WO2021147633A1

WO2021147633A1 - Filter, duplexer, high-frequency front-end circuit, and communication apparatus

Info

Publication number: WO2021147633A1
Application number: PCT/CN2020/141264
Authority: WO
Inventors: 庞慰; 边子鹏
Original assignee: 诺思(天津)微系统有限责任公司
Priority date: 2020-01-22
Filing date: 2020-12-30
Publication date: 2021-07-29
Also published as: CN111224641B; CN111224641A

Abstract

Disclosed are a filter (600), a duplexer, a high-frequency front-end circuit, and a communication apparatus. The filter (600) comprises a plurality of resonators connected in series (S11, S12, S13, S14) and a plurality of resonators connected in parallel (P11, P12, P13, P14), wherein some of the resonators connected in series (S11, S12, S13, S14) and/or some of the resonators connected in parallel (P11, P12, P13, P14) are temperature compensation resonators (TCF); and the temperature compensation resonators (TCF) each comprise a temperature compensation layer (55). A high roll-off requirement and a good temperature characteristic of the filter (600) are realized without affecting the bandwidth of the filter (600), and the minimum degradation of the insertion loss of the filter (600) is achieved while the temperature drift characteristic of the filter (600) is improved.

Description

Filter, duplexer, high-frequency front-end circuit and communication device

Technical field

The present invention relates to the technical field of filters, in particular to a filter, a duplexer, a high-frequency front-end circuit and a communication device.

Background technique

With the development of wireless communication applications, people have higher and higher requirements for data transmission rates. Corresponding to the data transmission rate is the high utilization of spectrum resources and the complexity of the spectrum. The complexity of the communication protocol puts forward strict requirements on the various performance of the radio frequency system. In the radio frequency front-end module, the radio frequency filter plays a vital role. It can filter out the out-of-band interference and noise to meet the requirements of the radio frequency system and The requirements of the communication protocol for the signal to noise ratio.

Radio frequency filters are mainly used in wireless communication systems, such as radio frequency front-ends of base stations, mobile phones, computers, satellite communications, radars, electronic countermeasures systems, and so on. The main performance indicators of radio frequency filters are insertion loss, out-of-band suppression, power capacity, linearity, device size and temperature drift characteristics. Good filter performance can improve the data transmission rate, life and reliability of the communication system to a certain extent. Therefore, the design of high-performance and simplified filters for wireless communication systems is very important. At present, the small-size filter devices that can meet the needs of communication terminals are mainly piezoelectric acoustic wave filters. The resonators that constitute this type of acoustic wave filter mainly include: FBAR (Film Bulk Acoustic Resonator), SMR (Solidly Mounted Resonator, solid-state assembly resonator) and SAW (Surface Acoustic Wave, surface acoustic wave resonator). Among them, the filters manufactured based on the principle of bulk acoustic wave FBAR and SMR (collectively referred to as BAW, bulk acoustic wave resonator) have the advantages of lower insertion loss and faster roll-off characteristics compared to filters manufactured based on the principle of surface acoustic wave SAW. .

Because the piezoelectric materials and metal materials that constitute the acoustic wave resonator both have the characteristics of negative temperature coefficient, that is, when the temperature increases, the resonant frequency of the resonator will move in a certain proportion to the low-frequency direction (temperature drift). In general, the temperature coefficient of SAW is -35ppm/℃～-50ppm/℃, and the temperature coefficient of BAW is -25ppm/℃～-30ppm/℃. Although BAW has obvious performance advantages in terms of temperature drift compared to SAW, in some special application scenarios, such a temperature coefficient will still have an adverse effect on the performance of the RF transceiver system with a filter, such as a filter The variable frequency range from the edge of the passband to the out-of-band suppression is defined, so the existence of the temperature coefficient makes this variable range smaller after considering the temperature drift frequency, which greatly increases the difficulty of filter design.

In order to solve the common temperature drift problem of the filter, a common solution is to add a material that can realize the temperature compensation effect in the resonator. For acoustic wave resonators, this temperature compensation material is usually silicon dioxide, because silicon dioxide has a positive temperature coefficient and can be made through general technological processes. At the same time, it has a low price and is suitable for mass production applications; The material of the compensation layer can also be a positive temperature coefficient material such as polysilicon, borophosphate glass (BSG), chromium (Cr) or tellurium oxide (TeO(x)); the thickness of the temperature compensation layer is generally in the range

(Angstrom) to

between. This type of resonator with temperature-compensated materials is also called a temperature coefficient of frequency (Temperature Coefficient of Frequency, TCF) resonator, which is a component unit of the temperature compensation filter.

