DE102004003884A1 - Chip device with resonators and use thereof - Google Patents

Abstract

A chip component is proposed in which at least two resonators operating with acoustic waves are realized on a piezoelectric substrate, which are formed in the same technique but have different resonance frequencies. The device ensures the same temperature response for both resonators and thus a constant frequency spacing.

Description

transmission systems Low output power and range work worldwide at various levels Frequency bands. In Europe, this is the ISM Band (Industrial Science Medical) at 433.92MHz and the relatively new Short Range Device (SRD) band between 869MHz and 870MHz. In the US, on the other hand, the ISM band is often the right one wide band used at 915MHz. More tapes are available u.A. around 315MHz and around 390MHz.

Lots Applications e.g. from Telemetry, Keyless Entry may be licensed in the local bands operate. The underlying transmission systems are subject only the general type approval, the special parameters such as output power, Duty cycle, maximum emission and other parameters are regulated.

The based on the aforementioned transmission system often on technically simple, cost-effective solutions. With increasing use such free frequency bands not least therefore occur more and more sources of interference, the one secure data transmission or a trouble-free Disrupt operation of appropriate components and equipment. Through intensive Use of the band can In-band interference occur by other users. By neighboring frequency bands of other systems, For example, TETRA (Trunk Radio System) operating at 430 MHz, can out-of-band interference on which can also adversely affect systems in the ISM band

easy Radio systems such as e.g. Short range device systems work mostly on a frequency that is simple and inexpensive with a SAW resonator or a simple PLL with binary Generating dividers is. The frequencies used here are often in the middle of the transfer belt. This results in a high in-band susceptibility.

systems however, working on multiple frequencies are less vulnerable. a However, implementing channel operation with SRD systems requires a more elaborate one Frequency synthesis based on a PLL synthesizer or a mission of several different SAW components.

In transmission systems working in different, widely spaced transfer belts (Multiband Systems) is the frequency generation with a VCO and a PLL often not possible, because the frequencies are too far apart. Here are different VCOs and possibly additional ones PLLs needed.

task The present invention is therefore, devices with resonators for the stabilization of oscillator circuits, for at least Two resonant frequencies are designed and easy to manufacture are.

These Task is according to the invention with a Chip component solved with the features of claim 1. advantageous Embodiments of the invention and preferred use of the chip component arise from further claims.

The The invention provides a chip component which is a piezoelectric Substrate comprises. In or on the substrate are at least two with realized acoustic waves operating resonators. These are formed on the same substrate and in the same technique, but for different Resonant frequencies designed.

The Resonators can as bulk wave components better BAW resonators (Bulk Acoustic Wave) be formed. For this purpose, the piezoelectric substrate is on two opposite each other main surfaces provided with electrode layers, wherein a resonator is formed, its resonance frequency of the thickness of the piezoelectric substrate is determined.

The Resonators can also with near-surface working acoustic waves and e.g. designed as SAW resonators be. For this purpose, they have on a surface at least one interdigital transducer on, made of two comb-shaped consists of interleaved sub-electrodes. In the direction of propagation the acoustic wave, such a resonator on both sides be limited acoustic reflection structures.

The Resonators are on a common substrate with the same technique and produced in a manufacturing step and therefore have a constant Frequency difference to each other, because no tolerances in the manufacturing process or in the substrate section or other substrate texture may occur, which could affect the resonant frequency differently. All Therefore resonators also have the same temperature response, so that the temperature dependence the resonant frequency equally affects both resonators and the original one Frequency difference of the resonant frequencies is retained.

It but it is also possible To carry out some of the manufacturing steps for the two resonators separately certain parameters relative to the respective resonance frequency of To optimize the resonator. For example, e.g. for the metallization of the resonators a vapor deposition in different layer thicknesses possible.

The Chip component according to the invention is particularly suitable for use in oscillator circuits, with which the transmission frequency of at different frequencies stabilizing devices can be. The resonance frequencies of the at least two resonators can all lie within a single band (transmission band), where the frequency spacing then corresponds at most to the bandwidth of the transmission band. Possible However, it is also true that the resonant frequencies are far from each other are separated and so in different transmission bands one or more Communication systems are arranged. With such a chip component can Oscillator circuits for the transmitting units of dual and multi-band mobile communication terminals be realized in a component. The chip components according to the invention can also for generating the local oscillator frequency (LO) in receiver systems be used.

