A <i>S</i>-/<i>C</i>-Band 6-bit Passive Phase Shifter With an X-Shape Merged 180° and 90° Cell

This letter presents a 6-bit passive phase shifter (PS) for 3.7–5.3-GHz (S-/C-Band) phase-array communications. The PS adopts several cascaded switchable phase-shifting cells, in topologies of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Pi $ </tex-math></inline-formula>-type, T-type, and the proposed X-shape structure. The 180° and 90° phase-shifting cells are merged and co-designed, whose switch configuration resembles the X-shape. It allows the reduction of one switch transistor and its associated insertion losses in the RF path. The proposed 6-bit PS is designed and fabricated in a 55-nm bulk CMOS. The measured results reveal an insertion loss (IL) of 8.5–9.5 dB, a root-mean-square (rms) phase error of 3.50°–5.15°, and an rms amplitude error of 0.23–0.51 dB. The chip occupies an area of 0.80 mm2 and consumes negligible power.