W-band cross-coupled filters and a duplexer on a thin-film substrate for low-cost front-end integration

The development of cross-coupled bandpass filters and a duplexer for W-band transceiver applications on a thin-film substrate is presented. The filter is designed at 94 GHz using the cross-coupling method on a planar thin-film microstrip (TFMS) line platform and fabricated with a thin-film multichip module technology. The developed filter has an insertion loss of 2.5 dB with a 3-dB fractional bandwidth of 12.8%. Combining two cross-coupled filters with T-junction matching, a simple W-band duplexer is developed. The two channels of the duplexer are centered at 80 GHz and 94 GHz having channel bandwidth of 6.5 GHz and 6.7 GHz, respectively, with insertion loss less than 4.3 dB in both channel. The developed passives are compact and show good matching, selectivity, and isolation characteristics, and are suitable for low-cost W-band front-end integration.