Direct Synthesis of Passband Non-uniform Transmission Lined Matching Sections with Discontinuities at the Ends and its Application in Broadband Amplifier Design

This paper presents an application of non-uniform transmission lines (NTL) as the matching networks in broadband amplifier which are modeled using the first order nonlinear differential equation and based on an analytical technique under the WKB approximation. In this example, we observed that the input complex impedance is more difficult to be matched to 50 Ω in the operating band with general lumped networks or transmission-line stubs, so we used a non-uniform transmission line to achieve the passband matching network. As the measurement results, return loss is better than 10 dB for the operating frequency of 1.6-2.8 GHz and gain is between 15.3-19.9 dB. It is clear at this point that we can improve the performance of broadband amplifiers by using non-uniform transmission lines as the matching networks.