$S$ - and $C$ -Band Ultra-Compact Phase Shifters Based on All-Pass Networks

Ultra-compact phase shifters are presented. The proposed phase-shifting circuits utilize the lumped element all-pass networks. The transition frequency of the all-pass network, which determines the size of the circuit, is set to be much higher than the operating frequency. This results in a significantly small chip size of the phase shifter. To verify this methodology, 5-bit phase shifters have been fabricated in the S - and C -band. The S -band phase shifter, with a chip size of 1.87 mm ?? 0.87 mm (1.63 mm²),has achieved an insertion loss of 6.1 dB ??0.6 dB and rms phase-shift error of less than 2.8^?? in 10% bandwidth. The C -band phase shifter, with a chip size of 1.72 mm ?? 0.81 mm (1.37 mm ²), has demonstrated an insertion loss of 5.7 dB ?? 0.8 dB and rms phase-shift error of less than 2.3^?? in 10% bandwidth.