CN101128977A - Piezoelectric filter, and duplexer and communications apparatus using the same - Google Patents
Piezoelectric filter, and duplexer and communications apparatus using the same Download PDFInfo
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- CN101128977A CN101128977A CNA2006800063080A CN200680006308A CN101128977A CN 101128977 A CN101128977 A CN 101128977A CN A2006800063080 A CNA2006800063080 A CN A2006800063080A CN 200680006308 A CN200680006308 A CN 200680006308A CN 101128977 A CN101128977 A CN 101128977A
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Abstract
A piezoelectric filter which has a small circuit scale and device size and can reduce a loss, is provided. The piezoelectric filter (1) has an input impedance smaller than an output impedance. The piezoelectric filter (1) comprises an input terminal (101a), an output terminal (101b), series piezoelectric resonators (102a, 102b, 102c), and parallel piezoelectric resonators (103a, 103b, 103c). Among the parallel piezoelectric resonators (103a, 103b, 103c), on an equivalent circuit, a capacitance of a first parallel piezoelectric resonator (103a) close to the input terminal (101a) side is larger than a capacitance of a second parallel piezoelectric resonator (103c) close to the output terminal (101b) side.
Description
Technical field
The present invention relates to a kind of filter of in radio-circuit, using such as the mobile communication terminal of mobile phone, WLAN etc.More specifically, the present invention relates to the piezoelectric filter formed by piezoelectric.
Technical background
For such as integrated parts in mobile phone and the suchlike electronic installation, require to have small size, lightweight and high-performance.Satisfy the piezoelectric filter that the filter example of these requirements is made up of piezoelectric.
Herein, will be with reference to the conventional radio circuit and the peripheral circuit of appended each figure explanation piezoelectric filter.
Figure 28 is the block diagram that the conventional peripheral circuit that comprises piezoelectric filter has been described.In Figure 28, this routine peripheral circuit comprises amplifier 2801, match circuit 2802 and piezoelectric filter 2803.Usually, in the radio communication circuit that uses high-frequency signal, characteristic impedance is 50 ohm.Therefore, piezoelectric filter 2803 is designed to have 50 ohm at its input side and outlet side.Yet in amplifier 2801, its outlet side has and is different from 50 ohm impedance usually.Therefore, in order to reduce the loss that causes because of not matching, between amplifier 2801 outlet sides and piezoelectric filter 2803 input sides, provide match circuit 2802.
By convention, in order to prevent not matching between the input and output, the input side impedance also is different from outlet side impedance (for example, seeing patent documentation 1) in a kind of disclosed filter.Figure 29 is the figure that the impedance of explanation input side is different from the conventional filter of outlet side impedance.In the conventional filter of Figure 29, input impedance and output impedance differ from one another, and can omit match circuit like this between amplifier and piezoelectric filter.The filter of Figure 29 has comprised input terminal 2901, lead-out terminal 2902, input capacitance 2903, output capacitance 2904, inter-stage electric capacity 2905 and dielectric resonator 2906 and 2907.For making input impedance greater than output impedance, input capacitance 2903 is greater than output impedance 2904.Dielectric resonator 2906 is designed to have the resonance frequency that is higher than dielectric resonator 2907.
Patent documentation 1: Japan Patent is openly issued 11-88011 number
Yet because match circuit, the conventional peripheral circuit structure of Figure 28 has bigger circuit scale, therefore is unfavorable for the miniaturization of device and reduces loss.
In addition, in the conventional filter construction of Figure 29, determine inter-stage electric capacity based on the bandwidth of filter.Therefore, between inter-stage electric capacity and the input capacitance do not match or inter-stage electric capacity and output capacitance between do not match and increased loss very unfriendly.
Therefore, the purpose of this invention is to provide the piezoelectric filter that can reduce circuit scale, plant bulk and reduce loss.
Summary of the invention
For reaching above purpose, the present invention has following aspect.The invention provides and comprise input terminal, lead-out terminal, the one or more series voltage resonators that between input terminal and lead-out terminal, are connected in series, and be connected in the two or more parallel piezoelectric resonator devices between input terminal and the lead-out terminal in parallel.In two or more parallel piezoelectric resonator devices, on equivalent electric circuit, the electric capacity of the first parallel piezoelectric resonator device of the most close input terminal side is greater than the electric capacity of the second parallel piezoelectric resonator device of the most close lead-out terminal side.
Preferably, on equivalent electric circuit, these two or more parallel piezoelectric resonator devices can have the electric capacity that reduces successively according to from small to large order of the distance of distance input terminal side, towards the lead-out terminal side.
Preferably, the number of series voltage resonator can be two or more, and in two or more series voltage resonators, on equivalent electric circuit, the electric capacity of the first series voltage resonator of the most close input terminal side can be greater than the electric capacity of the second series voltage resonator of the most close lead-out terminal side.
The present invention also provides a kind of duplexer, and it comprises: antenna terminal, transmitter side terminal, receiver side terminal, be connected the transmitting filter between antenna terminal and the transmitter side terminal, and be connected the receiving filter between antenna terminal and the receiver side terminal.At least one is the piezoelectric filter of input impedance less than output impedance in transmitting filter and the receiving filter.Piezoelectric filter comprise input terminal, lead-out terminal, be connected in series to the one or more series voltage resonators between input terminal and the lead-out terminal and be connected in parallel on input terminal and lead-out terminal between two or more parallel piezoelectric resonator devices.In these two or more parallel piezoelectric resonator devices, on equivalent electric circuit, the electric capacity of the first parallel piezoelectric resonator device of the most close input terminal side is greater than the electric capacity of the second parallel piezoelectric resonator device of the most close lead-out terminal side.
The present invention also provides a kind of communicator, and it comprises: the transmitting filter between transmitter side power amplifier, antenna and antenna and the power amplifier.This transmitting filter is the output impedance conjugation of its input impedance and power amplifier, and the piezoelectric filter of the impedance conjugation of its output impedance and antenna side.This piezoelectric filter comprises one or more series voltage resonators that are connected in series between power amplifier outlet side and the antenna, and comprises two or more parallel piezoelectric resonator devices that are connected in parallel between power amplifier outlet side and the antenna.In two or more parallel piezoelectric resonator devices, on equivalent electric circuit, the electric capacity of the first parallel piezoelectric resonator device of the most close power amplifier side is greater than the electric capacity of the second parallel piezoelectric resonator device of close antenna side.
The present invention also provides a kind of communicator, and it comprises: receiver side low noise amplifier, antenna and the receiving filter that connects between antenna and low noise amplifier.This receiving filter is the piezoelectric filter of the input impedance conjugation of its input impedance and antenna side impedance conjugation and its output impedance and low noise amplifier.This piezoelectric filter comprises the series voltage resonator between one or more input sides that are connected in series in antenna and low noise amplifier, and two or more parallel piezoelectric resonator device that is connected in parallel between antenna and the low noise amplifier input side.In two or more parallel piezoelectric resonator devices, on equivalent electric circuit, the electric capacity of the first parallel piezoelectric resonator device of close antenna side is greater than the electric capacity of the second parallel piezoelectric resonator device of the most close low noise amplifier side.
According to piezoelectric filter of the present invention, because can cause differing from one another of input impedance and output impedance, so can between amplifier and filter, omit match circuit.As a result, can the circuit and the device miniaturization of piezoelectric filter will be needed.
In addition, according to the present invention, no matter what value passband and stopband get, if determined input impedance and output impedance, just can design the piezoelectric filter with suitable passband and stopband feature.Therefore, might in desirable bandwidth, provide and have low-loss piezoelectric filter.
Describe the present invention in conjunction with the drawings, these and other objects of the present invention, feature, aspect, advantage will become apparent.
Description of drawings
Fig. 1 is the equivalent circuit diagram according to the piezoelectric filter 1 of first embodiment of the invention;
Fig. 2 is the sectional view of exemplary configurations of the single piezo-electric resonator of Fig. 1;
Fig. 3 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 101a has 10 ohm characteristic impedance;
Fig. 3 B is the Smith figure of expression reflectance signature, and wherein input terminal 101a has 10 ohm characteristic impedance (with 10 ohm of standardization);
Fig. 4 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 101b has 50 ohm characteristic impedance.
Fig. 4 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 101b has 50 ohm characteristic impedance (with 50 ohm of standardization).
Fig. 5 is the figure of the passband feature of expression piezoelectric filter.
Fig. 6 A is an expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 101a has 10 ohm characteristic impedance.