However, after the above-mentioned temperature compensation layer is introduced into the resonator, the performance of the resonator deteriorates, which is mainly reflected in the increase of the loss of the resonator and the decrease of the ^{electromechanical coupling coefficient (Kt 2 ).} The loss of the resonator directly affects the passband insertion loss characteristics of the filter, thereby increasing the loss in the RF link and deteriorating the transceiver performance of the RF front-end. The electromechanical coupling coefficient becomes smaller. Under certain frequency conditions, the frequency difference between the series resonance frequency and the parallel resonance frequency of the resonator is reduced. The roll-off characteristics of the filter may be improved, but at the same time the bandwidth of the filter will also be narrowed. In most communication systems, the bandwidth of the filter is proposed according to the system requirements, and the bandwidth cannot be narrowed indefinitely.

Summary of the invention

In view of this, the main purpose of the present invention is to provide a filter, a duplexer, a high-frequency front-end circuit, and a communication device that can achieve the high roll-off requirements and requirements of the filter under the premise of certain bandwidth requirements and insertion loss requirements. Good temperature characteristics.

In order to achieve the above objective, according to one aspect of the present invention, a filter is provided, which includes a plurality of series resonators and a plurality of parallel resonators, and the partial series resonators and/or the partial parallel resonators are temperature-compensated resonators. The temperature compensated resonator includes a temperature compensation layer.

Optionally, the series branch includes a multi-stage series circuit, and all or part of the series resonators in the at least one-stage series circuit are temperature-compensated resonators; and/or, the parallel branch includes a multi-stage parallel circuit, wherein at least one stage is connected in parallel All or part of the parallel resonators in the circuit are temperature-compensated resonators.

Optionally, the number of temperature-compensated resonators in the series branch is 1, and the relationship between its frequency and the frequencies of other series resonators is as follows:

Min(fsp_11, fsp_12, fsp_13……fsp_1n)-fsp_tcf≥delta_FR

Among them, fsp_11 is the parallel resonant frequency of series resonator S11, fsp_12 is the parallel resonant frequency of series resonator S12, fsp_13 is the parallel resonant frequency of series resonator S13...fsp_1n is the parallel resonant frequency of series resonator S1n, fsp_tcf is temperature Complement the parallel resonant frequency of the resonator TCF; delta_FR is the frequency change of the corresponding frequency at -20dB on the right side of the filter passband under high and normal temperature conditions.

Optionally, the number of temperature-compensated resonators in the series branch is greater than or equal to 2. Under normal temperature conditions, the relationship between its frequency and the frequencies of other series resonators is as follows:

Min(fsp_11, fsp_12, fsp_13……fsp_1n)-Max(fsp_tcf1, fsp_tcf2……fsp_tcfn)≥delta_FR

Among them, fsp_11 is the parallel resonant frequency of series resonator S11, fsp_12 is the parallel resonant frequency of series resonator S12, fsp_13 is the parallel resonant frequency of series resonator S13...fsp_1n is the parallel resonant frequency of series resonator S1n; fsp_tcf1 is temperature The parallel resonant frequency of the compensation resonator TCF1, fsp_tcf2 is the parallel resonant frequency of the temperature-compensated resonator TCF2...fsp_tcfn is the parallel resonant frequency of the temperature-compensated resonator TCFn; delta_FR is the corresponding frequency at -20dB on the right side of the filter passband at high temperature and The amount of frequency change under normal temperature conditions.

Optionally, in the parallel branch, the number of temperature-compensated resonators is 1. Under normal temperature, the relationship between its frequency and the parallel resonance frequency is as follows:

Min(fpp_11, fpp_12, fpp_13……fpp_1n)-fpp_tcf≥delta_FL;

Among them, fpp_11 is the parallel resonant frequency of the parallel resonator P11, fpp_12 is the parallel resonant frequency of the parallel resonator P12; fpp_13 is the parallel resonant frequency of the parallel resonator P13...fpp_1n is the parallel resonant frequency of the parallel resonator P1n, fpp_tcf is the temperature Compensate the parallel resonant frequency of the resonator TCF; delta_FL is the frequency change of the corresponding frequency at -20dB on the left side of the filter passband under high and normal temperature conditions.

Optionally, the number of temperature-compensated resonators in the parallel branch circuit is greater than or equal to 2. Under normal temperature conditions, the relationship between their frequency and the parallel resonance frequency is as follows;

Min(fpp_11, fpp_12, fpp_13……fpp_1n)-Max(fpp_tcf1, fpp_tcf2……fpp_tcfn)≥delta_FL

Among them, fpp_11 is the parallel resonant frequency of the parallel resonator P11, fpp_12 is the parallel resonant frequency of the parallel resonator S12, fpp_13 is the parallel resonant frequency of the parallel resonator P13...fpp_1n is the parallel resonant frequency of the parallel resonator P1n; fpp_tcf1 is the temperature The parallel resonant frequency of the compensation resonator TCF1, fpp_tcf2 is the parallel resonant frequency of the temperature-compensated resonator TCF2...fpp_tcfn is the parallel resonant frequency of the temperature-compensated resonator TCFn; delta_FL is the corresponding frequency at the left -20dB of the filter passband at high temperature and The amount of frequency change under normal temperature conditions.

