The function of a Phase Shifter is to control the phase characteristics in the processing of a microwave signal. This device will convert a signal to a desired phase location via a digital command.

The theory of operation is to divide the input signal into two equal signals 90 degrees apart, I (in-phase) and Q (Quadrature). This allows the magnitude of each signal to be re-located along its vectors' axis. The two signals are then combined. Using The Pythagorean Theorem, the sum of the vectors produces the resultant output signal.

The circuit for this digital phase shifter consists of a 3 dB, 90 degree Quadrature Hybrid, two Variable Attenuators capable of a 180 degree phase shift, an In-Phase Power Combiner and drive circuits to control the variable attenuators (Click Here for Schematic).