Fig. 6 B is the Smith figure of expression reflectance signature, and wherein input terminal 101a has 10 ohm characteristic impedance (with 10 ohm of standardization).
Fig. 7 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 101b has 50 ohm characteristic impedance.
Fig. 7 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 101b has 50 ohm characteristic impedance (with 50 ohm of standardization).
Fig. 8 is the figure of the passband feature of expression piezoelectric filter 1.
Fig. 9 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 101a has 5 ohm characteristic impedance.
Fig. 9 B is the Smith figure of expression reflectance signature, and wherein input terminal 101a has 5 ohm characteristic impedance (with 5 ohm of standardization).
Figure 10 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 101b has 50 ohm characteristic impedance.
Figure 10 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 101b has 50 ohm characteristic impedance (with 50 ohm of standardization).
Figure 11 is the figure of the passband feature of expression piezoelectric filter 1.
Figure 12 is the equivalent circuit diagram according to the piezoelectric filter 4 of the 4th embodiment of the present invention.
Figure 13 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 1201a has 10 ohm characteristic impedance.
Figure 13 B is the Smith figure of expression reflectance signature, and wherein input terminal 1201a has 10 ohm characteristic impedance (with 10 ohm of standardization).
Figure 14 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 1201b has 50 ohm characteristic impedance.
Figure 14 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 1201b has 50 ohm characteristic impedance (with 50 ohm of standardization).
Figure 15 is the figure of the passband feature of expression piezoelectric filter 4.
Figure 16 is the equivalent circuit diagram according to the piezoelectric filter 5 of fifth embodiment of the invention.
Figure 17 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 1601a has 10 ohm characteristic impedance.
Figure 17 B is the Smith figure of expression reflectance signature, and wherein input terminal 1601a has 10 ohm characteristic impedance (with 10 ohm of standardization).
Figure 18 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 1601b has 50 ohm characteristic impedance.
Figure 18 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 1601b has 50 ohm characteristic impedance (with 50 ohm of standardization).
Figure 19 is the figure of the passband feature of expression piezoelectric filter 5.
Figure 20 is the equivalent circuit diagram according to the piezoelectric filter 6 of sixth embodiment of the invention.
Figure 21 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 2001a has 50 ohm characteristic impedance.
Figure 21 B is the Smith figure of expression reflectance signature, and wherein input terminal 2001a has 50 ohm characteristic impedance (with 50 ohm of standardization).
Figure 22 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 2001b has 150 ohm impedance.
Figure 22 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 2001b has 150 ohm characteristic impedance (with 150 ohm of standardization).
Figure 23 is the figure of the passband feature of expression piezoelectric filter 6.
Figure 24 A is the figure of the structure of explanation use SAW (Surface Acoustic Wave) resonator and the piezoelectric filter with Figure 20 equivalent electric circuit.
Figure 24 B is the figure of the structure of explanation SAW (Surface Acoustic Wave) resonator.
Figure 25 A is the block diagram of explanation according to the duplexer 2500 of the 8th embodiment.
Figure 25 B is the block diagram of explanation according to the duplexer 2500b of the 8th embodiment.
Figure 26 is the block diagram of explanation according to the structure of the communicator 2600 of the 9th embodiment.
Figure 27 is the block diagram of explanation according to the structure of the communicator 2700 of the tenth embodiment.
Figure 28 is the block diagram that explanation comprises the conventional peripheral circuit of piezoelectric filter.
Figure 29 illustrates that wherein input side impedance is different from the figure of the conventional filter of outlet side impedance.
The reference character explanation
1,4,5,6 piezoelectric filters
The 101a input terminal
The 101b lead-out terminal
The 102a first series voltage resonator
The 102b second series voltage resonator
102c the 3rd series voltage resonator
The 103a first parallel piezoelectric resonator device
The 103b second parallel piezoelectric resonator device
103c the 3rd parallel piezoelectric resonator device
104a first inductance
104b second inductance
104c the 3rd inductance
201 substrates
202 cavitys
203 insulating barriers
204 low electrodes
205 piezoelectric material layers
206 high electrodes
207 oscillating components
208 support sections
209 film bulk acoustic resonator devices
301 on Smith figure the mark at 1850MHz place
302 on Smith figure the mark at 1910MHz place
303 on Smith figure the mark at 1880MHz place
401 on Smith figure the mark at 1850MHz place
402 on Smith figure the mark at 1910MHz place
403 on Smith figure the mark at 1880MHz place
601 on Smith figure the mark at 1850MHz place
602 on Smith figure the mark at 1910MHz place
603 on Smith figure the mark at 1880MHz place
701 on Smith figure the mark at 1850MHz place
702 on Smith figure the mark at 1910MHz place
703 on Smith figure the mark at 1880MHz place
901 on Smith figure the mark at 1850MHz place
902 on Smith figure the mark at 1910MHz place
903 on Smith figure the mark at 1880MHz place
1001 on Smith figure the mark at 1850MHz place
1002 on Smith figure the mark at 1910MHz place
1003 on Smith figure the mark at 1880MHz place
The 1201a input terminal
The 1201b lead-out terminal
1202 series voltage resonators
The 1203a first parallel piezoelectric resonator device
The 1203b second parallel piezoelectric resonator device
1204a first inductance
1204b second inductance
1301 on Smith figure the mark at 1850MHz place
1302 on Smith figure the mark at 1910MHz place
1303 on Smith figure the mark at 1880MHz place
1401 on Smith figure the mark at 1850MHz place
1402 on Smith figure the mark at 1910MHz place
1403 on Smith figure the mark at 1880MHz place
The 1601a input terminal
The 1601b lead-out terminal
The 1602a first series voltage resonator
The 1602b second series voltage resonator
1603 parallel piezoelectric resonator devices
1604 inductance
1701 on Smith figure the mark at 1850MHz place
1702 on Smith figure the mark at 1910MHz place
1703 on Smith figure the mark at 1880MHz place
1801 on Smith figure the mark at 1850MHz place
1802 on Smith figure the mark at 1910MHz place
1803 on Smith figure the mark at 1880MHz place
The 2001a input terminal
The 2001b lead-out terminal
The 2002a first series voltage resonator
The 2002b second series voltage resonator
2002c the 3rd series voltage resonator
The 2003a first parallel piezoelectric resonator device
The 2003b second parallel piezoelectric resonator device
2004a first inductance
2004b second inductance
2005 bypass piezo-electric resonators
2101 on Smith figure the mark at 2110MHz place
2102 on Smith figure the mark at 2170MHz place
2103 on Smith figure the mark at 2140MHz place
2201 on Smith figure the mark at 2110MHz place
2202 on Smith figure the mark at 2170MHz place
2203 on Smith figure the mark at 2140MHz place
2411 Piezoelectric Substrates
The 2412IDT electrode
2413,2414 reflector electrodes
2500, the 2500b duplexer
2501 send terminal
2502 receive terminal
2503 antenna terminals
2504 transmitting filters
2505 phase-shift circuits
2506 receiving filters
2600 communicators
2601 send terminal
2602 baseband portion
2603 power amplifiers
2604 transmitting filters
2605 antennas
2606 receiving filters
2607LNA
2608 receive terminal
2700 communicators
2701,2702 radio block
2703 antennas
2704 switches
2705,2715 send terminal
2706 baseband portion
2707,2716 power amplifiers (PA)
2708 duplexers
2709,2717 transmitting filters
2710UMTS transmission/reception terminal
2711 antenna terminals
2712,2720 receiving filters
2713，2721LNA
2714,2722 receive terminal
2718GSM sends terminal
2719GSM receives terminal
Embodiment
Hereinafter, will be with reference to appended each figure explanation various embodiments of the present invention.
(first embodiment)
Fig. 1 is the equivalent circuit diagram of piezoelectric filter 1 as described in the first embodiment of the present invention.In Fig. 1, this piezoelectric filter 1 comprises input terminal 101a, lead-out terminal 101b, the first series voltage resonator 102a, the second series voltage resonator 102b, the 3rd series voltage resonator 102c, the first parallel piezoelectric resonator device 103a, the second parallel piezoelectric resonator device 103b, the 3rd parallel piezoelectric resonator device 103c, the first inductance 104a, the second inductance 104b and the 3rd inductance 104c.