Optionally, the temperature compensation resonator has a positive temperature drift coefficient, and the magnitude of the positive temperature drift coefficient is 0 to 0.5 times the magnitude of the temperature drift coefficient of the resonator without a temperature compensation layer.

Optionally, the effective electromechanical coupling coefficient of the temperature-compensated resonator is smaller than the effective electromechanical coupling coefficient of the resonator without a temperature-compensated layer.

Another aspect of the present invention provides a duplexer including the above-mentioned filter.

In yet another aspect of the present invention, a high-frequency front-end circuit is provided, including the above-mentioned filter.

In yet another aspect of the present invention, there is provided a communication device including the above-mentioned filter.

According to the technical solution of the present invention, among the plurality of series resonators and the plurality of parallel resonators, some of the resonators include a temperature compensation layer, so that the series resonator and/or the parallel resonator become a temperature-compensated resonance with a certain temperature drift coefficient Device.

Compared with the existing ordinary filters or filters in which all resonators are temperature-compensated resonators, it has the following advantages: 1. Does not affect the bandwidth of the filter; 2. The small Kt ² characteristic of the temperature-compensated resonator can effectively improve the filtering The roll-off characteristics on both sides of the pass band of the filter; 3. By designing the thickness of the temperature compensation layer of the temperature compensation resonator, the temperature drift characteristics of the filter can be greatly improved and even the zero temperature drift of the filter can be realized; 4. The loss of temperature-compensated resonators is greater than that of ordinary resonators. The more temperature-compensated resonators are introduced into the filter, the worse the insertion loss of the filter will be. Through the design of local temperature-compensated resonators in the filter , While improving the temperature drift characteristics of the filter, the minimum deterioration of the filter insertion loss is realized.

Description of the drawings

For purposes of illustration and not limitation, the present invention will now be described according to preferred embodiments of the present invention, particularly with reference to the accompanying drawings, in which:

Figure 1 is a circuit diagram of a filter in the prior art;

Fig. 2 is a comparative example, that is, a curve diagram of the insertion loss characteristic of the filter in the prior art and the impedance characteristic of the resonator;

Fig. 3 is a comparative example, that is, the corresponding insertion loss characteristic curve diagram of the filter in the prior art under different temperature environments;

FIG. 4 is a circuit diagram of the filter of the first embodiment in the embodiment of the present invention;

5 is a schematic diagram of an FBAR resonator with a temperature compensation layer added in an embodiment of the present invention;

Figure 6 is a comparison diagram of impedance characteristic curves of the resonator before and after adding a temperature compensation layer;

FIG. 7 is a graph of the insertion loss characteristic of the filter and the impedance characteristic of the resonator according to the first embodiment of the present invention;

8 is a comparison diagram of the insertion loss characteristics of the filters of the first embodiment of the present invention and the comparative example under normal temperature conditions;

FIG. 9 is a comparison diagram of the corresponding three-temperature characteristic curve diagram of the TCF resonator under the condition of zero temperature drift in the first embodiment of the present invention and the three-temperature characteristic curve of the comparative example;

Fig. 10 is an enlarged view of the circled area in Fig. 9;

11 is a comparison diagram of the insertion loss characteristics of the TCF resonator in the first embodiment of the present invention under the condition of zero temperature drift and the comparative example under the conditions of normal temperature and high temperature;

12 is a comparison diagram of the insertion loss characteristics of the TCF resonator in the first embodiment of the present invention with a positive 1MHz temperature drift and a comparative example under normal temperature and high temperature conditions;

Fig. 13 is a circuit diagram of a filter according to a second embodiment of the present invention;

14 is a graph of the insertion loss characteristic of the filter and the impedance characteristic of the resonator according to the second embodiment of the present invention;

15 is a comparison diagram of the insertion loss characteristics of the second embodiment of the present invention and the comparative example under normal temperature conditions;

16 is a circuit diagram corresponding to the third embodiment of the present invention;

FIG. 17 is a graph of the insertion loss characteristic of the filter and the impedance characteristic of the resonator according to the third embodiment of the present invention;

18 is a comparison diagram of the insertion loss characteristics of the third embodiment of the present invention and the comparative example under normal temperature conditions;

19 is a comparison diagram of the insertion loss characteristics under normal temperature conditions between the comparative example and the embodiment 1, the embodiment 2, and the embodiment 3 of the present invention;

FIG. 20 is a circuit diagram of the filter of the fourth embodiment in the embodiment of the present invention;

FIG. 21 is a circuit diagram of the filter of the fifth embodiment in the embodiment of the present invention;

FIG. 22 is a circuit diagram of the filter of the sixth example in the implementation manner of the present invention; FIG.

FIG. 23 is a circuit diagram of the filter of the seventh embodiment in the embodiment of the present invention;

Fig. 24 is a circuit diagram of the filter of the eighth example in the embodiment of the present invention.

