A Design Of X-band Mmic Low Noise Amplifier

Wireless communication technology is widely applied in many fields, which is closely connected with people’s daily life. The high-performance microwave integrated circuits are in great demand among not only individuals but also the whole country. This paper focuses on the design and realization of the X-band low noise amplifier(LNA), including MMIC technology’s background, parameters, modelling of the device and process analysis. At last, this paper elaborates the design process of the low noise amplifier in detail.The 0.15 μm GaAs Low Noise pHEMT process line provided by Taiwan WIN Semiconductor Company is adopted in this paper for designing a low noise amplifier, working from 8 to 12 GHz. At the same time, a structure with three cascaded circuits is used in this design. The source side feedback technology and the attenuation circuit are adopted to improve the stability of the first stage amplifier. Since this stage contributes the most to the system, the design is mainly aimed at low noise, matching the input which uses the minimum noise coefficient. Due to the not-high-enough gain, the second stage amplifier is also mainly aimed at the noise matching. The gain of the amplifier decreases with the increase of the frequency, and almost no effect is made by the third stage circuit. In this case, negative feedback structure is used to compensate for gain, improving the gain flatness of the system. Input and output ports are both matched to 50 ohm as required, which makes it easily to connect with other stages. Then the optimization of the three-stage cascade circuits proceed. At last, the layout schematic and the Momentum electromagnetic simulation will be debugged several times to obtain a good parameter.The testing results of X-band MMIC low noise amplifier performs well within the working band. The noise figure is less than 1.2dB, and the gain is more than 20 dB. The flatness of gain is less than ±1.5dB, and input/output voltage standing wave ratio is less than 2.0. All the expected design goals are perfectly met.