120‐GHz 2‐bit reflection‐type phase shifter based on PIN diodes switched‐lines

Abstract

Abstract In this paper, a 2‐bit digital reflection‐type phase shifter (RTPS) working at 120 GHz is presented. It uses a compact coupled‐lines coupler with low insertion loss and high isolation over a wide bandwidth. The loads are made by a microstrip‐line loaded by three PN jonction separated by an intermediate region I (PIN) diodes whose states are tuned ON/OFF to obtain 90°, 180° and 270° phase shift relative to the reference (0°). Measurement results show root mean square (RMS) phase and amplitude error equal to 10.3° and 1.2 dB, respectively. The maximum insertion loss is equal to 8.6 dB, leading to a figure of merit of 31°/dB. As shown by simulation, by flipping PIN diodes and using negative voltage for biasing, the maximum insertion loss could be reduced to 3.6 dB (figure of merit of 75°/dB) along with a great improvement in RMS phase and amplitude errors, thus showing the potential of the proposed architecture.

Keywords

• BiCMOS integrated circuits
• coupled transmission lines
• millimetre‐wave phase shifters
• p–i–n diodes