New approaches for designing minimum loss wide phase range digital phase shifters

Four different circuit configurations are proposed to design 0 degrees -360 degrees wide range, low loss, loss balanced phase shifters. Each configuration utilizes 3 p-i-n diodes. As a consequence of this work, 180 degree phase shifting cells for multibit phase array antenna systems using 3 p-i-n diodes can be constructed in a straightforward manner. Operation of the new circuits is based upon the phase shifting properties of symmetric low/highpass 3 element LC ladders. Assuming the utilization of lossless p-i-n diodes and ideal reactive elements, explicit design equations are presented. A numerical method, which includes the diode losses as well as component parasitics, is also described to design practical phase shifters with minimum balanced loss at a given operating frequency. Examples are included to exhibit the use of explicit design formulas, and computer simulations are performed to analyze the loss and phase characteristics of the new circuits. It is expected that new configurations will find application in the commercial and especially military large array antenna systems over the EHF band to be implemented as monolithic microwave integrated circuits (MMIC).