Detailed ways

FIG. 1 is a circuit diagram of a filter in the prior art, where T1 is the input terminal of the filter 100, T2 is the output terminal of the filter, and the input terminal T1 and the output terminal T2 are ports connected to the external signal of the filter . Between the input terminal T1 and the output terminal T2, there are a series of series-connected first resonators S11, S12, S13, and S14 at the position of the series path, which are connected in series with each other. Between the input terminal T1 and the series resonator S11, a series inductor L1 is connected in series; between the input terminal T2 and the series resonator S14, a series inductor L2 is connected in series. One end of the parallel resonator P11 is connected to the node between the series resonators S11 and S12, one end of the parallel resonator P12 is connected to the node between the series resonators S12 and S13, and the other ends of the parallel resonators P11 and P12 are connected to each other. One end of the parallel inductor L3 is connected, and the other end of the parallel inductor L3 is grounded; one end of the parallel resonator P13 is connected to the node between the series resonators S13 and S14, and one end of the parallel resonator P14 is connected to the series resonator S14 and the series inductor L2 The nodes between are connected, the other ends of the parallel resonators P13 and P14 are connected to each other and connected to one end of the shunt inductor L4, and the other end of the shunt inductor L4 is grounded.

The series resonator frequencies of the series resonators S11, S12, S13, and S14 are fss1, fss2, fss3, and fss4, respectively, and the parallel resonance frequencies are fsp1, fsp2, fsp3, and fsp4; the series resonances of the parallel resonators P11, P12, P13, and P14 The frequency of the device is fps1, fps2, fps3, and fps4, and the parallel resonance frequency is fpp1, fpp2, fpp3, and fpp4. The series resonator and the parallel resonator realize that the series resonant frequency is different from each other through different designs of the mass load (adjusting the area and thickness of the mass load, etc.).

Fig. 2 is a comparative example, that is, a curve diagram of the insertion loss characteristic of the filter in the prior art and the impedance characteristic of the resonator. The series resonator and the parallel resonator work together to form the passband characteristic of the filter. By setting the series resonant frequencies of the series resonators to be different from each other and ^{the change of Kt 2} of the series resonators, the roll-off characteristics on the right side of the passband of the filter can be effectively improved. Filters using small Kt ² resonators are easy to achieve good roll-off characteristics, but once the design indicators (bandwidth, insertion loss, out-of-band rejection, etc.) determine the Kt ^{2 of the} resonator, the Kt 2 of the resonator is basically determined, so the filter bandwidth and filter Good roll-off characteristics are contradictory. It is difficult to achieve good roll-off characteristics in the design of wide-bandwidth filters under conventional architectures, and under the conditions that the resonator stack in common filters has been determined, the resonator structure can be changed ^{, The Kt 2} change of the 50 Ohm resonator is only about ±0.5%, and the improvement of the filter roll-off characteristics is limited.

Fig. 3 is a comparative example, that is, the corresponding insertion loss characteristic curve diagram of the filter in the prior art under different temperature environments, where the curve with a triangle label is the insertion loss characteristic curve under an environment of 95 degrees Celsius, and the curve with a square label It is the insertion loss characteristic curve under a normal temperature of 25 degrees Celsius, and the curve with a circular label is the insertion loss characteristic curve under a -45 degrees Celsius environment. Since the piezoelectric dielectric material and electrode material of the filter are all negative temperature coefficient materials (-25ppm/℃～-30ppm/℃), and the heat loss of the filter electrode increases under high temperature conditions, the insertion loss characteristic curve under high temperature conditions Compared with the normal temperature characteristic curve, the insertion loss will also drop when it moves to the low frequency direction. Compared with the normal temperature curve, the amplitude-frequency curve of the filter moves to the high frequency direction at low temperature, and the insertion loss becomes better. In general, the filter During operation, most of the energy of the passband signal is transmitted from the input port T1 to the output port T2 through the series resonator. The temperature of the series resonator will be higher than that of the parallel resonator. Therefore, under the same external environment, the frequency drift on the right side of the passband is greater than The amount of frequency drift on the left side of the passband.

4 is a circuit diagram of the filter of the first embodiment of the embodiment of the present invention. Compared with the existing filter, a series resonator in the filter 600 of this embodiment is replaced with a TCF resonance with a temperature compensation layer Resonator (temperature-compensated resonator); in this embodiment, the existing series resonator S12 is replaced with TCF. Through the different design of the thickness of the temperature compensation layer, the different temperature drift characteristics of the TCF resonator are realized.

