$S$ - 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 mm
²
),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.