The first series voltage resonator 102a, the second series voltage resonator 102b and the 3rd series voltage resonator 102c are connected in series between input terminal 101a and the lead-out terminal 101b.The end of the first parallel piezoelectric resonator device 103a is provided between the first series voltage resonator 102a and the second series voltage resonator 102b.The end of the second parallel piezoelectric resonator device 103b is provided between the second series voltage resonator 102b and the 3rd series voltage resonator 102c.The end of the 3rd parallel piezoelectric resonator device 103c is provided between the 3rd series voltage resonator 102c and lead-out terminal.
Between the side that does not link to each other of the first parallel piezoelectric resonator device 103a and ground, provide the first inductance 104a with the first series voltage resonator 102a.Between the side that does not link to each other of the second parallel piezoelectric resonator device 103b and ground, provide the second inductance 104b with the second series voltage resonator 102b.Between the side that does not link to each other of the 3rd parallel piezoelectric resonator device 103c and ground, provide the 3rd inductance 104c with the 3rd series voltage resonator 102c.
The first series voltage resonator 102a has capacitor C s1 and resonance frequency fs1.The second series voltage resonator 102b has capacitor C s2 and resonance frequency fs2.The 3rd series voltage resonator 102c has capacitor C s3 and resonance frequency fs3.The first parallel piezoelectric resonator device 103a has capacitor C p1 and resonance frequency fp1.The second parallel piezoelectric resonator device 103b has capacitor C p2 and resonance frequency fp2.The 3rd parallel piezoelectric resonator device 103c has capacitor C p3 and resonance frequency fp3.The first inductance 104a has inductance value L1.The second inductance 104b has inductance value L2.The 3rd inductance 104c has inductance value L3.
Fig. 2 is the exemplary configurations sectional view of the single piezo-electric resonator of Fig. 1.In Fig. 2,, show a kind of film bulk acoustic resonator device (Film BulkAcoustic Resonator) 209 as the example of piezo-electric resonator.This film bulk acoustic resonator device 209 comprises substrate 201, cavity 202, insulating barrier 203, low electrode 204, piezoelectric material layer 205 and high electrode 206.
Through hole or non through hole that cavity 202 is formed, provided on substrate 201 by silicon or glass substrate etc.Insulating barrier 203 is by silicon dioxide (SiO
2), silicon nitride (Si
3N
4) wait formation, form this layer and be used to cover cavity 202.Low electrode 204 is formed by molybdenum (Mo), aluminium (Al), silver (Ag), tungsten (W), platinum (Pt) etc.Piezoelectric material layer 205 is by aluminium nitride (AlN), zinc oxide (ZnO), lithium niobate (LiNbO
3), lithium tantalate (LiTaO
3), potassium niobate (KNbO
3) wait formation.High electrode 206 is formed by molybdenum (Mo), aluminium (Al), silver (Ag), tungsten (W), platinum (Pt) etc.
Insulating barrier 203, low electrode 204, piezoelectric material layer 205 and high electrode 206 form successively, constitute vibrating mass 207.By this vibrating mass 207 being fixed on the substrate 201 with substrate 201 contacted support components 208.
In film bulk acoustic resonator device 209, by high electrode 206 and low electrode 204 are applied voltage, on piezoelectric material layer 205 electric field appears.The deformation that causes thus is actuated to mechanical oscillation.This vibration is converted to electric resonance or antiresonance characteristic.
Be substantially equal to comprise the anti-resonance frequency of the antiresonant circuit of parallel piezoelectric resonator device 103a, 103b and 103c by the resonance frequency that makes the series resonant circuit that comprises series voltage resonator 102a, 102b and 102c, the piezoelectric filter of Fig. 1 is used as band pass filter, and this filter has the bandwidth of determining according to difference between anti-resonance frequency and the resonance frequency.
The inventor has carried out emulation under the condition (first class value) of the inductance value (equivalent electric circuit constant) of following electric capacity and resonance frequency and each inductance that is provided with each piezo-electric resonator.
(first class value)
Cs1=2.86pF, Cs2=0.88pF, Cs3=0.92pF, Cp1=14.49pF, Cp2=5.29pF, Cp3=2.08pF, fs1=1979.9MHz, fs2=1887.5MHz, fs3=1886.0MHz, fp1=1866.8MHz, fp2=1825.7MHz, fp3=1841.2MHz, L1=1.49nH, L2=0.08nH and L3=1.47nH.In each series voltage resonator 102a, 102b and 102c, and in each parallel piezoelectric resonator device 103a, 103b and 103c, the difference between anti-resonance frequency and the resonance frequency is 50MHz.
Fig. 3 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 101a has 10 ohm characteristic impedance.Fig. 3 B is the Smith figure of expression reflectance signature, and wherein input terminal 101a has 10 ohm characteristic impedance (with 10 ohm of standardization).Fig. 4 A represents reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 101b has 50 ohm characteristic impedance.Fig. 4 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 101b has 50 ohm characteristic impedance (with 50 ohm of standardization).Fig. 5 is the figure of the passband feature of expression piezoelectric filter 1.In Fig. 3 A, Fig. 3 B, Fig. 4 A, Fig. 4 B and Fig. 5, used above-mentioned first class value.
In the Smith of Fig. 3 B figure, mark 301 expression piezoelectric filters 1 are in the impedance at 1850MHz place.In the Smith of Fig. 4 B figure, mark 401 expression piezoelectric filters 1 are in the impedance at 1850MHz place.Because mark 301 and 401 each all be positioned at Smith figure central authorities, can think when using first class value to have at 1850MHz place piezoelectric filter 1 and make reflection coefficient approach zero impedance.
In the Smith of Fig. 3 B figure, mark 302 expression piezoelectric filters 1 are in the impedance at 1910MHz place.In the Smith of Fig. 4 B figure, mark 402 expression piezoelectric filters 1 are in the impedance at 1910MHz place.Because mark 302 and 402 each all near being positioned at Smith figure central authorities, can think when using first class value to have at 1910MHz place piezoelectric filter 1 and make reflection coefficient approach zero impedance.
In the Smith of Fig. 3 B figure, mark 303 expression piezoelectric filters 1 are in the impedance at 1880MHz place.In the Smith of Fig. 4 B figure, mark 403 expression piezoelectric filters 1 are in the impedance at 1880MHz place.Because mark 303 and 403 each all near being positioned at Smith figure central authorities, can think when using first class value to have at 1880MHz place piezoelectric filter 1 and make the approaching zero impedance of reflection coefficient.
As mentioned above, can find in the scope of 1910MHz, to have used the piezoelectric filter 1 of first class value that the impedance of input terminal 101a is complementary with 10 ohm basically, and the impedance of lead-out terminal 101b and 50 ohm are complementary at 1850MHz.Therefore, as shown in Figure 5, used the piezoelectric filter 1 of first class value can be with low-loss transmission 1850 signal to 1910MHz.
On the other hand, as shown in Figure 5, used can significantly decay 1930 to 1990MHz signal of the piezoelectric filter 1 of first class value.
As mentioned above, use the piezoelectric filter 1 of first class value to have in passband (1850 to 1910MHz) with the low-loss transmission signal filter characteristic of deamplification in stopband (1930 arrive 1990MHz).
In used PCS (personal communication service) frequency band of the digital mobile phone service of the U.S., sending frequency band is 1850 to 1910MHz, and frequency acceptance band is 1930 to 1990MHz.Therefore, service is useful for PCS number of bands mobile phone to have used the piezoelectric filter 1 of first class value.
Above-mentioned first class value is characterised in that, capacitor C p1, the Cp2 of parallel piezoelectric resonator device 103a, 103b and 103c and Cp3 are according to the order of the distance (from small to large) of distance input terminal 101a, reduce successively to lead-out terminal 101b.In other words, set up Cp1＞Cp2＞Cp3 relation.Therefore, can obtain having the piezoelectric filter of input impedance less than high decay characteristics in low-loss feature, the expectation stopband in output impedance, the expectation passband.
In this case, the capacitor C s1 of series voltage resonator 102a, 102b and 102c, Cs2 and Cs3 have the relation of Cs1＞Cs3＞Cs2.
Notice that the layer structure of the piezo-electric resonator of Fig. 2 only is used for illustration purpose.Replacedly, can be attached to the upside of high electrode 206 as passivation film, perhaps insulating barrier can be provided between piezoelectric material layer 205 and high electrode 206 or the low electrode 204, thereby obtain similar effect approaching piezoelectric material layer or thin dielectric layer.In the present invention, the layer structure of piezo-electric resonator is not to be limited to this.