Chip components according to the invention can also for Applications in the ISM band or other similar narrowband applications be used. In this case, the maximum frequency spacing .DELTA.f of the resonance frequencies set to a value smaller than the bandwidth B of the respective band. This makes it possible to have two or more transmission channels for the ISM band to create better bandwidth utilization can be. Depending on the load of the tape can thereby the transmission frequency be adjusted by means of one of the resonators to the desired channel, preferably to a channel that is burdened by less interference. In contrast to terminals that only on a frequency within the band, preferably on the Send center frequency of the band and the remaining band areas unused let, thus a trouble-free transmission of the data. In addition, a multiple redundant transmission of the data telegram possible on different frequencies. In a preferred embodiment the maximum frequency spacing Δf is set to a value the approximately half the bandwidth of the band, for example the ISM band, equivalent. Since the ISM band in Europe has a width of 1.74 MHz, is one advantageous frequency separation .DELTA.f with two channels then about 0,827MHz. This provides a good compromise between input filter bandwidth, system selection and overhead in system implementation.

Preferably The resonators are made in SAW technology and as acoustic One-port or two-port resonators formed. In an acoustic One-port resonator is an electroacoustic transducer (interdigital transducer) in the acoustic track adjacent on either side of a reflector. The signal is applied to the two sub-electrodes of the transducer, either as a symmetrical signal with advantageously 180 ° phase difference both sub-electrodes of the interdigital transducer or as unbalanced Signal to only one part electrode, the other part electrode connected to ground.

One SAW two-port resonator comprises at least two interdigital transducers, which form the two electrical gates of the resonator. Also a Two-orbit resonator can be in the acoustic track on both sides of each be limited to a reflector.

One preferred substrate for a chip component according to the invention is quartz. Possible However, it is also other crystalline piezoelectric substrates to be used, in particular from lithium niobate and lithium tantalate. In principle, however, any piezoelectric material is suitable independently of whether it applied in a thin film production process or whether it is sawn out of a single crystal.

According to the invention can be provided be the two or more resonators in parallel and switch means to provide for selective switching between the resonators. Preferably, the piezoelectric substrate is together with the Switching means arranged on a common circuit board. The switching means can then, for example, as pin diodes be formed and, for example, as a concrete component the circuit board soldered be, as well as the piezoelectric substrate, which at least two solderable pads having. Possible however, it is also piezoelectric substrate and optionally also other active or passive components on the circuit board stick and in Drahtbondtechnik electrically to the circuit board to contact.

moreover it is also possible connect each resonator with its own oscillator to the oscillator optimally adapted to the respective resonant frequency of the resonator. The oscillators with the associated Resonators are operated alternately, but can also be used simultaneously operate. That there is no limit to just one oscillator in front.

at designed as a frequency-determining part of an oscillator circuit Chip device, where each resonator with its own oscillator is connected, the switching can be omitted with a switching means. The oscillators are preferably mutually activated, but can also be active at the same time.

Depending on the type of resonator chip component of the invention may under have different oscillator circuits. One-port resonators, which in particular can be connected unsymmetrically (single-ended), are preferably incorporated in oscillator circuits of the Colpitts type. Resonators according to the invention, which are designed as SAW two-port resonators, are preferably incorporated in Pierce-type oscillator circuits. But in principle also other types of oscillator circuits are possible and suitable.

These Oscillator circuits can completely realized on the circuit board, for example by soldering corresponding concrete, passive and active components. It is possible However, also to use a multi-layer circuit board, the has at least two metallization levels. The metallization levels can do it be structured so that in the metallization passive components like resistances, capacities and inductors are realized. Accordingly, a chip device according to the invention be implemented on a circuit board, in which the with The oscillator circuit connected to the resonators at least partially in the form of passive components integrated in the multi-layer substrate is realized.

in the The following is the invention with reference to embodiments and the associated figures explained in more detail.

