A 0.384mm² Ka-Band 4-Bit True Time Delay Phase-Shifter Using BiCMOS Integrated Phase Change Material Switches

This paper describes a BiCMOS integrated phase shifter using Phase Change Material switches. A 28 GHz, 4-bit 0–321° phase shifter is presented. The complete circuit occupies only 0.384 mm², including 16 PCM switches, and 4 microstrip delay lines. Two versions of the circuit have been built, one using identical switches, another one using different switch geometries to balance the phase shifter loss. On an amplitude balanced version, the measured losses are between 7.4 and 8.5 dB, leading to a figure of merit of 43.4° per dB.