Study Of Wireless Communication RF Front-end Circuits And Mixed-integrated Receiver

The wireless communication systems, such as cordless, GPS, and Bluetooth applications, etc, have increased the demand for low-cost and high performance front-end receivers. The need for low voltage operating RF chips with low power dissipation and high performance are increasing rapidly. The system components, such as noise, gain, linearity, maximum power transmission and other factors must be considered in the design of RFIC, in addition to the required of power consumption, speed of digital IC. At the same time, under the drastic market competition, telecommunication system with low cost, low power dissipation and multifunction become the development trend of radio frequency integrated circuits. The LNA and Mixer are the important components of a typical frond-end circuit, which directly determine the receiver sensitivity and dynamic range. So, improving the performance of LNA and MIXER becomes a popular issue. This thesis explores design techniques for low noise amplifier and mixer by focusing on noise optimization and linearity improvement.Firstly, the thesis gives analysis about the common conception of RF design, such as S-parameter, two port network, gain, noise, linearity, etc. Then it summarizes the universal structures of input impedance matching, sources of MOSFET non-linearity and linearization technologies for low noise amplifier .A new linearization method is then proposed for linearizing the traditional structure of cascode LNA, and the linearity is improved by a 3rd intermodulation distortion sinker which comprised of two MOS FET. Compared with traditional structure, proposed circuits have an IIP3 improvement of 15dB, current dissipation of a 1.8mA increase and noise figure of about 0.2dB increase.Secondly, the thesis introduces the basic theory of mixer and sums up boosting techniques for gain, noise and linearity performances. The thesis also offers modifications to the Gilbert double-balanced mixer by adopting method of current injection, the simulation results show that the modified Gilbert mixer has achieved a conversion gain of 17.4 dB, NF of 8.8dB. Then based on the current bleeding mixer, a tuning inductor is used to improve the conversion gain and noise figure of mixer, and a certain improvement of linearity is also obtained. Compared with the conventional current bleeding mixer, when the LO power is -3dBm, the improved Gilbert mixer has the gain increase of 1.76 dB, IIP3 increase of 2.1dBm, NF decrease of 1dB.Designs in this thesis are based on SMIC 0.18μm RF CMOS technology.A UHF band receiver is designed in chapter 6, using mixed-integrated method. Test results show that: under 12dB SNR conditions, the sensitivity reaches to -115dbm, local oscillator and image rejection has been promising to meet the design requirements.Lastly, chapter 7 summarizes the above design work.