5 is a schematic diagram of an FBAR resonator with a temperature compensation layer added in an embodiment of the present invention. In FIG. 5, 51 is a semiconductor substrate material, 56 is an air cavity obtained by etching, and the bottom electrode 53 of the thin film bulk acoustic wave resonator Deposited on the

semiconductor substrate

51, 52 is a piezoelectric film material, 54 is a top electrode, and 55 is a temperature compensation layer. The area selected by the dashed line is the overlapping area of the air cavity 56, the top electrode 34, the bottom electrode 33, the temperature compensation layer 55, and the piezoelectric layer 32 as the effective resonance area. The material of the temperature compensation layer can be polysilicon, borophosphate glass (BSG), silicon dioxide (SiO2), chromium (Cr) or tellurium oxide (TeO(x)) and other materials. Among them, the bottom electrode pattern that was originally made once is made twice. Between the two bottom electrode patterns, a temperature compensation layer is made. The material of the temperature compensation layer is generally silicon dioxide, and its pattern is smaller than that of the bottom electrode pattern. . In this way, when the bottom electrode pattern is completely fabricated, the temperature compensation layer is completely wrapped in the bottom electrode material. This manufacturing method can make the temperature compensation layer completely wrapped by the bottom electrode, thereby effectively protecting it from other manufacturing processes. Destroy; In addition, because the electrode materials above and below the temperature compensation layer are connected together at the edges, the performance (loss characteristics) of the resonator is greatly deteriorated due to the parasitic capacitance composed of the three.

Fig. 6 is a comparison diagram of impedance characteristic curves of the resonator before and after adding a temperature compensation layer. After adding the temperature compensation layer, the Kt ^{2 of the} resonator is reduced from 6.0% to 3.0%, Rs is increased from 0.8 ohms to 1.6 ohms, and Rp is reduced from 2800 ohms to 1500 ohms. At the same time, it resonates The temperature coefficient of the device has changed from -25ppm/℃～-30ppm/℃ to about 0ppm/℃～25ppm/℃. It can be seen that with the addition of the temperature compensation layer, Kt ² will be about half of the original, Rs will be increased to about 2 times, and Rp will be reduced to about half. The increase in the loss of the resonator will also lead to a certain extent. Decrease in Q value.

Fig. 7 is a graph of the insertion loss characteristic and the impedance characteristic of the resonator of the first embodiment of the present invention. The series resonant frequency and parallel resonant frequency of the TCF resonator are fss_tcf and fsp_tcf, respectively, and the series resonant frequency and parallel resonant frequency of the S11 resonator The resonant frequencies are fss_11, fsp_11, the series resonant frequency and parallel resonant frequency of the S13 resonator are fss_13, fsp_13, and the series resonant frequency and parallel resonant frequency of the S14 resonator are fss_14 and fsp_14. Under normal temperature conditions, the TCF resonator’s The parallel resonance frequency fsp_tcf has the following relationship with the parallel resonance frequencies fsp_11, fsp_13 and fsp_14 of ordinary resonators S11, S13 and S14:

Min(fsp_11, fsp_13, fsp_14)-fsp_tcf≥delta_FR

Among them, delta_FR is the frequency change of the corresponding frequency at -20dB on the right side of the filter passband under high and normal temperature conditions. The relationship among fss_tcf, fss_11, fss_13, and fss_14 is not limited.

Fig. 8 is a comparison diagram of the insertion loss characteristics of the filters of the first embodiment of the present invention and the comparative example under normal temperature conditions. A series resonator in the first embodiment is a TCF resonator with a temperature compensation layer added. The thickness of the temperature compensation layer satisfies the following conditions: the positive temperature drift effect produced by the temperature compensation layer can fully or partially offset the negative temperature drift effects of all other layers, so that the TCF resonator becomes a temperature compensation resonance with a temperature drift coefficient equal to 0ppm/℃ The positive temperature drift effect of the temperature compensation layer is greater than the negative temperature drift effect of all other layers, so that the TCF resonator becomes a temperature compensation resonator with a positive temperature drift coefficient; because the TCF resonator is added in the first embodiment , The TCF resonator has a small Kt ² characteristic, and the first embodiment can achieve a large improvement in the roll-off characteristic on the right side of the passband without affecting the bandwidth of the filter.

Fig. 9 is a comparison diagram of the three-temperature characteristic curve corresponding to the TCF resonator under the zero temperature drift condition of the first embodiment of the present invention and the three-temperature characteristic curve of the comparative example. As shown in Fig. 9, the TCF resonator corresponds under the zero temperature drift condition The three-temperature characteristic curve (low temperature: -45 degrees Celsius, normal temperature: 25 degrees Celsius, high temperature: 95 degrees Celsius) is a solid line, and the three-temperature characteristic curve of the comparative example is a dashed line. The comparison between the two shows that the right side of the pass band of the first embodiment The temperature drift characteristics have been greatly improved. Figure 10 is an enlarged view of the circled area in Figure 9. The temperature drift on the right side of the passband of the first embodiment is 0.5MHz under high temperature conditions, which is greatly improved compared to the 2MHz temperature drift of the comparative example. At the same time, the temperature drift is at 2150MHz under high temperature conditions. Compared with the comparative example, the insertion loss of the first embodiment is increased by about 3dB.

FIG. 11 is a comparison diagram of the insertion loss characteristics of the TCF resonator in the first embodiment of the present invention under the condition of zero temperature drift and the comparative example under the conditions of normal temperature and high temperature. FIG. 12 is a comparison diagram of the insertion loss characteristics of the TCF resonator in the first embodiment of the present invention with a positive 1MHz temperature drift and a comparative example under normal temperature and high temperature conditions. It can be seen from the figure that the first embodiment achieves the zero temperature drift characteristic on the right side of the filter passband. That is, the reasonable design of the thickness of the temperature compensation layer of the TCF resonator realizes the zero temperature drift characteristic of the filter.

