CPC H04B 1/1036 (2013.01) [H04B 1/0483 (2013.01); H04B 2001/1063 (2013.01); H04B 2001/1072 (2013.01)] | 13 Claims |
1. A radio frequency filter circuit based on a plurality of acoustic wave resonators (AWR) and having a specified notch band and a specified passband, the radio frequency filter circuit and including:
(a) at least one series-arm each including:
(1) a series-arm AWR having an electrostatic capacitance CO and selected to have a resonance frequency and an anti-resonance frequency associated with the series- arm AWR, wherein the anti-resonance frequency is within the specified notch band, and the resonance frequency and the anti-resonance frequency are both spaced apart in frequency from the specified passband; and
(2) a series-arm matching inductor coupled in series with the series-arm AWR to form a first inductor-capacitor circuit and having an inductance value that resonates with the electrostatic capacitance C0 of the series-arm AWR within the specified passband; and
(b) at least one parallel-arm coupled to the at least one series-arm and including:
(1) a parallel-arm AWR having an electrostatic capacitance C0 and selected to have a resonance frequency and an anti-resonance frequency associated with the parallel-arm AWR, wherein the resonance frequency is within the specified notch band, and the resonance frequency and the anti-resonance frequency are both spaced apart in frequency from the specified passband; and
(2) a parallel-arm matching inductor coupled in parallel with the parallel-arm AWR to form a second inductor-capacitor circuit and having an inductance value that resonates with the electrostatic capacitance CO of the parallel-arm AWR within the specified passband;
wherein the anti-resonance frequency of the at least one series-arm and the anti-resonance frequency of the coupled at least one parallel-arm are selected to form a notch filter;
wherein the first inductor-capacitor circuit and the selection of the resonance and anti-resonance frequencies of the at least one series-arm AWR spaced apart from the specified passband makes the at least one series-arm AWR behave like a short-circuit within the specified passband;
wherein the second inductor-capacitor circuit and the selection of the resonance and anti-resonance frequencies of the at least one parallel-arm AWR spaced apart from the specified passband makes the at least one parallel-arm AWR behave like an open circuit within the specified passband.
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