LTCC-based triplexers for WiMAX front-end modules

In this paper, we present low temperature co-fired ceramic (LTCC)-based triplexers for both transmit (TX) and receive (RX) paths in worldwide interoperability for microwave access (WiMAX) tri-band front-end modules. The triplexer for TX path consists of 2- and 5-GHz lowpass filters, a 3-GHz bandpass filter, and a matching network. All components are fully embedded in an LTCC substrate, and it occupies about 5.0 mm × 3.0 mm with a substrate thickness of 0.5 mm. The triplexer for TX path provides relatively low insertion loss at three passbands with a second-harmonic rejection of more than 30 dB. The triplexer for RX path is composed of three embedded bandpass filters and a matching network. The triplexer for RX path also provides low insertion loss at three passbands and high attenuation at other passbands. The size of the triplexer for RX path is about 5.0 mm × 4.0 mm × 0.5 mm. The measured results of the triplexers are in good agreement with the simulated results.