Design of Balun-Integrated Switchable Low-Pass-Bandpass Triplexer

This letter first presents a novel balun-integrated switchable low-pass-bandpass triplexer. All the functional blocks between the transmitter/receiver amplifiers and antenna, i.e., switch, low pass and bandpass filter, and balun, are effectively integrated into the proposed single circuit. Then, less mismatch loss and more compact circuit sizes are obtained. Moreover, the proposed switchable triplexer has eight independently controlled operating modes. The fabricated circuit exhibits wide bandwidth, high low-pass selectivity, and more operating modes.