Design Of A PHEMT Wideband Low Noise Amplifier In UHF Band

Recently, with the rapid development of mobile communications, the higher and higher requirements are raised to the wireless receiver. Low Noise Amplifier(LNA) as one of important blocks in front-end-module, decides the specifications of receiver, such as sensitivity, dynamic range.In the practical application, when the antenna receives a signal with a large order of magnitude, the receiver would be unable to work properly, because the circuit module at the end of the mixer is saturated when input signal is amplified by LNA Therefore, we designawideband LNA with by-pass switch function. When receiving a weak signal, LNA work properly, but when the input signal is too strong,throughby-pass switch, signal directly transmits to the back end circuit.In this thesis, the main jobs completed are includedFirstly, analyzing the basic design theory of preceding stage wideband LNA, and backward stage by-pass switch.Followed by the completion of the schematic diagram of the LNA simulation, and layout design.Finally, after production process, to debug and package the chip.According to the actual measured results, from 400～700MHz, the chip can reach blew-lOdB the input return loss, NF can keepamong 0.85dB-1.05dB, the linear gainabove 18dB, the input third order intercept point isabove OdBm, the by-pass switch insertion loss keeps among -1.1dB～ -0.99dB, and the current consumption keeps 10mA. The measured results demonstrate that the chip can meet the requirements for receiver system, and some important parameters of the chip over existing commercial RF front-end LNA products.