Notice that the progression of piezoelectric filter is not limited to situation shown in Figure 1.As long as the electric capacity of parallel piezoelectric resonator device is according to the order of the distance (from small to large) of distance lead-out terminal 101b, raise successively to input terminal 101a, even series voltage resonator number or parallel piezoelectric resonator device number are different from situation shown in Figure 1, also still can obtain similar effects.
(second embodiment)
Have similar equivalent electric circuit as the described piezoelectric filter of second embodiment, therefore can refer again to Fig. 1 with first embodiment.
The inventor has carried out emulation under the condition (second class value) of the inductance value (equivalent electric circuit constant) of following electric capacity and resonance frequency and each inductance that is provided with each piezo-electric resonator.
(second class value)
Cs1=3.06pF, Cs2=1.12pF, Cs3=0.97pF, Cp1=9.95pF, Cp2=4.86pF, Cp3=2.35pF, fp1=1990.0MHz, fs2=1883.3MHz, fs3=1884.0MHz, fp1=1869.7MHz, fp2=1820.2MHz, fp3=1837.4MHz, L1=1.50nH, L2=0.01nH and L3=1.48nH.In each series voltage resonator 102a, 102b and 102c, and in each parallel piezoelectric resonator device 103a, 103b and 103c, the difference between anti-resonance frequency and the resonance frequency is 50MHz.
Shown in second class value, in the piezoelectric filter of second embodiment, capacitor C p1, the Cp2 of parallel piezoelectric resonator device 103a, 103b and 103c and Cp3 be according to the order of the distance (from small to large) of distance input terminal 101a, reduce successively to lead-out terminal 101b, i.e. Cp1＞Cp2＞Cp3.Equally, capacitor C s1, the Cs2 of series voltage resonator 102a, 102b and 102c and Cs3 be according to the order of the distance (from small to large) of distance input terminal 101a, reduce successively to lead-out terminal 101b, i.e. Cs1＞Cs2＞Cs3.
Fig. 6 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 101a has 10 ohm characteristic impedance.Fig. 6 B is the Smith figure of expression reflectance signature, and wherein input terminal 101a has 10 ohm characteristic impedance (with 10 ohm of standardization).Fig. 7 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 101b has 50 ohm characteristic impedance.Fig. 7 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 101b has 50 ohm characteristic impedance (with 50 ohm of standardization).Fig. 8 is the figure of the passband feature of expression piezoelectric filter 1.In Fig. 6 A, Fig. 6 B, Fig. 7 A, Fig. 7 B and Fig. 8, used above-mentioned second class value.
In the Smith of Fig. 6 B and 7B figure, the impedance that mark 601 and 701 each expression 1850MHz (low side of the passband of PCS transmitter side) locate, the impedance that mark 602 and 702 each expression 1910MHz (passband of PCS transmitter side high-end) locate, and the impedance located of mark 603 and 703 each expression 1880MHz (center of the passband of PCS transmitter side).
As Fig. 6 A, Fig. 6 B, Fig. 7 A, Fig. 7 B and shown in Figure 8, the electric capacity of series voltage resonator 102a, 102b and 102c is according to the order of the distance (from small to large) of distance lead-out terminal 101b, increase successively to input terminal 101a, and the electric capacity of parallel piezoelectric resonator device 103a, 103b and 103c is according to the order of the distance (from small to large) of distance lead-out terminal 101b, increase successively to input terminal 101a.Therefore, can obtain the PCS frequency band and send piezoelectric filter, wherein, in the passband (1850 to 1910MHz) of PCS, basically be complementary with 10 ohm in input terminal 101a place's impedance, be complementary with 50 ohm basically in lead-out terminal 101b place's impedance, and with the low-loss transmission signal, in frequency acceptance band (1930 to 1990MHz) as stopband, can the effective attenuation signal.
(the 3rd embodiment)
Have the equivalent electric circuit that is similar to first embodiment as the described piezoelectric filter of the 3rd embodiment, therefore refer again to Fig. 1.
The inventor has carried out emulation under the condition (the 3rd class value) of the inductance value (equivalent electric circuit constant) of following electric capacity and resonance frequency and each inductance that is provided with each piezo-electric resonator.
(the 3rd class value)
Cs1=3.34pF, Cs2=0.72pF, Cs3=0.81pF, Cp1=18.08pF, Cp2=4.22pF, Cp3=2.20pF, fs1=1979.0MHz, fs2=1887.2MHz, fs3=1884.6MHz, fp1=1892.8MHz, fp2=1824.0MHz, fp3=1835.5MHz, L1=1.43nH, L2=0.01nH and L3=1.50nH.In each series voltage resonator 102a, 102b and 102c, and in each parallel piezoelectric resonator device 103a, 103b and 103c, the difference between anti-resonance frequency and the resonance frequency is 50MHz.
Shown in the 3rd class value, in the piezoelectric filter of the 3rd embodiment, capacitor C p1, the Cp2 of parallel piezoelectric resonator device 103a, 103b and 103c and Cp3 be according to the order of the distance (from small to large) of distance input terminal 101a, reduce successively to lead-out terminal 101b, i.e. Cp1＞Cp2＞Cp3.
Fig. 9 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 101a has 5 ohm characteristic impedance.Fig. 9 B is the Smith figure of expression reflectance signature, and wherein input terminal 101a has 5 ohm characteristic impedance (with 5 ohm of standardization).Figure 10 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 101b has 50 ohm characteristic impedance.Figure 10 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 101b has 50 ohm characteristic impedance (with 50 ohm of standardization).Figure 11 is the figure of the passband feature of expression piezoelectric filter 1.In Fig. 9 A, Fig. 9 B, Figure 10 A, Figure 10 B and Figure 11, used above-mentioned the 3rd class value.
In the Smith of Fig. 9 B and 10B figure, the impedance that mark 901 and 1001 each expression 1850MHz (low side of the passband of PCS transmitter side) locate, the impedance that mark 902 and 1002 each expression 1910MHz (passband of PCS transmitter side high-end) locate, and the impedance located of mark 903 and 1003 each expression 1880MHz (center of the passband of PCS transmitter side).
As Fig. 9 A, Fig. 9 B, Figure 10 A, Figure 10 B and shown in Figure 11, the electric capacity of parallel piezoelectric resonator device 103a, 103b and 103c is according to the order of the distance (from small to large) of distance lead-out terminal 101b, increase successively to input terminal 101a.Therefore, can obtain the PCS frequency band and send piezoelectric filter, wherein, in the passband (1850 to 1910MHz) of PCS, basically be complementary with 5 ohm in input terminal 101a place's impedance, be complementary with 50 ohm basically in lead-out terminal 101b place's impedance, and with the low-loss transmission signal, in frequency acceptance band (1930 to 1990MHz) as stopband, can the effective attenuation signal.
Notice that piezoelectric filter of the present invention is not limited to the specified impedance such as 5 ohm, 10 ohm etc.Can be set at appropriate value by value (piezoelectric filter constant) and obtain piezoelectric filter of the present invention, even input impedance can be 5 ohm to the 50 ohm arbitrary values in the scope each device in this piezoelectric filter.
Piezoelectric filter of the present invention is considered to be connected to the output of power amplifier.Therefore, according to the output impedance of power amplifier, can determine the input impedance of piezoelectric filter.
In other words, in order to produce piezoelectric filter of the present invention, this piezoelectric filter can be designed to have input impedance with power amplifier output impedance conjugation.The example process of this design is described below.After the input impedance of determining piezoelectric filter, the equivalent electric circuit constant is set to appropriate value, and produces with the standardized Smith figure of input impedance and with the standardized Smith figure of output impedance.In these Smith figure, if approach zero at expectation passband internal reflection coefficient, and very big at expectation stopband internal reflection coefficient, can think that then the equivalent electric circuit constant that sets is suitable.If keep off in zero at passband internal reflection coefficient, and little at stopband internal reflection coefficient, do not think that then the equivalent electric circuit constant that sets is suitable.Therefore, set new equivalent electric circuit constant in a similar manner so that produce Smith figure, and the observation reflection coefficient.Therefore, if find to obtain the equivalent electric circuit constant of suitable reflection coefficient, use the piezoelectric filter of this equivalence circuit constant to have the input and output impedance of expectation so, and in passband of expecting and stopband, have low-loss and high decay characteristics.
