CN206056613U - A kind of acoustic wave sensor reading circuit - Google Patents

Abstract

The utility model discloses a kind of acoustic wave sensor reading circuit, including BAW agitators and frequency detection circuit；BAW agitators include that FBAR and other basic circuit elements, FBAR and basic circuit elements are connected by Pierce topological structure；Frequency detection circuit includes six-port network, four energy meters and standard termination, the output port of BAW agitators is connected with the port one of six-port network, standard termination is connected with the port two of six-port network, and four energy meters are connected with other four ports of six-port network respectively；BAW agitators provide radio-frequency input signals for frequency detection circuit；The systematic parameter of six-port network is, by being connected to radio frequency source in port one, to change four various criterions in port two and load to measure obtained by the corresponding energy meter reading of different frequency and reflection coefficient；This utility model can be used for the detection of BAW oscillator frequencies and BAW sensor reading circuit, and simple structure, easy of integration and real-time are high.

Description

A kind of acoustic wave sensor reading circuit

Technical field

This utility model belongs to mems device field, and in particular to a kind of body based on six-port reflectometer Sound wave（BAW, bulk acoustic wave）Sensor readout circuit, the BAW sensor reading circuit of the structure have structure Simply, easy of integration and real-time is high（Frequency sweep is not required to during measurement）The characteristics of.

Background technology

Bulk acoustic wave（BAW, bulk acoustic wave）Sensor is a kind of novel sensor of high speed development, is had Sensitivity is high, quasi- digital output, and the features such as be easy to integrated and operating frequency high, and application prospect is extensive.BAW sensor by Research is can be applicable in the detection of quality, ultraviolet, mercury ion, gas, biology and acceleration etc..BAW sensor is by thin Film body acoustic resonator（FBAR）To sense measured physical quantity（Such as：Quality, ultraviolet, mercury ion, gas, biology and acceleration Deng）, then by reading circuit detecting the resonance frequency shift amount of FBAR, finally FBAR resonance frequency shifts amount is substituted into Measured physical quantity is obtained in FBAR resonant frequencies and the functional relation of measured physical quantity.But, it is independent of Network Analyzer, easily The BAW sensor radiofrequency signal reading circuit integrated with gauge outfit realize, has become that BAW sensor is integrated, practical to be total to One of property bottleneck problem.In order to promote the practical of BAW sensor to need to be designed reading circuit.

The reading circuit of BAW sensor is realized generally using Impedance Analysis and BAW agitators method.Wherein, author：It is yellow Zhenhua, Gao Yang, Cai Xun et al. " the acoustic wave sensor reading circuit [J] based on six-port reflectometer. piezoelectricity and acousto-optic, 2015（6）:1066-1070. ", discloses a kind of BAW sensor reading circuit based on six-port reflectometer, the circuit theory It is as follows：When six-port network DUT ports connect be FBAR when, by radio-frequency signal generator be directed to all six-port reflectometers Operating frequency frequency scan, each Frequency point in the six-port reflectometer operating frequency can obtain the reflection of FBAR Coefficient（The reflection coefficient of FBAR and frequency curve i.e. in six-port reflectometer operating frequency）, by the maximum for finding reflection coefficient Minima and obtain the resonant frequency of FBAR（Frequency corresponding to reflection coefficient maximum/little value is respectively parallel/serial resonance frequency Rate）, this is the resonant frequency for measuring FBAR based on six-port reflectometer by Impedance Analysis.The shortcoming of the program is to read electricity The radio-frequency signal generator that road needs frequency band wider providing radiofrequency signal, the general radio frequency source larger using volume, because This, the wider radio-frequency signal generator of frequency band is difficult to integrated, and needs in measurement process for a wider frequency All frequencies in band carry out sweep measurement, and required time of measuring length is difficult to measurement in real time.

The reading circuit that BAW agitators method is realized is the radio-frequency signal generator that FBAR is designed to a single-frequency point, and The resonance frequency shift amount of FBAR is obtained by the frequency detection circuit detection of BAW agitators, only single-frequency point measurement, institute need to be carried out Need that time of measuring is extremely short to can be used in real time measurement.Thus, the frequency detection circuit of BAW agitators is that BAW agitator methods realize BAW One important step of sensor readout circuit.

Utility model content

This utility model is in order to solve above-mentioned technological deficiency, there is provided a kind of acoustic wave sensor reading circuit, is to be based on The acoustic wave sensor output signal reading circuit of six-port reflectometer, provides based on six-port reflectometer for BAW agitators Frequency detection circuit model, provide solution for BAW sensor reading circuit so that BAW sensor smallerization with And real-time is higher.

