A 17–32GHz Bidirectional Amplitude-Phase Control Circuit for Multibeam Phased Array Transceivers in 40-nm CMOS

This paper presents a 17–32 GHz bidirectional amplitude-phase control (Bi-APC) circuit for multibeam phased-array transceivers in 40-nm CMOS. Amplitude control is achieved using a bidirectional variable-gain amplifier (BVGA) with a 4-bit attenuator (ATT), providing wide-range, high-resolution, and low-loss amplitude tuning. Bidirectional operation in the BVGA is enabled by two symmetric three-stage amplification paths and reused broadband matching networks, while an RC-feedback (RCFB) technique in the inter-stage resonators is proposed to enhance gain flatness. Phase control is performed by a passive vector-modulation phase shifter (VMPS), where a modified Wilkinson-based combiner with C-R-C isolation and differential inductive coupling reduces area and high-frequency insertion loss. In addition, segmented control codes mitigate the quadrature imbalance of the coupler across frequency, enabling accurate wideband phase tuning. Fabricated in a 40-nm CMOS process, the 0.54-mm² core supports 17–32 GHz bidirectional 31.5-dB/360° amplitude and phase tuning range with 0.5-dB/5.625° resolution and <0.46 dB/<2.6° RMS error. It achieves 3.3/1.7 dB peak gains in receive (RX)/transmit (TX) mode, <7.3 dB NF in RX mode, >6 dBm OP1dB in TX mode, and a power consumption of 29.7 mW.