A $Ka$ -Band Variable-Gain Amplifier With Low OP1dB Variation for 5G Applications

This letter presents a Ka-band variable-gain amplifier (VGA) with low output 1-dB compression point (OP1dB) variation for 5G applications. The VGA comprises a cascode current-steering amplifier and a common source amplifier with capacitance neutralization and uses dual current steering to maintain a constant OP1dB. Implemented in a 65-nm CMOS technology, the proposed VGA consumes 8 mW and occupies a core chip area of 0.34 mm ×0.49 mm. The proposed VGA achieves a power gain of 21.2 dB at 27.5 GHz and a 3-dB bandwidth of 25.75-29.25 GHz. With the dual current-steering technique, the OP1dB of the fabricated VGA was measured as -1.4 to -0.2 dBm at 27-29 GHz for all gain states.