The something in common each other of first to the 3rd embodiment is capacitor C p1, the Cp2 of parallel piezoelectric resonator device 103a, 103b and 103c and Cp3 according to the order of the distance (from small to large) of distance input terminal 101a, reduces successively to lead-out terminal 101b, i.e. Cp1＞Cp2＞Cp3.Therefore, when design piezoelectric filter of the present invention, select the piezoelectric filter constant, make on its equivalent electric circuit, the electric capacity of parallel piezoelectric resonator device is according to the order of the distance (from small to large) of distance input terminal, reduce successively to lead-out terminal in this piezoelectric filter.Thereby obtain having the piezoelectric filter of desired input and output impedance, in desired passband and stopband, have low-loss and high decay characteristics.
In the first and the 3rd embodiment, set up the relation of Cs1＞Cs3＞Cs2.On the contrary, in a second embodiment, set up the relation of Cs1＞Cs2＞Cs3.Therefore, if the electric capacity of parallel piezoelectric resonator device is according to the order of the distance (from small to large) of distance input terminal side, reduce successively to the lead-out terminal side, then why the capacitance settings of series voltage resonator is worth all and can obtains effect of the present invention.Notice that preferably, the electric capacity of the series voltage resonator in first to the 3rd embodiment can be that the electric capacity of input terminal side is greater than the electric capacity of lead-out terminal side, i.e. Cs1＞Cs3 on equivalent electric circuit.In addition, on equivalent electric circuit, the series voltage resonator can have the electric capacity that reduces successively according to the distance of distance input terminal side (from small to large's) order, to the lead-out terminal side.
(the 4th embodiment)
Figure 12 is the equivalent circuit diagram of piezoelectric filter 4 as described in the fourth embodiment of the present invention.The piezoelectric filter 4 of the 4th embodiment is three grades of π type piezoelectric filters.
In Figure 12, piezoelectric filter 4 comprises input terminal 1201a, lead-out terminal 1201b, series voltage resonator 1202, the first parallel piezoelectric resonator device 1203a, the second parallel piezoelectric resonator device 1203b, the first inductance 1204a and the second inductance 1204b.
The inventor has carried out emulation under the condition (the 4th class value) of the inductance value (equivalent electric circuit constant) of following electric capacity and resonance frequency and each inductance that is provided with each piezo-electric resonator.
(the 4th class value)
Shown in the 4th class value, in the piezoelectric filter 4 of the 4th embodiment, the capacitor C p1 of the first parallel piezoelectric resonator device 1203a is greater than the capacitor C p2 of the second parallel piezoelectric resonator device 1203b, i.e. Cp1＞Cp2.
Figure 13 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 1201a has 10 ohm characteristic impedance.Figure 13 B is the Smith figure of expression reflectance signature, and wherein input terminal 1201a has 10 ohm characteristic impedance (with 10 ohm of standardization).Figure 14 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 1201b has 50 ohm characteristic impedance.Figure 14 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 1201b has 50 ohm characteristic impedance (with 50 ohm of standardization).Figure 15 is the figure of the passband feature of expression piezoelectric filter 4.In Figure 13 A, Figure 13 B, Figure 14 A, Figure 14 B and Figure 15, used above-mentioned the 4th class value.
In the Smith of Figure 13 B and 14B figure, the impedance that mark 1301 and 1401 each expression 1850MHz (low side of the passband of PCS transmitter side) locate, the impedance that mark 1302 and 1402 each expression 1910MHz (passband of PCS transmitter side high-end) locate, and the impedance located of mark 1303 and 1403 each expression 1880MHz (center of the passband of PCS transmitter side).
As Figure 13 A, Figure 13 B, Figure 14 A, Figure 14 B and shown in Figure 15, the capacitor C p1 of the first parallel piezoelectric resonator device 1203a is greater than the capacitor C p2 of the second parallel piezoelectric resonator device 1203b.Therefore, in passband (1850 to 1910MHz), can obtain filter characteristic, make to be complementary with 10 ohm basically, be complementary with 50 ohm basically in lead-out terminal 1201b place's impedance in input terminal 1201a place's impedance, and with the low-loss transmission signal.Note, as shown in figure 15, because the piezo-electric resonator number in piezoelectric filter is few to three, so the attenuation in stopband (1930 to 1990MHz) is also little.Yet, can obtain the piezoelectric filter that input impedance and output impedance differ from one another.
According to the 4th embodiment, can find, if the electric capacity of the parallel piezoelectric resonator device of the most close at least input terminal side, then can provide the piezoelectric filter that can send signal with low-loss greater than the electric capacity of the parallel piezoelectric resonator device of the most close lead-out terminal side.Therefore, in piezoelectric filter, except the electric capacity of the parallel piezoelectric resonator device the parallel piezoelectric resonator device at two ends can be less than also can be greater than the electric capacity at the parallel piezoelectric resonator device of input terminal side with three or more parallel piezoelectric resonator devices.In other words, in the example depicted in fig. 1, Cp1＞Cp3＞Cp2 can be set up, also Cp2＞Cp1＞Cp3 can be set up.
Notice that the number of piezoelectric filter is not limited to number shown in Figure 12.Determine the filter number based on desired filter characteristic and stopband attenuation amount.When using three or more piezoelectric filters, can obtain similar effects.
(the 5th embodiment)
Figure 16 is the equivalent circuit diagram of piezoelectric filter 5 as described in the fifth embodiment of the present invention.The piezoelectric filter 5 of the 5th embodiment is three grades of T type piezoelectric filters.In Figure 16, piezoelectric filter 5 comprises input terminal 1601a, lead-out terminal 1601b, the first series voltage resonator 1602a, the second series voltage resonator 1602b, parallel piezoelectric resonator device 1603 and inductance 1604.
The first series voltage resonator 1602a and the second series voltage resonator 1602b are connected in series between input terminal 1601a and the lead-out terminal 1601b.One end of parallel piezoelectric resonator device 1603 is connected between the first series voltage resonator 1202a and the second series voltage resonator 1602b.The other end of parallel piezoelectric resonator device 1603 is by inductance 1604 ground connection.
The inventor has carried out emulation under the condition (the 5th class value) of the inductance value (equivalent electric circuit constant) of following electric capacity and resonance frequency and each inductance that is provided with each piezo-electric resonator.
(the 5th class value)
The first series voltage resonator 1602a has the capacitor C s1 of 2.45pF.The second series voltage resonator 1602b tool. the capacitor C s2 of 1.75pF is arranged.Parallel piezoelectric resonator device 1603 has the capacitor C p of 6.12pF.The first series voltage resonator 1602a has the resonance frequency fs1 of 1987.7MHz.The second series voltage resonator 1602b has the resonance frequency fs2 of 1887.4MHz.Parallel piezoelectric resonator device 1603 has the resonance frequency fp of 1895.6MHz.Inductance 1604 has the inductance value L of 2.61nH.In each of series voltage resonator 1602a and 1602b and parallel piezoelectric resonator device 1603, the difference between anti-resonance frequency and the resonance frequency is 50MHz.
Shown in the 5th class value, in the piezoelectric filter 5 of the 5th embodiment, the capacitor C s1 of the first series voltage resonator 1602a is greater than the capacitor C s2 of the second series voltage resonator 1602b, i.e. Cs1＞Cs2.
Figure 17 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 1601a has 10 ohm characteristic impedance.Figure 17 B is the Smith figure of expression reflectance signature, and wherein input terminal 1601a has 10 ohm characteristic impedance (with 10 ohm of standardization).Figure 18 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 1601b has 50 ohm characteristic impedance.Figure 18 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 1601b has 50 ohm characteristic impedance (with 50 ohm of standardization).Figure 19 is the figure of the passband feature of expression piezoelectric filter 5.In Figure 17 A, Figure 17 B, Figure 18 A, Figure 18 B and Figure 19, used above-mentioned the 5th class value.
In the Smith of Figure 17 B and 18B figure, the impedance that mark 1701 and 1801 each expression 1850MHz (low side of the passband of PCS transmitter side) locate, the impedance that mark 1702 and 1802 each expression 1910MHz (passband of PCS transmitter side high-end) locate, and the impedance located of mark 1703 and 1803 each expression 1880MHz (center of the passband of PCS transmitter side).
As Figure 17 A, Figure 17 B, Figure 18 A, Figure 18 B and shown in Figure 19, the capacitor C s1 of the first series voltage resonator 1602a is greater than the capacitor C s2 of the second series voltage resonator 1602b.Therefore, in passband (1850 to 1910MHz), can obtain filter characteristic, make to be complementary with 10 ohm basically, be complementary with 50 ohm basically in lead-out terminal 1601b place's impedance in input terminal 1601a place's impedance, and with the low-loss transmission signal.Note, because the piezo-electric resonator number in piezoelectric filter is few to three, so the attenuation in stopband (1930 to 1990MHz) is also little.Yet, can obtain the piezoelectric filter that input impedance and output impedance differ from one another.
