Patent ID: 7492242
Filing Date: 2009-02-17
Classification: H03H

Abstract:
1. A tunable filter circuit having first and second inputs and first and second outputs, the filter circuit comprising: at least one primary four-pole circuit including, in cascade: a first varactor having a first electrode coupled to said first input and a second electrode; a first inductive resistor having a first electrode coupled to the second electrode of said first varactor and having a second electrode coupled to said second input; a secondary four-pole circuit having first, second, third and fourth bulk acoustic wave (BAW)-type resonators, said secondary four-pole circuit having first and second inputs and first and second outputs, a second inductive resistor having a first electrode coupled to said first output of said secondary four-pole circuit and having a second electrode coupled to the second output of said secondary four-pole circuit; and a second varactor having a first electrode coupled to the first output of said secondary four-pole circuit, and a second electrode.