US 12,640,708 B2 · Multi-frequency capacitance cancellation in an acoustic filter circuit

Abstract

Multi-frequency capacitance cancellation in an acoustic filter circuit is provided. The acoustic filter circuit includes an acoustic resonator configured to resonate in a series resonance frequency to pass a radio frequency (RF) signal. However, the acoustic resonator may create an electrical capacitance that can cause the acoustic resonator to resonate at multiple operating frequencies outside the series resonance frequency, thus compromising performance of the acoustic resonator at these operating frequencies. Herein, a negative capacitance circuit is provided in parallel to the acoustic resonator and configured to present multiple negative capacitances to cancel (or at least reduce) the electrical capacitance at the operating frequencies. As a result, it is possible to improve the performance of the acoustic filter circuit across a broader frequency bandwidth.

Claims20

Dependent claims

An acoustic filter circuit comprising:

an acoustic resonator coupled between an input node and an output node and configured to resonate in a series resonance frequency to pass a radio frequency (RF) signal from the input node to the output node;
and
a negative capacitance circuit coupled in parallel to the acoustic resonator between the input node and the output node and configured to present a plurality of negative capacitances each at a respective one of a plurality of operating frequencies in an operating frequency range nonoverlapping with the series resonance frequency between the input node and the output node.

Dependencies are inferred from the claim text.

Multi-frequency capacitance cancellation in an acoustic filter circuit

Life of this patent

Multi-frequency capacitance cancellation in an acoustic filter circuit

Life of this patent

Abstract

Claims20