A compact dual-frequency transformer for frequency-dependent complex impedance load

A novel single-stub impedance transformer for matching frequency-dependent complex impedance load is presented. The nonlinear equations to design this transformer are derived for different termination types of the stub line. The proposed impedance matching scheme is successfully adapted to the design of input matching network of a low noise transistor. For demonstration, an impedance transformer for a frequency-dependent complex impedance load is simulated and fabricated. The results of both simulation and measurement verify the validity of the proposed method.