The Figures serve for a better understanding of the invention, therefore partly schematic and not true to scale executed. Like parts are designated by like reference numerals.

1a shows a chip component according to the invention

1b shows a usable as a resonator SAW Eintorresonator

1c shows a SAW two-resonator

2 shows a schematic representation of an oscillator circuit for two resonators.

3 shows an oscillator circuit for a Pierce oscillator

4 shows an oscillator circuit for a Colpitts oscillator

5 shows the chip device on a circuit board

1a shows a chip component according to the invention, in which two resonators RES1 and RES2 are formed on a substrate SUB. The resonators RES1, RES2, which are preferably designed as SAW components, are arranged in particular in two mutually parallel acoustic tracks on the substrate. Although only two resonators are shown, a chip device according to the invention may comprise further resonators on the substrate. Although the resonators are all of the same type, they can also be implemented in a different technique than SAW.

Because of the low temperature dependence Quartz is preferred as a substrate material. It is also possible, however, others piezoelectric materials for Chip components according to the invention use with SAW resonators, such as lithium niobate and Lithium.

1b shows a known SAW resonator, which can be used in the chip component according to the invention. Such a gate resonator consists of an interdigital transducer IDT whose comb-shaped partial electrodes consisting of metallic strips are pushed into one another such that the electrode fingers arranged on a common grid are alternately connected to one of the two terminals T1, T2. The acoustic track can be bounded on either side by a reflector REF. As a reflector also serve strip-shaped metallization, which are preferably arranged on the same grid as the electrode fingers. It is possible to short the reflector structures and ground in particular.

The Resonant frequency of such a gate resonator is determined in first line after the distance of the electrode fingers, or the grid or Pitch in which the electrode fingers are arranged. In the FIG. 1 shows the metallization structure of a one-port resonator on the left shown while on the right side that usually in the diagram for a resonator used circuit symbol is shown.

1c shows a trained in SAW technology two-port resonator, which has over the one-port resonator another interdigital transducer IDT2, which is arranged immediately adjacent to the first interdigital transducer IDT1. In the simplest embodiment, all electrode fingers and reflector strips are arranged on the same grid, which determines the resonant frequency, even in the case of the acoustic two-port resonator. Two of the ports to which the resonator is connected to a circuit environment may be connected to ground.

A preferred use is a chip component according to the invention as a frequency-determining component in an oscillator circuit. 2 shows a general representation of such Os zillatorschaltung, in which a chip component according to the invention is installed as a frequency-determining component. The oscillator circuit consists of an amplifier AMP, which is connected in a feedback loop to the resonator RES1. For this purpose, behind the output of the amplifier AMP at a branch V, a part of the signal is coupled out, passed through the resonator RES1 and not connected to the amplifier input. With the aid of a phase shifter PS, which is integrated into the feedback circuit before or after the resonator, it is ensured that the feedback circuit is coupled via the resonator in phase with the amplified signal in the amplifier. The phase shift circuit PS takes into account the phase response within the resonator and within the amplifier.

from Chip component according to the invention is in each case only one of the resonators RES1 / RES2 with the oscillator circuit connected. about However, one or more switching means S1, S2 can also be the second or another resonator RES2 connected to the oscillator circuit be, the oscillator then with the resonant frequency of the second Resonator RES2 oscillates. As switching means, for example, pin diodes be provided, which as a concrete components together with the substrate can be arranged on a circuit board. This circuit board can also still the amplifier and the phase shifter circuit as further components.

Will one be in 2 shown oscillator at the RF output RF-OUT connected to an antenna, we obtain a complete transmission device. The circuit then only needs a power supply to the amplifier AMP and a modulation signal. The modulator may be an additional module. Any other modulation methods are suitable, wherein in simple applications preferably amplitude shift keying (ASK), or else frequency-shift keying (FSK) is used.

Next the application as a frequency-determining component in RF transmission units, at which several with the aid of the chip component according to the invention can be preset fixed resonant frequencies can a resonator according to the invention also as "Local Oscillator "(LO) be used. In this function he serves to create a fixed reference frequency, which with a receiving in a receiver High frequency signal is mixed. In this way, the high frequency signal converted into a low frequency intermediate frequency signal (IF frequency) and processed further at this level.

