TESTING OF RF DIODE PHASE SHIFTERS

Proper operation of an RF diode digital phase shifter of the kind having a number of logic inputs to effect corresponding incremental shifts in the phase of an RF signal passing through the phase shifter, is determined by monitoring the voltages developed across resistance elements of driver stages associated with diodes of the phase shifter. Voltages developed across the diodes are monitored, while turning the driver stages on and off in certain sequences and comparing the levels of the monitored voltages with preset reference levels. The drive stages also can be tested by turning them on and off simultaneously. A fault condition is indicated when the monitored voltages deviate from preset levels.