The Design Of The Low-Noise Ampliifer For RoF System

Currently, there are a variety of wireless communications equipments, which have beenwidely used. Wireless devices must be improved because of the application of Wi-Fi, RFID andother technology. For the receiver, the most important parameters for the designer are the receivedsignal sensitivity, radiation, size, distance and noise figure (NF). In wireless communicationsystems, the low-noise amplifier，at the front of the receiver, is a key components that determinethe receiver noise figure.Low-noise amplifier is located in the front of the system. Its performance directly affects thequality of the entire system. Because the low noise amplifier is connected to the antenna, the inputand output of the LNA must be matched to 50Ohm for the maximum signal transmission. Atpresent, CMOS technology is conducive to integration and reduces the costs. The use of CMOStechnology has become the focus of the LNA. The main contributions of this paper are as follows:Firstly, we analyzed the characteristics of the MOSFET, and the relationship between thevoltage and current. The applications of the MOSFET have been shown includingcommon-source Amplifier, common-gate Amplifier and source Follower. On this basis, the noisemodel and MOSFET noise analysis have been shown. Then we explain the important role of theLNA in the system and the design parameters. The results are S11<-15dB, S22<-15dB, S21>15dB,NF<2dB.Secondly, the LNA in the recent paper in the IEEE have been analyzed in the paper. We findthe design ways of the LNA, and various design structures. The optimization method has beenshown in the paper. According to the design requirements, a narrow-band LNA has been designedin the paper by Cadence. We use 90nm IBM CMOS technology, and complete the circuitsimulation, corner analysis, DRC, LVS and post simulation. The results of the simulation are goodfor the design. A new low noise amplifier has been designed. The input and output impedancematching networks are achieved with extra variable capacitor controlled by the voltage. Thevariable capacitors used in the circuit design can make the LNA operate at some key frequencybands between 1.9GHz and 2.4GHz.Thirdly, the wide-band LNA in the recent paper has been analyzed. We comparative thedesign method of the LNA, and various design structures. The several different circuitarchitectures have been shown in the paper. According to the design requirements, a wide-bandLNA has been designed in the paper by Cadence. We use 90nm IBM CMOS technology, andcomplete the circuit simulation, corner analysis, DRC, LVS and post simulation. The results of the simulation are good for the design. We design a new circuit architecture that can improve theperformance of the noise and increase the gain of the circuit. This circuit has been verified bysimulation. The results are S11<-15dB, S22<-15dB, S21>15dB, NF<2dB, the gain and noisefigure are improved.Finally, the PCB of the IC has been tested. We analysis the results of the test circuit toimprove the experience of the circuit design.