Design of an ultra-wideband LNA using transformer matching method

A new transformer matching method for ultra-wideband (UWB) low noise amplifier is presented, which effectively extends the bandwidth and has little effect on the circuit noise. Low-frequency gain compression are realized by combining Frlan-style transformer and RC feedback loop topology in the interstage. The output matching network is composed of the Rabjohn-style transformer and LC network after Norton transformation. The power gain is enhanced by using two-stage cascode topology. The proposed UWB LNA is based on a 0.25um GaAs PHEMT process, and the post-layout simulation results show the maximum power gain of 21 dB, minimum NF of 1.6 dB in the frequency range of 4–15 GHz. The input reflection coefficient is less than -7dB. The output reflection coefficient is less than −10dB. The average output 1-dB compression point is 14dBm. The chip size is 0.82 mm.