A multi-band low noise amplifier with wide-band interference rejection improvement

In this paper, a differential multi-band CMOS low noise amplifier (LNA), operated in a range of 800–1700 MHz, is proposed. In this design, the LNA is integrated wide-band interference rejection (input band selection technology) and capacitive cross-coupling topologies, which can improve the interference rejection and noise figure preference. Moreover, the conventional notch filter technology only rejected the specified frequency. In this experiment, by using the proposed wide-band interference rejection technology, the LNA can reject unwanted signals (out-of-band signals) and image signals from different frequency. Thus, the LNA has good linearity and interference rejection performance. With the increasing use of frequency spectrum, the proposed technology is even more important. The post-simulation results of proposed LNA show that the voltage gain is 13–17.5 dB, the noise figure (NF) is less than 3.4 dB, and the third-order intercept point (IIP3) is 7.36 dBm. The LNA consumes 8.96 mW under 1.8 V supply voltage in TSMC 0.18-μm RF CMOS process.