With The invention succeeds in providing two and more LO frequencies in one component available too because of their design as SAW resonators a high quality and therefore a high frequency accuracy and, above all, low phase noise exhibit. The resonators can thereby on almost arbitrary frequencies or arbitrary frequency distances to each other be set. In this way it is possible, a device according to the invention to use in different communication systems based on different frequency bands based.

3 shows a complete circuit diagram for an oscillator circuit, in which a chip component according to the invention can be installed before given to. The circuit is a Pierce oscillator, which is preferably used together with an acoustic two-port resonator. The amplifier stage of the oscillator is a transistor TR with a grounded emitter. The resonator RES is sandwiched between two π-type tuning networks. These networks control the phase shift in the feedback loop and therefore provide a phase shifter circuit to set the correct phase for the oscillation condition. You can also adjust the input and output impedance of the transistor to the desired load.

Next The elements mentioned the oscillator circuit is still made different resistances R, inductors L, parallel capacities CP and can also DC currents blocking capacities CB include. In the illustrated Pierce oscillator can be the output RF-OUT tapped RF frequency despite the relatively low bandwidth of the SAW resonators RES can still be varied within certain limits, by the ratio Lsh / Cph and Ls2 / Cp3 is varied. This can be done with a FSK modulation be used.

4 shows another oscillator circuit of the Colpitts type, which can be realized with a small number of components. This circuit is preferably connected to a SAW gate resonator, but also works with a two-port resonator. The oscillator circuit comprises an inductance L1 and 3 series capacitances C1, C2 and C3. The blocking capacity Cb serves as a DC block, but is often not necessary. The parallel L / C oscillation circuit is preferably set to a resonance frequency which is approximately at the resonance frequency of the SAW resonator RES. Within narrow ranges, the oscillator frequency can still be set or pressed by varying the capacitors C1 to C3 and by varying L1.

5 shows a chip component in which further components are integrated on a circuit board SP next to the substrate SUB. As a circuit Board is a multilayer substrate is used, which consists of at least two dielectric layers on and between which metallization levels ME1, ME2 and ME3 are arranged. As dielectric layers can serve plastic films. However, a circuit board made of a high-quality ceramic, in which passive components can be integrated, is preferred. The metallization levels ME are structured and optionally comprise differently wide conductor track sections. Two adjacent metallization levels can be connected to each other at interconnection points via plated-through holes. These consist, for example, of metallized holes passing through a dielectric layer. From the conductor track sections of one or more metallization levels ME, passive components such as resistances, inductances and capacitances may be formed. In the present case, for example, the lowermost metallization level ME3 is designed as a large-area ground MA, which on the one hand represents a good ground and thus has advantages for the oscillator circuit and on the other hand ensures good shielding.

On the surface the board are at least the substrate SUB and for example as arranged pin-diode device switching means S and arranged electrically with the oscillator circuit on and inside the circuit board SP contacted. The individual components can in SMD construction with the Circuit board connected. The SAW resonator or its Substrate SUB may preferably be arranged in flip-chip design, at the connecting surfaces of the resonator on the surface of the substrate SUB with corresponding solderable contacts on the surface of the circuit board get connected. Possible however, it is also, optionally, one or more components selected as Substrate SUB, circuit means S and amplifier AMP stick to the substrate and over Bond wire technology to connect with the interconnection.

Advantageous it is when the circuit board is multi-layered and made of LTCC (Low Temperature co-fired ceramics) is constructed, and if the oscillator circuit with the exception of the amplifier AMP is integrated into the LTCC in the form of passive components. Of the in particular as a semiconductor component (transistor) formed amplifier AMP can act as another concrete component on the surface of the circuit board Be arranged SP.

ever after integration level can additional components may be provided on the circuit board, for example Logic circuits for generating a modulation.

