A 2.76 mW, 3–10 GHz ultra-wideband LNA using 0.18 µm CMOS technology

A low-power (2.76 mW) common-gate (CG) low-noise amplifier (LNA) for ultra-wideband (UWB) systems using standard 0.18 μm CMOS technology is demonstrated. Instead of the traditional single parallel inductor (L_S1 only), we propose a new matching network consisting of a series L_S1-R_S1 in series with a parallel L_S2-RS₂ to enhance the input matching bandwidth. Flat and high S₂₁ was achieved by using the connecting inductor L_C and the peaking inductor L_D2 to compensate the gain loss at medium-frequency and high-frequency, respectively. In addition, for suitable values of L_C and L_D2, flat and low NF (i.e. a nearly critically-damped Q-factor for the second-order NF frequency response) can also be achieved. Over the 3-10 GHz band of interest, the LNA achieved S₂₁ of 10.1±1.7 dB, minimum NF of 3.9 dB (at 4 GHz) and an average NF of 4.6 dB. The power dissipation was 2.76 mW, and the corresponding figure-of-merit (FOM) was 4.3. Both are of the best results ever reported for a CMOS UWB LNA.