Research On CMOS Low Noise Amplifier

System on a chip (SOC) has become the main focus in the area of wireless communication. With the development of radio frequency (RF) communication and the CMOS technology, it has become a reasonable choice to implement the RF communication circuits and systems in CMOS process. As the first block of the wireless receiver following antenna, the performance of Low Noise Amplifier (LNA) greatly determines the performance of the entire system.On the other hand, while computers and communications technology are exploding, Wireless Local Area Network (WLAN) are enjoyed in personal and commercial computer field, due to that it can compensate the shortcomings of the Wire Network. To satisfy growing demands of users, WLAN are developing towards to higher frequencies, wider bandwidth and more functionality. And IEEE802.11a is one of the best wireless protocol standards, which works in the 5GHz band.Based on this band, the main researches area of the paper are as follows: Firstly, this paper introduces the research significance of CMOS RFIC, summarize the unsolved problems in CMOS RFIC designing and the researches of CMOS LNA in international papers. Secondly, it systematically introduces WLAN and the principle of the RF circuits. Thirdly, based on analyzing deeply the literature:(1) A 5.7GHz CMOS LNA which could be fully integrated is presented, and then make it small signal analyzed and noise performance analyzed in detail. To verify the circuit performance, we simulate the circuit with the ADS software. The simulation results indicates that the proposed circuit has good performance, and just includes one passive inductor, so it convenient to integrate.(2) A 5.7GHz CMOS LNA considering inter-stage matching network is presented, then analyze the inter-stage matching network's influence on the performance of the whole LNA, simulate the circuit with the ADS software. The simulation results indicates that the proposed circuit has good performance, the inter-stage matching can improve the non-matching of the common source (CS) common gate (CG) circuit due to the output impedance of CS and the input impedance of CG.(3) Based on research deeply on two nonlinear analysis methods and some common linearity improvement methods, A 5.7GHz high linear CMOS LNA is presented. Simulate the circuit with the ADS software and the results indicate that the proposed circuit has good performance. Comparing with the traditional CS-CG LNA, the circuit configuration is simple and it can improve linearity without increasing power consumption.Lastly a conclusion and prospect of this paper have been done.