General matching network for acoustic wave filters and acoustic resonators
First Claim
1. A radio frequency (RF) signal processing device, the device comprising:
- a common terminal;
a plurality of filters, wherein each of the filters is one of a surface acoustic wave (SAW) filter, a bulk acoustic wave (BAW) filter, and a thin film bulk acoustic resonator (FBAR) filter;
a plurality of matching capacitors corresponding to the plurality of filters, each capacitor having a first electrode directly connected to the corresponding filter and having a second electrode, wherein the second electrodes of all of the matching capacitors are directly connected together to the common terminal; and
one of an inductor and a transmission line connected between the common terminal and ground,wherein capacitance values (C1m, C2m, . . . , Cnm) of the n matching capacitors solve the equations;
(2π
F1)2L(0+C2+C3+ . . . +Cn-1+Cn)=1;
(2π
F2)2L(C1+0+C3+ . . . +Cn-1+Cn)=1;
. . . (2π
Fn)2L(C1+C2+ . . . +Cn-1+0)=1,wherein Ci=(Cim*Ci0) / (Cim+Ci0),wherein Ci0 is the equivalent capacitance value of filter i outside of its passband,wherein L is an inductance value of the one of an inductor and a transmission line connected between the common terminal and ground, andwherein (F1, F2, . . . Fn) are center frequencies of the n filters.
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Abstract
A method and circuit matches a device to n filters, wherein each filter is a SAW filter, BAW filter, or FBAR filter. The method and system: (a) provide an inductor or transmission line connected between a common terminal and ground; (b) provide a plurality of capacitance values (C1m, C2m, . . . , Cnm) each corresponding to one of the n filters; and (c) for each of the n filters, directly connect a first terminal of the filter to either: (1) the common terminal, or (2) a first terminal of a corresponding capacitor having the correspondence capacitance value calculated in step (b), where a second terminal of the corresponding capacitor is directly connected to the common terminal.
31 Citations
9 Claims
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1. A radio frequency (RF) signal processing device, the device comprising:
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a common terminal; a plurality of filters, wherein each of the filters is one of a surface acoustic wave (SAW) filter, a bulk acoustic wave (BAW) filter, and a thin film bulk acoustic resonator (FBAR) filter; a plurality of matching capacitors corresponding to the plurality of filters, each capacitor having a first electrode directly connected to the corresponding filter and having a second electrode, wherein the second electrodes of all of the matching capacitors are directly connected together to the common terminal; and one of an inductor and a transmission line connected between the common terminal and ground, wherein capacitance values (C1m, C2m, . . . , Cnm) of the n matching capacitors solve the equations;
(2π
F1)2L(0+C2+C3+ . . . +Cn-1+Cn)=1;
(2π
F2)2L(C1+0+C3+ . . . +Cn-1+Cn)=1;
. . . (2π
Fn)2L(C1+C2+ . . . +Cn-1+0)=1,wherein Ci=(Cim*Ci0) / (Cim+Ci0), wherein Ci0 is the equivalent capacitance value of filter i outside of its passband, wherein L is an inductance value of the one of an inductor and a transmission line connected between the common terminal and ground, and wherein (F1, F2, . . . Fn) are center frequencies of the n filters. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of matching a device to a plurality (n) of filters each having first and second terminals, wherein each of the filters is one of a surface acoustic wave (SAVV) filter, a bulk acoustic wave (BAW) filter, and a thin film bulk acoustic resonator (FBAR) filter, the method comprising:
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(a) providing one of an inductor and a transmission line connected between a common terminal and ground; (b) determining a plurality of capacitance values (C1m, C2m, . . . , Cnm) each corresponding to one of the n filters by solvinq the equations;
(2π
F1)2L(0+C2+C3+ . . . +Cn-1+Cn)=1;
(2π
F2)2L(C1+0C3+ . . . +Cn-1+Cn)=1;
. . . (2π
Fn)2L(C1+C2+ . . . +Cn-1+0)=1,wherein Ci=(Cim*Ci0) / (Cim+Ci0). wherein Ci0is the equivalent capacitance value of filter i outside of its passband; wherein L is an inductance value of the one of an inductor and a transmission line connected between the common terminal and ground, and wherein (F1, F2, . . . Fn) are center frequencies of the n filters; and (c) for each of the n filters, directly connecting the first terminal of the filter to either;
(1) the common terminal, or (2) a first terminal of a corresponding matching capacitor having the correspondence capacitance value calculated in step (b), where a second terminal of the corresponding matching capacitor is directly connected to the common terminal. - View Dependent Claims (8, 9)
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Specification