift introduced for a certain amount of the 'control' movement is frequency dependent. Since, in switching-mode-operated phase-sensitive detectors, the reference is a train of square waves, a modified version of the Sanky phase shifter (Sankaranarayanan 1973) can be used to introduce necessary phase shifts and the 'control' can be straight away calibrated independent of frequency as described in this paper. Although, De Sa and Molynenx (1964) and Adby (1968) have suggested two different techniques for this purpose, the modified Sanky phase shifter becomes very handy and elegant to get the phase shifted. However, in this case, instead of using the normally available L-C or R-C type of oscillator to provide the sinusoidal wave train for excitation, an oscillator that gives a sinusoidal wave generated from a triangular wave has to be used. This is due to the fact that it is essential to have a constant amplitude triangular wave independent of frequency for phase shifting in the Sanky phase shifter. In this paper the design details of a wide band Sanky phase shifter have been given. This phase shifter can be used with phase-sensitive detectors which are required to work with variable reference frequencies. The phase shifter uses its own built-in oscillator that provides the reference frequency.
A... [ABSTRACT FROM AUTHOR]