A High-Linearity Wideband Common-Gate LNA With a Differential Active Inductor

Abstract

A capacitor cross-coupled (CCC) wideband common-gate low-noise amplifier (CGLNA) with improved linearity and frequency response is presented. A novel differential active inductor (AI) is designed to improve the in-band gain flatness and high-frequency gain using the gate-inductive gain-peaking technique. The AI prevents the small-signal current flowing to the ground through the gate–drain capacitors. The CCC technique improves noise performance and saves power. However, it will also increase nonlinear distortions due to the boosted signal amplitude. To overcome the CCC-induced linearity deterioration, the derivative superposition technique is employed by using two parallel input transistors biased at different regions. The measurement results of the fabricated prototype in a 0.18- $\mu\text{m}$ CMOS process show that the voltage gain, the minimum noise figure, and the third-order intercept point are 16.9 dB, 2.5 dB, and 5.5 dBm, respectively, within the 3-dB bandwidth from 100 MHz to 1.45 GHz. The CGLNA consumes 9.3 mW from a 1.8-V supply and the active area is $0.29\times 0.26 \text{mm}^{2}$ .