Variable-Phase All-Pass Network Synthesis and Its Application to a 14–54 GHz Multiband Continuous-Tune Phase Shifter in Silicon

This article presents a novel synthesis procedure to implement variable-phase all-pass networks (VP-APNs). The synthesis procedure is based on linear-phase all-pass transfer functions, enabling implementation at millimeter waves. Using the proposed synthesis, VP-APNs with analog and digital control are implemented for the first time in silicon. Using 0.25-μm BiCMOS, the VP-APNs are manufactured and measured, validating the synthesis procedure. Finally, the validated VP-APNs are combined to realize a phase shifter. By combining the analog and digitally controlled networks, we obtain a continuous-tune phase shifter with multiband capabilities, successfully covering several bands from 14 to 54 GHz. This includes Ku-, K-, Ka-, and V-band, as well as both 5G bands around 28 and 39 GHz.