A switchable dual‐mode fully‐differential common‐source low‐noise amplifier in 0.18‐μm CMOS technology

Abstract

A highly‐integrated switchable dual‐mode low‐noise amplifier (LNA) is proposed and implemented in standard 0.18 μm complementary metal‐oxide‐semiconductor (CMOS) technology for ultra‐high frequency‐radio‐frequency identification (UHF RFID) reader receivers. This dual‐mode LNA can be controlled to operate in two different modes in order to meet the requirements for the listen‐before‐talk mode and the normal mode of the UHF RFID reader receiver, respectively. The fully‐differential common‐source cascode topology with perfect input impedance matching, capacitive cross‐coupling, and common‐mode feedback techniques are employed to improve its performance. Measurement results show that, from a single power supply of 1.8 V, the LNA achieved the power gain (S21) of 9.1 dB, the input power reflection (S11) of −20 dB, the minimum noise figure (NF) of 3.6 dB, and the P1dB of −5 dBm in high‐gain mode. In high‐linearity mode, S21 of 3.2 dB, S11 of −17 dB, NF of 5.2 dB, and P1dB of −1.3 dBm were obtained.