Patent ID: 7920036

Claim:
A lattice tunable filtering circuit having first and second inputs, and first and second outputs, said circuit comprising: a first branch having a series impedance which is coupled between said first input and said first output; a second branch having a series impedance which is coupled between said second input and said second output; a third branch having a parallel impedance which is coupled between said first input and said second output; a fourth branch having a parallel impedance which is coupled between said second input and said first output, wherein said first and second branches respectively including first and second tunable resonator components with a first series resonance frequency; said third and said fourth branches, respectively including third and fourth tunable resonator components with a second series resonance frequency lower than said first series resonance frequency; and said first and second series resonance frequencies being tunable by an analog control quantity; and a feedback control loop of said analog control quantity based on a criterion of equality related to said serial and parallel impedances.