FIG. 13 is a circuit diagram of the filter of the second embodiment of the present invention. Compared with the existing filter, one of the series resonators in the filter 700 in the second embodiment is replaced with a TCF resonator with a temperature compensation layer (Temperature Compensated Resonator): In this embodiment, the existing series resonator S13 is replaced with TCF. Through the different design of the thickness of the temperature compensation layer, the different temperature drift characteristics of the TCF resonator are realized.

14 is a graph of the filter insertion loss characteristic and the resonator impedance characteristic of the second embodiment of the present invention. The series resonance frequency and parallel resonance frequency of the TCF resonator are fss_tcf and fsp_tcf respectively, and the series resonance frequency and parallel resonance frequency of the S11 resonator are The resonant frequencies are fss_11, fsp_11, the series resonant frequency and parallel resonant frequency of the S12 resonator are fss_12, fsp_12, and the series resonant frequency and parallel resonant frequency of the S14 resonator are fss_14 and fsp_14, respectively. Under normal temperature conditions, the TCF resonator's The parallel resonance frequency fsp_tcf has the following relationship with the parallel resonance frequencies fsp_11, fsp_12 and fsp_14 of ordinary resonators S11, S12 and S14:

Min(fsp_11, fsp_12, fsp_14)-fsp_tcf≥delta_FR

Among them, the relationship among fss_tcf, fss_11, fss_13, and fss_14 is not limited.

15 is a comparison diagram of the insertion loss characteristics of the second embodiment of the present invention and the comparative example under normal temperature conditions. As shown in FIG. 15, the same as the first embodiment, because the TCF resonator is added in the second embodiment, the TCF resonates The filter has a small Kt ² characteristic, and the second embodiment can achieve a greater improvement in the roll-off characteristic on the right side of the passband without affecting the bandwidth of the filter.

16 is a circuit diagram corresponding to the third embodiment of the present invention. Compared with the existing filter, the two series resonators in the filter 800 of the third embodiment are replaced with TCF resonators with a temperature compensation layer (temperature compensation layer). Compensation resonator), respectively TCF1 and TCF2; in this embodiment, the TCF1 resonator and TCF2 resonator are replaced with the series resonators S12 and S13 in the comparative example, and the TCF1 resonator and TCF2 resonance are realized through different designs of the temperature compensation layer thickness. Change of temperature drift characteristics of the device.

FIG. 17 is a graph of the insertion loss characteristic and the impedance characteristic of the resonator of the third embodiment of the present invention. As shown in FIG. 17, the series resonance frequency and parallel resonance frequency of the TCF1 resonator are fss_tcf1, fsp_tcf1, and TCF2 resonators, respectively. The series resonant frequency and parallel resonant frequency are fss_tcf2, fsp_tcf2, the series resonant frequency and parallel resonant frequency of S11 resonator are fss_11, fsp_11, and the series resonant frequency and parallel resonant frequency of S14 resonator are fss_14 and fsp_14, respectively. Normal temperature conditions Below, the parallel resonance frequencies fsp_tcf1 and fsp_tcf2 of TCF1 and TCF2 resonators have the following relationship with the parallel resonance frequencies fsp_11 and fsp_14 of ordinary series resonators S11 and S14:

Min(fsp_11, fsp_14)-Max(fsp_tcf1, fsp_tcf2)≥delta_FR

Among them, the relationship between fss_tcf1, fss_tcf2, fss_11, and fss_14 is not limited.

Figure 18 is a comparison diagram of the insertion loss characteristics of the third embodiment of the present invention and the comparative example under normal temperature conditions. As shown in Figure 18, the same as the first and second embodiments, two are added to the series branch. The TCF resonator and the TCF resonator have a small Kt2 characteristic. Therefore, the third embodiment can achieve a large improvement in the roll-off characteristic on the right side of the passband without affecting the bandwidth of the filter.

19 is a comparison diagram of the insertion loss characteristics of the comparative example and the first embodiment, the second embodiment, and the third embodiment of the present invention under normal temperature conditions. There is no TCF resonator in the comparative example, the first embodiment and the second embodiment One of the series resonators is a TCF resonator, and two of the series resonators in the third embodiment are TCF resonators. As mentioned earlier, the Kt ^{2 of the} TCF resonator is reduced compared with the ordinary resonator, Rs is about twice that of the ordinary resonator, and Rp is reduced to about half of the ordinary resonator. The loss of the resonator The increase leads to a decrease in the Q value, so the more TCF resonators included in the filter, the worse the passband insertion loss characteristics, but the better the temperature drift characteristics and roll-off characteristics, so the design process should be based on the design indicators It is required to balance the temperature drift characteristics, roll-off characteristics and passband insertion loss characteristics.

