Continuous Varactor-Diode Phase Shifter with Optimized Frequency Response

A method is introduced for designing continuous varactor-diode phase shifters with optimum frequency response. The circuit used gives very small frequency variations of the phase shift if the maximum phase shift of the device is less than about 200°. Measurement results on a 180° L-band phase shifter are presented. This unit gives less than 5° variation of any given phase shift less than 180°, when the frequency is changed from 1.5 to 1.7 GHz.