For achieving the above object, this utility model takes technical scheme below：

A kind of acoustic wave sensor reading circuit, it is characterised in that：Including bulk acoustic wave（BAW）Agitator and frequency detecting electricity Road；BAW agitators include FBAR（FBAR）With other basic circuit elements, FBAR and other basic circuit units Part is attached by Pierce topological structure；The FBAR is the detecting element in acoustic wave sensor gauge outfit, for detecting Extraneous measured physical quantity；Frequency detection circuit includes six-port network, four energy meters and standard termination, BAW agitators it is defeated Exit port is connected with the port one of six-port network, and standard termination is connected with the port two of six-port network, four power score It is not connected with other four ports of six-port network.

Radio-frequency signal generator of the BAW agitators as frequency detection circuit, for providing for frequency detection circuit Radio-frequency input signals.

The FBAR both as the detecting element in acoustic wave sensor gauge outfit, and as the primary element of BAW agitators. FBAR perceives the change of measured physical quantity, and external physical quantity change causes the resonant frequency of FBAR to change, while also causing BAW to shake The frequency of oscillation for swinging device changes, and the two changes are equal.

The FBAR can be any FBAR structures, including through hole type, air gap type and solid-state assembly type structure.

The BAW agitators are to connect above-mentioned FBAR, transistor and lamped element by Pierce topological structure modes Constitute BAW agitators.This is the characteristics of perception is presented between series and parallel resonant frequency according to FBAR, will be FBAR electric with two Hold C1, C2 constitutes the basic reactance component of BAW agitators, meet the oscillating condition that the total reactance in loop is zero, four resistance R1, The direct current biasing of R2, Re, Rc for needed for the transistor offer work of BAW agitators, inductance L1 prevent high-frequency signal interference direct current Power supply, inductance L2 prevent high-frequency signal to ground, and coupled capacitor Cb is for feedback signal to be coupled to the input of BAW agitators.

It can also be field effect transistor that the transistor can be audion, and effect is to provide required negative resistance for agitator.

For frequency detection circuit is further depicted as：

The frequency detection circuit is the core component of acoustic wave sensor reading circuit, in the port of six-port network, Input port of the port of connection BAW agitators for radiofrequency signal, when six ports of six-port network connect BAW vibrations respectively When device, standard termination, four energy meters, a kind of acoustic wave sensor reading circuit is just constituted；Substantially the original of the reading circuit Reason is：BAW agitators provide radiofrequency signal for six-port network, obtain four power readings by four energy meter measurements, will The systematic parameter of this four power readings and six-port network substitutes into computing formula, can be calculated and be connected with six-port network Standard termination reflection coefficient, computing formula is：

WhereinFor reflection coefficient（Plural number, it is unknown）,、、WithFor energy meter reading（Real number, it is known that）,、、、、WithFor the systematic parameter of six-port network（Change with frequency, it is known that）.

Frequency detection circuit needs calibration using front.Calibration steps is：The port one of six-port network is connected to radio frequency source Outfan, port two changes different standard terminations, and often changing a standard termination carries out a sweep measurement, standard termination More than or equal to four, the effect of standard termination is to provide known reflection coefficient to number, finally reads different frequency corresponding energy meter Number and reflection coefficient substitute into the reflection coefficient of six ports and calculate formula, try to achieve systematic parameter, so as to the calibration of completion system parameter.

Can be known with frequency change by the systematic parameter in above formula, when BAW agitators provide different frequency for six-port network Radiofrequency signal when, energy meter obtain power reading be different from.When BAW oscillator frequencies are a certain frequency fm（fp<fm< fq）When, power reading is, it is known that as fm is unknown, therefore the corresponding systematic parameters of fm are unknown, but systematic parameter-frequency curve is Know, if by fm corresponding power reading and other a certain frequency fn（fp<fm<Fq, fn ≠ fm）Corresponding systematic parameter is substituted into In above formula, a reflection coefficient can be obtained, but the reflection coefficient that obtains is neither the corresponding reflection coefficient of fm is nor fn correspondences Reflection coefficient, it is therefore meaningless, be called false reflection coefficient.Thus, if by fm corresponding power reading successively with（（fp, fq）The corresponding systematic parameter of frequency in scope is updated in above formula, can be calculated（fp,fq）In the range of false reflection coefficient- Frequency curve, but as power reading is obtained at fm, so false reflection coefficient-frequency curve only corresponding reflection at fm Coefficient is correct.