FIG. 20 is a circuit diagram of the filter of the fourth embodiment of the embodiment of the present invention. Compared with the existing filter, the first-stage series circuit of the filter 900 of this embodiment includes two resonators, which are the existing ones. The series resonator S12 and the temperature-compensated resonator TCF. In this embodiment, one of the two resonators in the series circuit of the same stage is set as an ordinary series resonator, and the other is set as a temperature-compensated resonator. The structure is not limited to this. It is also possible to set the two resonators as temperature-compensated resonators; by setting the temperature-compensated resonator, and by designing the thickness of the temperature-compensating layer, different temperature drift characteristics of the TCF resonator can be realized.

FIG. 21 is a circuit diagram of the filter of the fifth embodiment of the embodiment of the present invention. Compared with the existing filter, one of the parallel resonators in the filter 110 of this embodiment is replaced with a temperature-compensated resonator TCF; The temperature compensation resonator, and through the different design of the temperature compensation layer thickness, realizes the different temperature drift characteristics of the TCF resonator.

The series resonance frequency and parallel resonance frequency of the P11 resonator are fps_11 and fpp_11, respectively, the series resonance frequency and parallel resonance frequency of the P13 resonator are fps_13, fpp_13, respectively, and the series resonance frequency and parallel resonance frequency of the P14 resonator are fps_14, fpp_14, respectively The series resonance frequency and parallel resonance frequency of the TCF resonator are fps_tcf and fpp_tcf respectively. Under normal temperature conditions, the parallel resonance frequency fpp_tcf of the TCF resonator and the parallel resonance frequencies fpp_11, fpp_13 and fpp_14 of the ordinary resonators P11, P13 and P14 exist as follows relation:

Min(fpp_11, fpp_12, fpp_14)-fpp_tcf≥delta_FL

Among them, delta_FL is the frequency change of the corresponding frequency at -20dB on the right and left side of the filter passband under high and normal temperature conditions. The relationship between fps_11, fps_12, fps_tcf, and fps_14 is not limited.

22 is a circuit diagram of the filter of the sixth embodiment of the embodiment of the present invention. Compared with the existing filter, the two parallel resonators in the filter 120 of this embodiment are replaced with temperature-compensated resonators, respectively TCF1 and TCF2; By setting the temperature compensation resonator, and through the different design of the temperature compensation layer thickness, the different temperature drift characteristics of the TCF resonator are realized.

The series resonance frequency and parallel resonance frequency of the P11 resonator are fps_11 and fpp_11, respectively. The series resonance frequency and parallel resonance frequency of the P14 resonator are fps_14 and fpp_14, respectively. The series resonance frequency and parallel resonance frequency of the TCF1 resonator are fps_tcf1, fpp_tcf1, respectively. The series resonance frequency and parallel resonance frequency of the TCF2 resonator are fps_tcf2 and fpp_tcf2, respectively. Under normal temperature conditions, the parallel resonance frequencies fpp_tcf1 and fpp_tcf2 of the TCF resonators have the following relationship with the parallel resonance frequencies fpp_11 and fpp_14 of the ordinary resonators P11 and P14:

Min(fpp_11, fpp_14)-Max(fpp_tcf1, fpp_tcf2)≥delta_FL

Among them, delta_FL is the frequency change of the corresponding frequency at -20dB on the right and left side of the filter passband under high and normal temperature conditions. The relationship between fps_11, fps_tcf1, fps_tcf2, and fps_14 is not limited.

FIG. 23 is a circuit diagram of the filter of the seventh embodiment in the embodiment of the present invention. Compared with the existing filter, the one-stage parallel circuit of the filter 900 of this embodiment includes two resonators, each of which is temperature compensated. The resonator TCF and the parallel resonator P12. In this embodiment, one of the two resonators in the parallel circuit of the same level is set as an ordinary parallel resonator, and the other is set as a temperature-compensated resonator. The structure is not limited to this, but can also The two resonators are both set as temperature-compensated resonators; by setting the temperature-compensated resonator, and through different designs of the thickness of the temperature-compensated layer, different temperature drift characteristics of the TCF resonator are realized.

Fig. 24 is a circuit diagram of the filter of the eighth embodiment of the embodiment of the present invention. Compared with the existing filter, in the filter 140 of this embodiment, a temperature-compensated resonator TCF1 is provided in the series branch, which is connected in parallel A temperature-compensated resonator TCF2 is set in the branch, that is, a temperature-compensated resonator is set in both the series branch and the parallel branch; in this embodiment, the temperature-compensated resonator is set, and the thickness of the temperature-compensated layer is designed differently. , To achieve different temperature drift characteristics of the TCF resonator.

In summary, using the technical solution of the present invention, whether it is a filter that is all ordinary FBAR resonators or a filter that is all temperature-compensated resonators, it has obvious advantages in performance, and takes into account the bandwidth and pass of the filter. With roll-off on both sides and passband insertion loss characteristics.

