A CMOS LNA With Noise Cancellation For UWB Receivers

With the rapid development of the communication technique and the growing demand of the markets, better performance of radio-frequency (RF) wireless receivers is requested to achieve higher data transfer rate, lower cost, less power consumption. In this circumstance, ultra-wideband (UWB) technology has caught people's attention, and is regarded as one of the key technologies of next-generation communication. As first stage of the receiver, Low Noise Amplifier (LNA) directly affects the receiver's performance. Therefore it carries most importance to research LNA.Low-noise amplifier (LNA) is one of the key circuits of the wireless transceiver front-end. As the first level of the whole circuit system, its gain, noise, linearity, etc, those parameters affect the whole circuit system performance strongly. Meanwhile, in order to meet the high reliability low cost and highly integrated circuit requirements, the RF transceiver need to be able to be integrated on one chip.In order to design a good performance and new structure LNA, the paper covered the following aspects:(1) Firstly, it gives a brief introduction on the on-chip inductance capacitors in CMOS process and the on-chip transformers. The two-port network and the cascade system noise are analyzed and formula of them are given. Then it introduces the basic principles and structure of LNA, a newly emerging topology—the noise canceling technology. The advantages and disadvantages of these types of structures are described and compared.(2)Because noise canceling technology is only applied to narrow-band LNA, a common gate (CG) amplifier is often with high bandwidth but also high noise figure. In terms of this limitation, this paper present a structure that uses the CG amplifier as the LNA input stage, and the noise cancellation technology is applied at the back to cancel the input stage noise at the output stage. It gives structure of cascade topology which combines CG amplifier and noise canceling technology and it effectively widen the with a lower noise figure.(3) For deficiencies that the gain of the noise canceling structure is too low, it suggests a way of using broadband improved current reuse technology, and combining on-chip transformers to improve the gain of noise canceling structure to give it wide bandwidth, high-gain, and low noise figure.Finally, the LNA is designed in TSMC 0.18μm RF CMOS process, and the ADS simulation results show that, it works in 3.1-10.6GHz, in the output impedance matching S₁₁&S₂₂<-11 dB. The gain is 15.1dB and the noise figure NF is 3.9-5.8dB.