Frequency of oscillation to obtain the BAW agitators of a certain unknown frequency, the frequency of its acoustic wave sensor resolve electricity Line structure can be：The output port of BAW agitators is connected with the port one of six-port network, the port two of six-port network One standard termination of connection（Known to the reflection coefficient-frequency curve of standard termination）, remaining four ports of six-port network It is connected with four energy meters respectively.Then four power readings are obtained by the four of six-port network energy meters（BAW agitators The corresponding power reading of frequency of oscillation）, and by power reading and a certain frequency band（Comprising BAW agitator frequencies of oscillation）Interior frequency The corresponding systematic parameter of rate is updated in above formula, can calculate a false reflection coefficient-frequency of the standard termination in the frequency band Curve.From the foregoing, it will be observed that reflection coefficient is only known in the unknown frequency point, therefore by false reflection coefficient-frequency curve and mark Reflection coefficient-the frequency curve of quasi- load is contrasted, and can obtain unique intersection point, and the corresponding frequency of the intersection point is BAW agitators Frequency of oscillation.

For being further depicted as standard termination：

Described standard termination can be matched load, short-circuiting device, open circuit device and arbitrary load known to reflection coefficient, its mesh Be to provide reflection coefficient known to a group as comparison value for a kind of acoustic wave sensor reading circuit, in order to only measure BAW agitator frequencies of oscillation are calculated in the case of single-frequency point reflection coefficient.

For being further depicted as energy meter：

Described energy meter is energy meter of the operating frequency in radio frequency band, can be real by Schottky diode cymoscope etc. Existing, this is that the critical component that radiofrequency signal direct frequency reducing is fundamental frequency, this utility model can be needed four by frequency detection circuit Energy meter, and four energy meters must have good concordance.

The beneficial effects of the utility model are as follows：

This utility model is while realizing that BAW oscillator frequencies are detected, moreover it can be used to BAW sensor reading circuit, and The characteristics of with simple structure, easy of integration and high real-time, contribute to the miniaturization of BAW sensor；This utility model can meet The application demand of the fields such as Aero-Space, Weapons Engineering, the automobile BAW sensor good to high sensitivity, manufacturability.

Description of the drawings

Fig. 1 is schematic diagram of the present utility model；

Fig. 2 is the schematic diagram of six-port reflectometer of the present utility model；

Fig. 3 is a kind of schematic diagram of embodiment that this utility model medium frequency detects circuit；

Fig. 4 is flow chart of the present utility model；

Fig. 5 is simulation result schematic diagram of the present utility model；

Fig. 6 is a kind of schematic diagram of embodiment of energy meter in this utility model；

Fig. 7 is the schematic diagram of six-port network of the present utility model；

Fig. 8 is calibration figure of the present utility model.

Wherein, reference is：1-FBAR, 2- transistor, 3- DC sources, 4- L1 inductance, 5-Rc resistance, 6- R1 are electric Resistance, 7-Cb electric capacity, 8- R2 resistance, 9-Re resistance, 10-L2 inductance, 11- C1 electric capacity, 12- C2 electric capacity, 13- six-port networks, 14- P1 energy meters, 15- P2 energy meters, 16- P3 energy meters, 17- P4 energy meters, 18- standard terminations, 19-BAW agitators, 20- frequency detection circuits, 21- orthogonal mixers, 22- radio-frequency signal generators, 23- six-port reflectometers, 24- six-port networks Port one, 25- six-port networks port two, 26- six-port networks port three, 27- six-port networks port four, six ports of 28- The network port five, 29- six-port networks port six.

Specific embodiment

Below in conjunction with the accompanying drawings this utility model is elaborated：

As shown in figure 1, a kind of new acoustic wave sensor reading circuit, including BAW agitators 19 and frequency detection circuit 20。

The BAW agitators 19 are by FBAR 1, transistor 2, DC source 3, L1 inductance 4, Rc resistance 5, R1 resistance 6, Cb Electric capacity 7, R2 resistance 8, Re resistance 9, L2 inductance 10, C1 electric capacity 11 and C2 electric capacity 12 are constituted；Frequency detection circuit 20 is by six ports Network 13, P1 energy meters 14, P2 energy meters 15, P3 energy meters 16, P4 energy meters 17 and standard termination 18 are constituted.

