SUB-NETWORK ENHANCED REFLECTIONLESS FILTER TOPOLOGY

摘要

Reflectionless low-pass, high-pass, band-pass, band-stop, all-pass, and all-stop filters, as well as a method for designing such filters is disclosed, along with a method of enhancing the performance of such filters through the use of sub-networks to further modify and improve the frequency response. These filters preferably function by absorbing the stop-band portion of the spectrum rather than reflecting it back to the source, which has significant advantages in many different applications. The sub-networks preferably offer additional degrees of freedom by which the leakage through the parent filter may be cancelled or reinforced to alter cutoff sharpness, stop-rejection, or other measures of performance.

主权项

1. A reflectionless electronic filter comprising:
a symmetric two-port circuit, wherein the symmetry defines an even-mode equivalent circuit and an odd-mode equivalent circuit when the ports are driven in-phase and 180° out-of-phase, respectively; at least one lossless element and at least one matched internal sub-network arranged within the symmetric two-port circuit such that:
a normalized input impedance of the even-mode equivalent circuit is substantially equal to a normalized input admittance of the odd-mode equivalent circuit; anda normalized input impedance of the odd-mode equivalent circuit is substantially equal to a normalized input admittance of the even-mode equivalent circuit; wherein each matched internal sub-network provides a matched termination to the stop-band signal path of the reflectionless electronic filter.