According to the 5th embodiment, can find, if the electric capacity of the series voltage resonator of the most close at least input terminal side, then can provide the piezoelectric filter that can send signal with low-loss greater than the electric capacity of the series voltage resonator of the most close lead-out terminal side.Therefore, in piezoelectric filter, except the electric capacity of the series voltage resonator the series voltage resonator at two ends can be less than also can be greater than the electric capacity at the series voltage resonator of input terminal side with three or more series voltage resonators.In other words, in the example depicted in fig. 1, can set up Cs1＞Cs3＞Cs2 and also can set up Cs2＞Cs1＞Cs3.
Notice that the number of piezoelectric filter is not limited to number shown in Figure 16.Determine the filter number based on desired filter characteristic and stopband attenuation amount.When using three or more piezoelectric filters, can obtain similar effects.
(the 6th embodiment)
Figure 20 is the equivalent circuit diagram of piezoelectric filter 6 as described in the sixth embodiment of the present invention.In Figure 20, piezoelectric filter 6 comprises input terminal 2001a, lead-out terminal 2001b, the first series voltage resonator 2002a, the second series voltage resonator 2002b, the 3rd series voltage resonator 2002c, the first parallel piezoelectric resonator device 2003a, the second parallel piezoelectric resonator device 2003b, the first inductance 2004a, the second inductance 2004b and bypass piezo-electric resonator 2005.
The first series voltage resonator 2002a and the second series voltage resonator 2002b and the 3rd piezo-electric resonator 2002c are connected in series between input terminal 2001a and the lead-out terminal 2001b successively.The end of the first parallel piezoelectric resonator device 2003a is provided between the first series voltage resonator 2002a and the second series voltage resonator 2002b.The other end of the first parallel piezoelectric resonator device 2003a is passed through the first inductance 2004a ground connection.The end of the second parallel piezoelectric resonator device 2003b is provided between the second series voltage resonator 2002a and the 3rd series voltage resonator 2002c.The other end of the second parallel piezoelectric resonator device 2003b is passed through the second inductance 2004b ground connection.Bypass piezo-electric resonator 2005 is connected between the tie point of the tie point of the first parallel piezoelectric resonator device 2003a and the first inductance 2004a and the second parallel piezoelectric resonator device 2003b and the second inductance 2004b.
The inventor has carried out emulation under the condition (the 6th class value) of the inductance value (equivalent electric circuit constant) of following electric capacity and resonance frequency and each inductance that is provided with each piezo-electric resonator.
(the 6th class value)
The first series voltage resonator 2002a has the capacitor C s1 of 1.91pF.The second series voltage resonator 2002b has the capacitor C s2 of 0.51pF.The 3rd series voltage resonator 2002c has the capacitor C s3 of 1.00pF.The first parallel piezoelectric resonator device 2003a has the capacitor C p1 of 1.89pF.The second parallel piezoelectric resonator device 2003b has the capacitor C p2 of 1.50pF.Bypass piezo-electric resonator 2005 has the capacitor C b of 1.18pF.The first series voltage resonator 2002a has the resonance frequency fs1 of 2137.2MHz.The second series voltage resonator 2002b has the resonance frequency fs2 of 2203.1MHz.The 3rd series voltage resonator 2002c has the resonance frequency fs3 of 2144.9MHz.The first parallel piezoelectric resonator device 2003a has the resonance frequency fp1 of 2090.1MHz.The second parallel piezoelectric resonator device 2003b has the resonance frequency fp2 of 2121.6MHz.Bypass piezo-electric resonator 2005 has the resonance frequency of 1950MHz.The first inductance 2004a has the inductance value L1 of 0.63nH.The second inductance 2004b has the inductance value L2 of 2.97nH.In each of series voltage resonator 2002a, 2002b and 2002c, parallel piezoelectric resonator device 2003a and 2003b and bypass piezo-electric resonator 2005, the difference between anti-resonance frequency and the resonance frequency is 50MHz.Piezoelectric filter 6 is the receiving filters that use at the standard UMTS (universal mobile telecommunications system) that is used for the third generation mobile service.
Shown in the 6th class value, in the piezoelectric filter 6 of the 6th embodiment, the capacitor C p1 of the first parallel piezoelectric resonator device 2003a is greater than the capacitor C p2 of the second parallel piezoelectric resonator device 2003b, i.e. Cp1＞Cp2.In addition, in capacitor C s1, the Cs2 and Cs3 of series voltage resonator 2002a, 2002b and 2002c, the capacitor C s1 of close input terminal 2001a is greater than the capacitor C s2 near lead-out terminal 2001b.
Figure 21 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein input terminal 2001a has 50 ohm characteristic impedance.Figure 21 B is the Smith figure of expression reflectance signature, and wherein input terminal 2001a has 150 ohm characteristic impedance (with 150 ohm of standardization).
Figure 22 A is the figure of expression reflectance signature (changes in amplitude contrast frequency), and wherein lead-out terminal 2001b has 150 ohm characteristic impedance.Figure 22 B is the Smith figure of expression reflectance signature, and wherein lead-out terminal 2001b has 150 ohm characteristic impedance (with 150 ohm of standardization).
Figure 23 is the figure of the passband feature of expression piezoelectric filter 6.In Figure 21 A, Figure 21 B, Figure 22 A, Figure 22 B and Figure 23, used above-mentioned the 6th class value.
In the Smith of Figure 21 B and 22B figure, the impedance that mark 2101 and 2201 each expression 2110MHz (low side of the passband of UMTS receiver) locate, the impedance that mark 2102 and 2202 each expression 2170MHz (passband of UMTS receiver high-end) locate, and the impedance located of mark 2103 and 2203 each expression 2140MHz (center of the passband of UMTS receiver).
As Figure 21 A, Figure 21 B, Figure 22 A, Figure 22 B and shown in Figure 23, the capacitor C p1 of the first parallel piezoelectric resonator device 2003a is greater than the capacitor C p2 of the second parallel piezoelectric resonator device 2003b.Therefore, can obtain filter characteristic, make in passband (2110 to 2170MHz), basically be complementary with 50 ohm in input terminal 2001a place's impedance, basically be complementary with 150 ohm in lead-out terminal 2001b place's impedance, and with the low-loss transmission signal, in stopband (1920 to 1980MHz), signal is significantly decayed.
Like this,, not only can apply the present invention to be connected to the transmitting filter of level behind the power amplifier, and can be applied to be connected to the receiving filter of LNA (low noise amplifier) prime according to the 6th embodiment.
Exemplary design process when applying the present invention to receiving filter will be described below.When applying the present invention to receiving filter, the design piezoelectric filter makes the output impedance of receiving filter and the input impedance conjugation of LNA.After the output impedance of determining piezoelectric filter, the equivalent electric circuit constant is set at suitable value, produced thus with the standardized Smith figure of input impedance with the standardized Smith figure of output impedance.In these Smith figure, if approach zero in desired passband internal reflection rate, and very big in desired stopband internal reflection rate, so just think that the setting of equivalent electric circuit constant is suitable.
If keep off in zero and little in desired passband internal reflection rate, so just do not think that being provided with of equivalent electric circuit constant is inappropriate in stopband internal reflection rate.Therefore, set new equivalent electric circuit constant in a similar manner so that produce Smith figure, and observe reflectivity.If obtain to access the equivalent electric circuit constant of suitable reflectivity by this way, then use the piezoelectric filter of this equivalence circuit constant can have the input and output impedance of expectation, and in desired passband and stopband, have low-loss and high decay characteristics respectively.Select the equivalent electric circuit constant, the electric capacity of parallel piezoelectric resonator device that makes this piezoelectric filter is according to the order of the distance (from small to large) of distance input terminal, reduce successively to lead-out terminal.
Piezoelectric filter of the present invention can be applied to the receiving filter in other communication system outside the UMTS.
As what can see the from the 4th to the 6th embodiment, the present invention is not limited to ladder-type filter circuit.
Though the transmitting filter or the receiving filter that are used in PCS or the UMTS communication system are provided in the above-described embodiments, can have applied the present invention to other communication system outside PCS and the UMTS.Other communication system that how to apply the present invention to except that PCS and UMTS is the problem of design alternative.
