Ultrawideband CMOS VGA With 2.23 dB NFmin Using Coupled-ML Neutralization

This study reports a low power-dissipation (PD) and low noise-figure (NF) ultrawideband CMOS variable-gain amplifier (VGA). The VGA uses coupled microstrip-line (CML) neutralization, body-floating of transistor M1, and multiple inductive compensations, featuring complementary common-source (CCS) input and common-source (CS) output stages to achieve low PD and NF values and a wide bandwidth (BW). Gain flatness in the ultrawideband VGA is achieved by fitting the coupling between the CML (with the electrical length of a compensated gain-flatness inductor CL). The VGA with a PD of 5.85 mW achieves excellent S21 BW of 32.3 GHz (2.9–35.2 GHz), maximum S21 of 11.9 dB, minimum NF of 2.43 dB, and average NF of 4.11 dB for 5G FR2 and 6G FR3. The input 1-dB compression point of the VGA is −11.5 dBm. Moreover, the VGA with a chip area of 0.356 mm2 attains a decent gain tuning range of 20 dB (−3.8 to 16.2 dB) under 1.35 dB/step for 5G NR band N257.