A series of fourth-order tubular Bessel lowpass filters (LPFs) offers 3-dB cutoffs from 1 to 22 GHz. Thanks to computer design and tubular construction, the filters maintain impressive groupdelay characteristics with reasonable rejection while extending the 3-dB cutoff specification for 30-Gb/s systems. For example, model LBT-14000 sports a 3-dB point of 14 GHz and 1-dB (0.4 dB) point of 8.4 GHz at 0.6 times the center frequency. The maximum overall length for this filter is 1.25 in. It features an average power rating of 2 W with 50-Ohm impedance. The lowpass filters are designed for operating temperatures from -55 to +85C.