The foregoing specific implementations do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that, depending on design requirements and other factors, various modifications, combinations, sub-combinations, and substitutions can occur. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

A filter comprising a plurality of series resonators and a plurality of parallel resonators, characterized in that:

Part of the series resonator and/or part of the parallel resonator is a temperature-compensated resonator, and the temperature-compensated resonator includes a temperature compensation layer.
The filter according to claim 1, wherein the series branch comprises a multi-stage series circuit, and all or part of the series resonators in the at least one-stage series circuit are temperature-compensated resonators;

And/or,

The parallel branch includes a multi-stage parallel circuit, wherein all or part of the parallel resonators in the at least one-stage parallel circuit are temperature-compensated resonators.
The filter according to claim 1, wherein the number of temperature-compensated resonators in the series branch is 1, and the relationship between its frequency and the frequencies of other series resonators is as follows:

Min(fsp_11, fsp_12, fsp_13……fsp_1n)-fsp_tcf≥delta_FR

Among them, fsp_11 is the parallel resonant frequency of series resonator S11, fsp_12 is the parallel resonant frequency of series resonator S12, fsp_13 is the parallel resonant frequency of series resonator S13...fsp_1n is the parallel resonant frequency of series resonator S1n, fsp_tcf is temperature Complement the parallel resonant frequency of the resonator TCF; delta_FR is the frequency change of the corresponding frequency at -20dB on the right side of the filter passband under high and normal temperature conditions.
The filter according to claim 1, wherein the number of temperature-compensated resonators in the series branch is greater than or equal to 2, and the relationship between its frequency and the frequencies of other series resonators at room temperature is as follows:

Min(fsp_11, fsp_12, fsp_13……fsp_1n)-Max(fsp_tcf1, fsp_tcf2……fsp_tcfn)≥delta_FR

Among them, fsp_11 is the parallel resonant frequency of series resonator S11, fsp_12 is the parallel resonant frequency of series resonator S12, fsp_13 is the parallel resonant frequency of series resonator S13... fsp_1n is the parallel resonant frequency of series resonator S1n; fsp_tcf1 is temperature The parallel resonant frequency of the compensation resonator TCF1, fsp_tcf2 is the parallel resonant frequency of the temperature-compensated resonator TCF2...fsp_tcfn is the parallel resonant frequency of the temperature-compensated resonator TCFn; delta_FR is the corresponding frequency at -20dB on the right side of the filter passband at high temperature and The amount of frequency change under normal temperature conditions.
The filter according to claim 1, characterized in that, in the parallel branch, the number of temperature-compensated resonators is 1, and the relationship between its frequency and the parallel resonance frequency at normal temperature is as follows:

Min(fpp_11, fpp_12, fpp_13……fpp_1n)-fpp_tcf≥delta_FL;

Among them, fpp_11 is the parallel resonant frequency of the parallel resonator P11, fpp_12 is the parallel resonant frequency of the parallel resonator P12; fpp_13 is the parallel resonant frequency of the parallel resonator P13...fpp_1n is the parallel resonant frequency of the parallel resonator P1n, fpp_tcf is the temperature Compensate the parallel resonant frequency of the resonator TCF; delta_FL is the frequency change of the corresponding frequency at -20dB on the left side of the filter passband under high and normal temperature conditions.
The filter according to claim 1, wherein the number of temperature-compensated resonators in the parallel branch is greater than or equal to 2, and the relationship between its frequency and the parallel resonance frequency at normal temperature is as follows;

Min(fpp_11, fpp_12, fpp_13……fpp_1n)-Max(fpp_tcf1, fpp_tcf2……fpp_tcfn)≥delta_FL

Among them, fpp_11 is the parallel resonant frequency of the parallel resonator P11, fpp_12 is the parallel resonant frequency of the parallel resonator S12, fpp_13 is the parallel resonant frequency of the parallel resonator P13...fpp_1n is the parallel resonant frequency of the parallel resonator P1n; fpp_tcf1 is the temperature The parallel resonant frequency of the compensation resonator TCF1, fpp_tcf2 is the parallel resonant frequency of the temperature-compensated resonator TCF2...fpp_tcfn is the parallel resonant frequency of the temperature-compensated resonator TCFn; delta_FL is the corresponding frequency at the left -20dB of the filter passband at high temperature and The amount of frequency change under normal temperature conditions.
The filter according to claim 1, wherein the temperature compensation resonator has a positive temperature drift coefficient, and the magnitude of the positive temperature drift coefficient is 0 of the value of the temperature drift coefficient of the resonator without a temperature compensation layer. To 0.5 times.
The filter according to claim 1, wherein the effective electromechanical coupling coefficient of the temperature-compensated resonator is smaller than the effective electromechanical coupling coefficient of the resonator without a temperature-compensated layer.
A duplexer, characterized by comprising the filter according to any one of claims 1 to 8.
A high-frequency front-end circuit, characterized by comprising the filter according to any one of claims 1 to 8.
A communication device, characterized by comprising the filter according to any one of claims 1 to 8.