Research And Design Of Low Noise Amplifier In The Bluetooth System

The main work of this dissertation is to research and design a Low Noise Amplifier in Bluetooth SoC using TSMC 0.18um Mixed-Signal CMOS technology.The sensitivity of communications systems is limited by noise For a Bluetooth SoC chip, LNA is the first stage in receive path, whose main function is to provide enough gain to overcome the noise of subsequent stages (such as mixer) and introduce a minimum amount of noise to the signal, This LNA should accommodate large signals without distortion, and must present a specific impedance (50ohm), to the input source.Firstly the architecture of the Bluetooth RF front-end is introduced, and makes an overview on most blocks of this architecture, especially the LNA.Low noise is very important to the performance of LNA. Secondly, the electrical noise and the noise in communication systems is discussed, especially the thermal noise in MOSFETs, the relationship between the noise figure of LNA and overall noise figure of a cascade systems. LNA dominate the overall noise figure of the receive path is proved.Another important work of this dissertation is the design of an RF low-noise amplifier integrated with a CMOS Bluetooth SoC chip. Base on the spec of Bluetooth receiver, an variable gain LNA is realized by control the current flow in the load of LNA. A new high quality switch cap circuit which used to tune the resonant frequency of LNA is introduced. To decrease the noise figure, a Gm-boost architecture is used in LNA design. Design methodology is discussed from the aspects of noise figure, impedance match, forward voltage gain and linearity and some experience in layout design and parasitic extraction is discussed.The test methodology and test result is analyzed in the forth part of the dissertation. The test result is similar to simulation result.In the end of this dissertation, summary of previous work and suggestion for future work are given.