A CMOS 24-30-GHz Low-Phase-Variation Variable Gain Amplifier Design for 5G New Radio

This letter presents a 24-30-GHz variable gain amplifier (VGA) achieving low-phase variation in a standard RF 65-nm CMOS process. The proposed VGA employs two stages. Phase compensation during the gain variation is realized with the dynamic complementary phase variation at the first stage. The second stage is utilized to increase the gain and keep linearity. Measurement results prove that the proposed VGA achieves a continuous gain tuning range of 8.3 dB. Under this condition, low-phase variation is realized with the root-mean-square (RMS) phase error less than 3° from 24 to 30 GHz. Moreover, the RMS phase error is less than 2° at the desired 5G frequency band from 27.5 to 29.5 GHz. The peak gain is measured with 18.7 dB at 29 GHz. With the max gain setting, the measured OP 1dB and OIP 3 are 5.1 and 9.3 dBm, respectively, and the measured noise figure is from 4.6 to 6.8 dB at the frequency range from 24 to 30 GHz.