A Compact Switchless Bidirectional Variable Gain Amplifier for IF Distribution in 6G Phased Arrays in a 130-nm BiCMOS Technology

This paper presents a compact and bidirectional variable gain amplifier (VGA) for compensation of interconnection losses for modular system approaches, and a version with integrated Wilkinson power divider for the distribution of data signals at an intermediate frequency (IF) in sub-THz phased arrays. The gain of the VGA can be set from -20 to 13.7dB giving it a large gain variation of 33.7dB, while the gain of the power divider variant is 3.3dB lower. The VGA achieves a 3-dB bandwidth of 27-38.7GHz, with the power divider the 3-dB bandwidth changes to 25.7-37.7GHz. It provides high linearity with an output referred 1-dB compression point of 7.2dBm for the VGA and 1.2/7.4dBm for the active power divider, depending on direction. The bidirectional operation is achieved by changing the gain settings of the two VGAs instead of RF switches or switching off the power supply, which allows for high switching speeds between directions.