US 12,407,331 B2
Systems and methods for providing a tunable radio frequency bandpass filter with variable cross-coupling
Dereck Bojanowski, Fairport, NY (US)
Assigned to L3Harris Global Communications, Inc., Melbourne, FL (US)
Filed by L3Harris Global Communications, Inc., Melbourne, FL (US)
Filed on Jan. 12, 2024, as Appl. No. 18/411,505.
Prior Publication US 2025/0233579 A1, Jul. 17, 2025
Int. Cl. H03H 11/04 (2006.01)
CPC H03H 11/04 (2013.01) 19 Claims
OG exemplary drawing
 
1. A bandpass filter, comprising:
a plurality of shunt resonators coupled in series and configured to allow signals within a range of frequencies to pass; and
a cross-coupling circuit connected to the plurality of shunt resonators and configured to generate a first transmission zero in a low rejection band of the bandpass filter and generate a second transmission zero in a high rejection band of the bandpass filter;
wherein cross-coupling circuit comprises
a first capacitor having a first variable capacitance tunable to concurrently adjust a position of the first transmission zero in the low rejection band relative to a center frequency of a passband of the bandpass filter and a position of the second transmission zero in the high rejection band of the bandpass filter relative to the center frequency, and
a second capacitor having a non-variable capacitance limiting a distance by which the positions of the first and second transmission zeros can move away from each other.