A Low-Loss Continuously Tunable Phase Shifter Based on a Bandpass Filter with Reconfigurable Transmission Zeros
A new class of phase shifter based on a bandpass filter with reconfigurable transmission zeros is presented in this work. By using tunable resonators that are extracted from the main signal path, a transmission phase shift is obtained with minimal effect on the insertion loss from the tuning elements. A total phase range of 120 degrees is measured with a maximum figure of merit of 80 degrees/dB. A study using the coupling matrix forms the basis of the phase shifter and the measurements and simulations agree well with the theory. Additional phase range can be obtained by adding additional transmission zeros without impacting the insertion loss.