A 38–96 GHz Bi-Phase Amplitude Modulator With 2.9 dB Insertion Loss Using Deep-Saturated HBTs

Low-power modulator circuits are essential in energy-efficient mm-wave transceiver frontend circuits, yet the associated high RF losses require additional power consuming buffer stages. In this paper, a wideband and low-loss balanced bi-phase amplitude modulator topology is presented based on the Gilbert-core; however, the transconductance stage is removed and the switching quad transistors are operated in the deepsaturated region with zero collector-emitter voltage consuming 0.3mW. The control over the amplitude is obtained with a biasing circuit based on Schottky diodes. The proposed modulator is realized in an advanced SiGe BiCMOS technology and achieves an insertion loss of only 2.9 dB at 60 GHz. From 30 GHz to the measurement limit of 62 GHz, BPSK modulation with a data rate of 0.5 Gb/s is supported with 32 dB of measured EVM, demonstrating promising performance for future integrated sensing and communication applications. Other key parameters, including
58 GHz of 3 dB bandwidth and 48 dB of on-off isolation, showcase the excellent performance compared to the results in literature.