A Frequency-Reconfigurable Dual-Band Variable-Gain Phase Shifter for 5G mm-Wave Beamforming

This paper presents a frequency-reconfigurable dual-band phase shifter operating in the n257 (26.5–29.5 GHz) and n260 (37–40 GHz) bands for fifth-generation (5G) communication. The proposed phase shifter is based on an active vector-summing architecture and provides simultaneous gain and phase control for beamforming applications. To support dual-band operation with a large frequency separation, a reconfigurable RC–RL polyphase filter (PPF) is employed for in-phase/quadrature (I/Q) signal generation. The proposed PPF reconfigures its inductance and capacitance according to the operating band, reducing insertion loss and minimizing I/Q phase error in both frequency bands. Gain and phase are controlled by digital-to-analog converter (DAC)-assisted vector summation with 4-bit gain and 6-bit phase control resolution, while a reconfigurable output matching network provides optimized impedance matching in each operating mode. The phase shifter is implemented in a 28 nm fully depleted silicon-on-insulator (FDSOI) process with a core area of 0.26 mm2. The measured RMS phase errors are <1.18° and <1.5°, and the RMS gain errors are <0.26 dB and <0.35 dB in the n257 and n260 bands, respectively. The measured DC power consumption is 11 mW and 15.4 mW in the n257 and n260 bands, respectively.