(the 7th embodiment)
In the 7th embodiment, explanation is replaced the piezoelectric filter of piezo-electric resonator with SAW (Surface Acoustic Wave) resonator.Have the equivalent electric circuit that is similar to the 6th embodiment as the described piezoelectric filter of the 7th embodiment, therefore, can refer again to Figure 20.
Figure 24 A is that explanation has been used SAW (Surface Acoustic Wave) resonator and had the structure of the piezoelectric filter of Figure 20 equivalent electric circuit.In Figure 24 A, will have with Figure 20 in the components list of corresponding device identity function be shown identical reference number.
By providing interdigital transducer (IDT) electrode and reflector electrode to form SAW (Surface Acoustic Wave) resonator on Piezoelectric Substrates, these electrodes are close to each other in transmission direction.Figure 24 B is the figure of explanation SAW (Surface Acoustic Wave) resonator structure.In Figure 24 B, SAW (Surface Acoustic Wave) resonator is included in IDT electrode 2412 and reflector electrode 2413 and 2414 of being made up of comb electrode on the Piezoelectric Substrates 2411, and this reflector electrode 2413 and 2414 is provided in the both sides of IDT electrode 2412.Ripple by 2412 excitations of IDT electrode is subjected to the restriction of reflector electrode 2413 and 2414, so has obtained the energy constraint resonator.Here, the comb electrode 2412a of composition IDT electrode 2412 and 2412b are corresponding to the input electrode and the output electrode of SAW (Surface Acoustic Wave) resonator itself.Piezoelectric Substrates 2411 is by LiTaO
3, LiNbO
3, formation such as crystal.IDT electrode 2412 and reflector electrode 2413,2414 are formed by Al, Ti, Cu, Al-Cu etc.Particularly, when being applied to transmitting filter, IDT electrode 2412 is preferably formed by the electrode material with high power handling ability.
In the 7th embodiment, suppose that this piezoelectric filter has the equivalent electric circuit constant identical with the 6th class value.Note, be optimized, make it obtain the filter characteristic of expectation by the resonance frequency to SAW (Surface Acoustic Wave) resonator such as the interdigital spacing of adjusting electrode, metallization ratio, thickness of electrode.
Like this, even when being used in SAW (Surface Acoustic Wave) resonator in the piezoelectric filter, can obtain being similar to the effect of the 6th embodiment.In other words, piezo-electric resonator is not limited to film bulk acoustic-wave resonator shown in Figure 2, and can be SAW (Surface Acoustic Wave) resonator.
Equally, in first to the 5th embodiment, when replacing piezo-electric resonator, also can obtain similar effects with SAW (Surface Acoustic Wave) resonator.
Piezo-electric resonator of the present invention can comprise the one or more series voltage resonators that are connected in series between input terminal and the lead-out terminal, and is connected in two or more parallel piezoelectric resonator devices between input terminal and the lead-out terminal in parallel.
In first to the 7th embodiment, as example, the number of supposing the parallel piezoelectric resonator device in the piezoelectric filter is three.Therefore, be the parallel piezoelectric resonator device of close input terminal near the first parallel piezoelectric resonator device of input terminal.Near the second parallel piezoelectric resonator device of lead-out terminal is the parallel piezoelectric resonator device of close lead-out terminal.Yet, when the data of parallel resonator are four or more for a long time, near the first parallel piezoelectric resonator device of the input terminal parallel piezoelectric resonator device of close input terminal not necessarily, and near the second parallel piezoelectric resonator device of the lead-out terminal parallel piezoelectric resonator device of close lead-out terminal not necessarily.
In the present invention, if the electric capacity of the first parallel piezoelectric resonator device of satisfied close input terminal then can make the input and output impedance differ from one another greater than the condition of the electric capacity of the second parallel piezoelectric resonator device of close lead-out terminal.Therefore, in the present invention, the first parallel piezoelectric resonator device is not limited to the parallel piezoelectric resonator device of close input terminal.Equally, the second parallel piezoelectric resonator device is not limited to the parallel piezoelectric resonator device of close lead-out terminal.For the series voltage resonator also is same case.Specifically, if the electric capacity of the first series voltage resonator of satisfied close input terminal then can obtain effect of the present invention greater than the condition of the electric capacity of the second series voltage resonator of close lead-out terminal.
(the 8th embodiment)
In the 8th embodiment, duplexer as first to the 7th described piezoelectric filter of embodiment has been used in explanation.
Figure 25 A is the block diagram that illustrates as the described duplexer 2500 of the 8th embodiment.In Figure 25 A, duplexer 2500 comprises transmission terminal 2501, receives terminal 2502, antenna terminal 2503, transmitting filter 2504, phase-shift circuit 2505 and receiving filter 2506.
Transmitting filter 2504, phase-shift circuit 2505 and receiving filter 2506 are provided at successively and send between terminal 2501 and the reception terminal 2502.Antenna terminal 2503 is connected between transmitting filter 2504 and the phase-shift circuit 2505.
In transmitting filter 2504 and the receiving filter 2506 at least one is as the described piezoelectric filter of first to the 7th embodiment.
As described in first to the 7th embodiment, can design transmitting filter based on the characteristic impedance of antenna terminal 2503 sides and the characteristic impedance of transmission terminal 2501 sides.
As described in first to the 7th embodiment, can design receiving filter based on the characteristic impedance of antenna terminal 2503 sides and the characteristic impedance of transmission terminal 2501 sides.
Notice that the duplexer of the use piezoelectric filter of the 8th embodiment can have the structure shown in Figure 25 B.Figure 25 B is the block diagram of the structure of expression as the described duplexer 2500b of the 8th embodiment.In Figure 25 B, duplexer 2500b comprises reception terminal 2502a and receives terminal 2502b, to replace receiving terminal 2502.
(the 9th embodiment)
In the 9th embodiment, with the communicator of the explanation use as first to the 7th described piezoelectric filter of embodiment.
Figure 26 is the block diagram of expression as the structure of communicator 2609 as described in the 9th embodiment.In Figure 26, communicator 2609 comprises transmission terminal 2601, baseband portion 2602, power amplifier 2603, transmitting filter 2604, antenna 2605, receiving filter 2606, LNA2607 and receives terminal 2608.
Be transmitted through baseband portion 2602 by the signal that sends terminal 2601 inputs, amplify, carry out filtering by transmitting filter 2604, and send from the mode of antenna 2605 with radio wave by power amplifier 2603.2606 pairs of signals that received by antenna 2605 of receiving filter carry out filtering, are amplified by 2607 pairs of these signals of LNA then, and send it to reception terminal 2608 by baseband portion 2602.
In transmitting filter 2604 and the receiving filter 2606 at least one is as the described piezoelectric filter of first to the 7th embodiment.
Specifically, the transmitting filter 2604 of communicator 2609 is piezoelectric filters of impedance conjugation of output impedance conjugation, its output impedance and antenna 2605 sides of its input impedance and power amplifier 2603.As described in first to the 7th embodiment, this piezoelectric filter comprises the one or more series voltage resonators that are connected in series between power amplifier 2603 outlet sides and the antenna 2605, and is connected in the outlet side of power amplifier 2603 and the two or more parallel piezoelectric resonator devices between the antenna 2605 in parallel.On equivalent electric circuit, in two or more parallel piezoelectric resonator devices, the electric capacity of the first parallel piezoelectric resonator device of close power amplifier 2603 sides is greater than the electric capacity of the second parallel piezoelectric resonator device of close antenna 2605 sides.
The receiving filter 2606 of this communicator 2609 is piezoelectric filters of input impedance conjugation of impedance conjugation, its output impedance and the LNA 2607 of its input impedance and antenna 2605 sides.As described in first to the 7th embodiment, this piezoelectric filter comprises the one or more series voltage resonators that are connected in series between antenna 2605 and LNA 2607 input sides, and is connected in the two or more parallel piezoelectric resonator devices between antenna 2605 and the LNA 2607 in parallel.On equivalent electric circuit, in two or more parallel piezoelectric resonator devices, the electric capacity of the first parallel piezoelectric resonator device of close antenna 2605 sides is greater than the electric capacity of the second parallel piezoelectric resonator device of close LNA 2607 sides.
Here, suppose that transmitting filter 2604 and receiving filter 2606 are the described piezoelectric filter as first to the 7th embodiment.
Usually, the characteristic impedance in antenna 2605 sides is 50 ohm.In the characteristic impedance of power amplifier 2603 sides less than 50 ohm.In the characteristic impedance of the input side of LNA 2607 greater than 50 ohm.In the general communication circuit conditions, need between power amplifier and transmitting filter, provide match circuit, and need between LNA and receiving filter, provide match circuit.
