Phase control of pulsed broadband microwave amplifiers

A phase shifter for pulsed broadband amplifiers is described. The phases of the input and output signals are compared in a polar discriminator, and an error signal is derived which steers a voltage-controlled phase shifter at the amplifier input. Applications are for smoothing out within-pulse and pulse-to-pulse phase shift in amplifiers and for providing a relatively accurate phase shifter for active phased arrays using amplifiers. A four-bit phase shifter has been built and measured in the 3-3.5 GHz band. The paper reports steady-state and transient performance.