A Exemplary and advantageous application finds a chip component according to the invention at least two SAW resonators in transmitting units for the ISM band. This has a center frequency of 433.92 MHz and has a bandwidth of 1.74 MHz. Advantageously, only 2 channels can be realized in this band whose frequency spacing is approximately half the bandwidth. With the invention can then transmitter for the ISM band can be realized, serving two or more channels can. With the help of this 2- and multi-channel technology succeeds given In-band and out-of-band sources of interference nevertheless a high data transmission security to ensure. Data security can be increased if the information is independent on both Transmit channels becomes. Is the transmission disturbed on a canal, so the redundant second channel is still available. On the respective channel is switched by the one assigned to the channel Resonator with the oscillator circuit by means of the switching means is connected.

For the said ISM band is a suitable channel spacing, for example at 827 KHz. This distance ensures that for both channels, each one resonator at the corresponding resonant frequency is still sufficiently removed from the band boundary and cause no out-of-band interference can. Suitable resonance frequencies for the the channels determining SAW resonators can then, for example, at 433.3337 and 433.5063 MHz.

On the receiver side can the two channels then with independent local oscillators (LO) based on chip components according to the invention be realized. For a filtering of the signal at an intermediate frequency of 10.7 MHz can the local oscillators then, for example, to a frequency of 423.6337 MHz and 422.8063 MHz are set. Do you mix these LO frequency to the respective transmission frequency or resonance frequency of the Oscillators in the transmission circuit, so you get a result of the mixer the respective intermediate frequency at 10.7 MHz.

Although the invention has been explained with reference to only a few embodiments, it is not limited to these. Particular advantages of the invention in all applications in which frequency-accurate resonators are required with constant frequency spacing, the invention is also characterized by the space-saving Einchiplösung. In addition to the resonators shown, it is also possible to use other resonators, while the substrate material may also differ from the specified materials. The oscillator circuits are not limited to the circuits presented by way of example only. Likewise, the number and location of the resonance frequencies are arbitrary and not limited to the applications specified.

Claims (13)

Chip device with a piezoelectric substrate (SUB), in or on the at least two working with acoustic waves Resonators (RES1, RES2) are realized, wherein the resonators formed in the same technique but are different resonance frequencies exhibit. A chip device according to claim 1, wherein the at least two resonators (RES1, RES2) in SRW technology as acoustic one-port or two-port resonators are formed. A chip device according to claim 1 or 2, wherein the piezoelectric substrate (SUB) consists of quartz. Chip component according to one of claims 1 to 3, wherein the switching means (S) for switching between the at least two resonators (RES1, RES2) are provided. A chip device according to claim 4, wherein the switching means (S) designed as pin diodes and together with the substrate (SUB) are arranged on a circuit board (SP). Chip component according to one of claims 1 to 5, which as a frequency-determining part of an oscillator circuit is formed, wherein the oscillator circuit by switching between the at least two resonators (RES1, RES2) optionally in one the at least two resonant frequencies can oscillate. Chip component according to one of claims 1 to 6, which as a frequency-determining part of an oscillator circuit is formed, each resonator with its own oscillator connected is. Chip component according to one of claims 1 to 7, in which the at least two resonators (RES1, RES2) of the chip component as Eintorresonatoren trained in SAW technology and in which the chip component in one SAW oscillator circuit of a Colpitz oscillator is installed. Chip component according to one of claims 1 to 7, wherein the at least two resonators (RES1, RES2) of the chip component as two-port resonators trained in SAW technology and in which the chip component in one SAW oscillator circuit a Pierce oscillator is installed. Chip component according to one of claims 8 to 9, in which the oscillator circuit together with the substrate (SUB) on a multiple metallization levels (ME1, ME2, ME3) Circuit board (SP) is arranged, in which the oscillator circuit Passive components includes, in the form of metallization structures are formed in the metallization levels of the circuit board. Use of a chip component according to one of claims 1 to 10, in an oscillator for stabilizing the transmitting or Reception frequency of a wireless communication or telemetry Facility. Use according to claim 11, wherein the communication device for a Communication system with a transmission band the bandwidth B is designed, wherein for the maximum distance .DELTA.f between the resonance frequencies of the two resonators, Δf <B. Use according to claim 12, wherein the maximum Distance Δf between the resonant frequencies of the two resonators (RES1, RES2) approximately at half the bandwidth B of the transmission band chosen is: Δf = 0.5 × B.