A Low-Loss Compact 60-GHz Phase Shifter in 65-nm CMOS

This paper presents a 60-GHz low-loss compact 4-b phase shifter in a 65-nm CMOS. It is based on a 1-b high-pass/low-pass structure and a 3-b switched-filter structure, and employs fully custom-designed capacitors with a high quality factor for low insertion loss. The phase shifter with custom-designed capacitors reduces an insertion loss by 2.6 dB at 60 GHz. The average insertion loss is 8.1 dB at 60 GHz, and the return loss is better than 10.6 dB over a range of 57-66 GHz. The measured 16-output state of the fabricated phase shifter has a phase resolution of 22.5° with an rms phase error less than 5.5° over the 57-66 GHz range. The fabricated phase shifter has a compact core size of 0.42 mm × 0.22 mm. To the best of our knowledge, this phase shifter achieves the lowest insertion loss and the smallest core area of all the published 60-GHz 360° -coverage passive CMOS phase shifters.