Build LPFs With Dot-Terminations

摘要

High-frequency lowpass filters with flat passbandrnresponses ideal for digital signal transmissions canrnbe fabricated withmicrostrip dot-terminations.rnLowpass filters with maxi-mally flat group delay are ideal for digital signal trans-mission systems, since they allow pulsed signals to rise and fall smoothly and settle rapidly to final values without distortion. Filters such as the Bessel-Thomson lowpass filter have been used in these applications, although the configuration is reflective at stopband frequencies and can cause signal distortion with impedance mismatches. A better solution is the quasi-Gaussian absorptive lowpass filter, with flat group delay in the passband, good match at all frequencies, and absorptive rather than reflective behavior for stopband signals.