A dual-band matching network for frequency-dependent complex loads suitable for dual-band RF amplifiers

A dual-band matching network using dual-band coupled line based quarter-wave line is presented. The proposed matching network is capable of providing simultaneous match for frequency-dependent complex loads having different values at two arbitrary frequencies to Z₀ (here, 50Ω). A very simple step-wise evolution of the transformer is shown and closed form design equations are obtained. It is to be noted that since matching networks are usually part of larger systems such as amplifiers, it is customary in literature to show working of such design using simulators. Agilent ADS is used to verify the proposed network. A very good result is obtained confirming the theory. Although, here the discussion is in RF amplifier context, such a transformer will also be of interest to other designers such as designers of mixers and antennas.