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

A capacitor cross-coupled (CCC) wideband commongate 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 highfrequency 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-μm 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 × 0.26 mm².

I. Introduction

Wideband multistandard receivers have been investigated widely for their capability of demodulating different radio signals at a time. Low-noise amplifier (LNA) is a key component in the receiver front end. For a wideband receiver, several narrowband LNAs can be adopted to accommodate the frequency bands of each standard. However, this architecture will have prohibitively large size and high cost. It also increases the complexity for designing such a system. Therefore, a wideband LNA is more suitable for a wideband receiver [1].