Yet, in communicator 2609, will be as the described piezoelectric filter of first to the 7th embodiment as transmitting filter 2604, therefore, can make the characteristic impedance of antenna 2605 sides equal 50 ohm, and the characteristic impedance that can make power amplifier 2603 sides is less than 50 ohm (for example, 5 ohm or 10 ohm), and might stop frequency acceptance band by sending frequency band.In addition, in communicator 2609, to be used as receiving filter 2606 as the piezoelectric filter of first to the 7th embodiment, and therefore can make the characteristic impedance of antenna 2605 sides is 50 ohm, and the characteristic impedance that can make LNA 2607 sides greater than 50 ohm (for example, 150 ohm), may stop the transmission frequency band by frequency acceptance band.
Therefore, as described in the 9th embodiment, do not need to provide match circuit, can provide undersized communicator like this.
Though, in the 9th embodiment,, be used to provide the position of piezoelectric filter to be not limited to these providing piezoelectric filter of the present invention with respect to the back level of power amplifier 2603 or in prime with respect to LNA2607.
(the tenth embodiment)
In the tenth embodiment, explanation is different from a kind of communicator of the 9th embodiment.
Figure 27 is the block diagram of the structure of expression as the described communicator 2700 of the tenth embodiment.In Figure 27, in communicator 2700, the radio-frequency module that radio-frequency module that sends simultaneously and receive and interim switching send and receive is also deposited.To the operation of the communicator 2700 of the tenth embodiment be described, wherein UMTS (universal mobile telecommunications system) radio-frequency module 2701 is used as the radio-frequency module that sends and receive simultaneously, and with the radio-frequency module of GSM (Global Systems for Mobile communications) radio-frequency module 2702 as interim switching transmission and reception.
In antenna 2703 sides, radio- frequency module 2701 and 2702 is separated by switch 2704.Simultaneously, the transmission of GSM radio-frequency module 2702 and reception are separated by switch 2704.
In the UMTS transmitting system, transmit from sending the signal of terminal 2705 inputs by baseband portion 2706, and in power amplifier 2707, this signal is amplified, carry out filtering by the transmitting filter 2709 that is included in the duplexer 2708 again, transmit this signal by UMTS transmission/reception terminal 2710 and the antenna terminal 2711 that in switch 2704, forms, and send this signal with the electric wave form from antenna 2703.In the UMTS receiving system, transmit the signal that receives from antenna 2703 by antenna terminal 2711 and UMTS transmission/reception terminal 2710, and it is carried out filtering by the receiving filter 2712 that comprises in the duplexer 2708, amplify by LNA2713, and this signal is passed to reception terminal 2714 by baseband portion 2706.
Similarly, in the GSM transmitting system, transmit from sending the signal of terminal 2715 inputs by baseband portion 2706, and in power amplifier 2716, it is amplified, by transmitting filter 2717 to its filtering, send terminal 2718 and antenna terminal 2711 transmission by the GSM that in switch 2704, forms, and send from antenna 2703 with the electric wave form.In the GSM receiving system, receive terminal 2719 by antenna terminal 2711 and GSM and transmit the signal that receives from antenna 2703, and carry out filtering by 2720 pairs of these signals of receiving filter, by LNA2721 it is amplified, and send it to by baseband portion 2706 and to receive terminal 2722.
At least one is the piezoelectric filter 2720 of first to the 7th embodiment in transmitting filter 2709, receiving filter 2712, transmitting filter 2717 and the receiving filter 2720.Therefore, as described in the tenth embodiment, can omit match circuit, thereby a undersized communicator is provided.
Though in the tenth embodiment, piezoelectric filter of the present invention is used in the back level of power amplifier 2707 and 2716 or is used in the prime of LNA2713 and 2721, is to use the part of piezoelectric filter to be not limited to this.
By the detailed description of the present invention in conjunction with appended each figure, these or other target of the present invention, feature, aspect and advantage become more apparent.
Industrial applicibility
Piezoelectric filter of the present invention has small size, and has height and decline in the stopband of expectation Decrement has the low-loss feature in passband, therefore, can used as such as mobile phone, Wave filter in the radio-circuit of the mobile communication terminals such as WLAN or similar device. Also can With according to this specification, piezoelectric filter of the present invention is applied to filtering such as radio station In the such application of device.
Claims (6)
1. piezoelectric filter comprises:
Input terminal;
Lead-out terminal;
Be connected in series in the one or more series voltage resonators between described input terminal and the described lead-out terminal; And
Be connected in the two or more parallel piezoelectric resonator devices between described input terminal and the described lead-out terminal in parallel,
Wherein, on equivalent electric circuit, in described two or more parallel piezoelectric resonator devices, the electric capacity of the first parallel piezoelectric resonator device of the most close described input terminal side is greater than the electric capacity of the second parallel piezoelectric resonator device of the most close described lead-out terminal side.
2. piezoelectric filter as claimed in claim 1, wherein, on equivalent electric circuit, described two or more parallel piezoelectric resonator utensils have the electric capacity that reduces successively according to apart from from small to large order of the distance of described input terminal side, towards described lead-out terminal side.
3. piezoelectric filter as claimed in claim 1, wherein:
The number of described series voltage resonator is two or more; And
On equivalent electric circuit, in described two or more series voltage resonators, the electric capacity of the first series voltage resonator of the most close described input terminal side is greater than the electric capacity of the second series voltage resonator of the most close described lead-out terminal side.
4. duplexer comprises:
Antenna terminal;
The transmitter side terminal;
The receiver side terminal;
Be connected the transmitting filter between described antenna terminal and the described transmitter side terminal; And
Be connected the receiving filter between described antenna terminal and the described receiver side terminal,
Wherein, at least one is the piezoelectric filter of input impedance less than output impedance in described transmitting filter and the described receiving filter, and
Described piezoelectric filter comprises:
Input terminal;
Lead-out terminal;
Be connected in series in the one or more series voltage resonators between described input terminal and the described lead-out terminal; And
Be connected in the two or more parallel piezoelectric resonator devices between described input terminal and the lead-out terminal in parallel.
Wherein, on equivalent electric circuit, in described two or more parallel piezoelectric resonator devices, the electric capacity of the first parallel piezoelectric resonator device of the most close described input terminal side is greater than the electric capacity of the second parallel piezoelectric resonator device of the most close described lead-out terminal side.
5. communicator comprises:
The transmitter side power amplifier;
Antenna; And
Be connected the transmitting filter between described antenna and the described power amplifier,
Wherein, described transmitting filter is the output impedance conjugation of its input impedance and described power amplifier, and the piezoelectric filter of the impedance conjugation of its output impedance and described antenna side, and
Described piezoelectric filter comprises:
Be connected in series in the outlet side of described power amplifier and the one or more series voltage resonators between the described antenna; And
Be connected in the outlet side of described power amplifier and the two or more parallel piezoelectric resonator devices between the described antenna in parallel,
Wherein, on equivalent electric circuit, in described two or more parallel piezoelectric resonator devices, the electric capacity of the first parallel piezoelectric resonator device of the most close described power amplifier side is greater than the electric capacity of the second parallel piezoelectric resonator device of close described antenna side.
6. communicator comprises:
The receiver side low noise amplifier;
Antenna; And
Be connected the receiving filter between described antenna and the described low noise amplifier,
Wherein, described receiving filter is the impedance conjugation of its input impedance and described antenna side, and the piezoelectric filter of the input impedance conjugation of its output impedance and described low noise amplifier, and
Described piezoelectric filter comprises:
Be connected in series to the one or more series voltage resonators between the input side of described antenna and described low noise amplifier; And
Be connected in the two or more parallel piezoelectric resonator devices between the input side of described antenna and described low noise amplifier in parallel,
Wherein, on equivalent electric circuit, in described two or more parallel piezoelectric resonator devices, the electric capacity of the first parallel piezoelectric resonator device of close described antenna side is greater than the electric capacity of the second parallel piezoelectric resonator device of the most close described low noise amplifier side.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005054897 | 2005-02-28 | ||
| JP054897/2005 | 2005-02-28 | ||
| JP054898/2005 | 2005-02-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101128977A true CN101128977A (en) | 2008-02-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2006800063080A Pending CN101128977A (en) | 2005-02-28 | 2006-02-21 | Piezoelectric filter, and duplexer and communications apparatus using the same |
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| CN (1) | CN101128977A (en) |
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