A DC-10.5-GHz CMOS Distributed Amplifier with 3.2±0.3 dB NF, 10.5±1.4 dB Gain and ±13.8 ps Group Delay Variation

A DC-10.5-GHz CMOS distributed amplifier (DA) with flat and low noise figure (NF), flat and high power gain (S₂₁), and small group delay variation using standard 0.18 μm CMOS technology is demonstrated. Flat and low NF was achieved by adopting the proposed RLC terminal network with 140 Ω terminal resistance at dc and very high frequencies (instead of the traditional 50 Ω terminal resistance or the recently proposed RL terminal network) for the gate transmission line, and a slightly under-damped Q-factor for the second-order NF frequency response. Besides, flat and high S₂₁ was achieved by using cascoded transistors as the gain cell. Over the DC-10.5-GHz band, the DA consumed 29.16 mW and achieved flat and high S₂₁ of 10.5±1.4 dB, flat and low NF of 3.2±0.3 dB, and excellent phase linearity (the group delay variation was only ±13.8 ps), one of the best NF and phase linearity results ever reported for a CMOS DA or wideband LNA with bandwidth greater 7.5 GHz.