Design Of A Low Noise Amplifier And A Down-conversion Mixer In A 2.5GHz Radio Frequency Receiver

With the quick development of wireless communications, radio frequency integrated circuits (RFIC) as core devices of wireless transmission systems are being widely used in mobile communications, satellite navigations, digital TV, etc., and their trend is towards to high performance, high integration, low power and low cost. Presently more and more RFICs are fabricated in SiGe BiCMOS process, which have nice performance at high frequency, and have high integration, and have low cost.Low noise amplifiers (LNA) and mixers are the pivotal modules of a wireless receiver, which affect sensitivity and dynamic range of the receiver. This thesis analyses transistor noise performance using noisy two-port network theory, and shows the way of optimizing LNA's noise performance, and analyses sources of LNA's nonlinearity. It also analyses the linearity of mixers, and gives the methods of optimizing mixer's linearity. On the base of theory analysis, a LNA and a mixer of a receiver chip used in compass navigation satellite system have been designed. The LNA uses differential structure, and its gain can be tuned. The mixer uses the structure of Gilbert, and uses current injection technology to improve conversion gain and decrease LO amplitude. In the end, the circuit is laid out, and a whole layout is shown.The process of 0.35μm SiGe BiCMOS is used to produce the circuit, and a test to the chip is carried out. The result shows that voltage gain of high gain mode and low gain mode is 30dB and 12.2dB respectively, and the input reflection coefficient is -14dB. The noise figure of cascade system is 2.5dB (high gain mode) and 6.5dB (low gain mode), and input 1dB impression point is -26dBm (high gain mode) and -15.8dBm (low gain mode). The supply voltage of the whole circuit is 3.3V, and current consumption is 19mA.