Wherein：FBAR 1, C1 electric capacity 11 and C2 electric capacity 12 have connected and composed the basic reactance component of BAW agitators 19, full The total reactance in sufficient loop is zero oscillating condition；Rc resistance 5, R1 resistance 6, R2 resistance 8 and Re resistance 9 are provided directly for transistor 2 Used by stream bias voltage；L1 inductance 4 is that L2 inductance 10 is to prevent high frequency in order to prevent high-frequency signal interference DC source 3 Signal directly arrives ground；Cb electric capacity 7 is for the input that feedback signal is coupled to BAW agitators 19 for coupled capacitor；Six ends Mouthful network 13 is the key of 20 interferometric principle of frequency detection circuit, is illustrated in figure 7 the schematic diagram of six-port network, six The radiofrequency signal and the reflected signal of standard termination 18 that BAW agitators 19 can be provided by port network 13 is passed according to certain ratio It is defeated to other four ports；Measurement of reflection-factor object of the standard termination 18 for frequency detection circuit 20；P1 energy meters 14, P2 work( Rate meter 15, P3 energy meters 16, P4 energy meters 17 are that radiofrequency signal directly can be dropped in frequency detection circuit 20 fundamental frequency frequency The critical component of band, can provide four power readings for frequency detection circuit, so as to reach the calculating necessary requirement of reflection coefficient. Frequency detection circuit 20 is obtained from 23 block diagram of the six-port reflectometer change shown in Fig. 2, and frequency detection circuit 20 is by six ends The radio-frequency signal generator 22 of the connection of port 1 of oral reflex meter 23 is deleted, and connects a standard termination on port 2 25 18, remaining port 26-29 still connect P1 energy meters 14, P2 energy meters 15, P3 energy meters 16, P4 energy meters 17 and obtain.

Specifically it is connected as：The C1 electric capacity 11 and C2 electric capacity 12 constitute the basic reactance component of BAW agitators 19； R1 One end of resistance 6, R2 resistance 8 and Cb electric capacity 7 is connected to the base stage of transistor 2, and 6 other end of R1 resistance is connected to FBAR1, R2 The other end ground connection of resistance 8, the other end ground connection of Cb electric capacity 7；L1 inductance 4, Rc resistance 5 are series at DC source 3 and transistor 2 Colelctor electrode between；Ground is directly arrived in one end of L2 inductance 10, and the other end of L2 inductance 10 connects Re resistance 9, and Re resistance 9 is connected to The emitter stage of transistor 2.

One end of C1 electric capacity 11 is connected to colelctor electrode and the six-port network port 1 of transistor 2, C1 electric capacity 11 simultaneously The other end be connected with the emitter stage and C2 electric capacity 12 of transistor 2.

The outfan of P1 energy meters 14, P2 energy meters 15, P3 energy meters 16 and P4 energy meters 17 is grounded.

One end of standard termination 18 is connected to the port 2 25 of six-port network 13, other end ground connection.

One end of the FBAR1 is connected with R1 resistance 6, other end ground connection.

For said frequencies detect circuit 20, before its use, calibration, flow process such as Fig. 8 institutes of its calibration steps are needed Show：The port 1 of six-port network 13 is connected to the outfan of radio frequency source, and port 2 25 is changed different standard terminations, often changes one Individual standard termination carries out a sweep measurement, and number n of standard termination is more than or equal to four, according to Hoer methods or relative power method Calibrate, then n=4；According to other calibration steps, then n>4.The effect of standard termination is to provide known reflection coefficient, finally will The corresponding energy meter reading of different frequency and reflection coefficient substitute into the reflection coefficient of six ports and calculate formula, try to achieve systematic parameter, So as to the calibration of completion system parameter.

As shown in figure 3, a kind of specific embodiment of the frequency detection circuit 20, the six-port network 13 in figure is adopted Realized with the mode of microstrip line, and the structure of six-port network 13 is formed by connecting using four orthogonal mixers 21, its Simple structure and can equivalency transform be that CMOS technology is realized by way of lamped element so that a kind of acoustic wave sensor reads The characteristics of circuit has easy of integration.

By the BAW agitators of 1.5 GHz and as a example by standard termination selection matched load, according to a kind of body sound shown in Fig. 4 Wave sensor reading circuit flow process, emulation obtain result as shown in Figure 5.As can be seen from Figure 5 false reflection coefficient-frequency is bent Line has unique intersection point with reference to reflection coefficient-frequency curve, and the frequency corresponding to intersection point is 1.5 GHz.

Fig. 6 is the specific embodiment of the energy meter, selects suitable cymoscope chip to constitute with lumped-parameter element Energy meter, it becomes possible to meet the measurement requirement of four power output ports of frequency detection circuit.

Claims (5)

1. a kind of acoustic wave sensor reading circuit, it is characterised in that：Including BAW agitators（19）And frequency detection circuit （20）；BAW agitators（19）Including FBAR FBAR（1）With other basic circuit elements, film bulk acoustic is humorous Shake device FBAR（1）It is attached by Pierce topological structure with other basic circuit elements；The frequency detection circuit（20） Including six-port network（13）, four energy meter and standard terminations（18）, BAW agitators（19）Output port and six port nets Network（13）Port one（24）Connection, standard termination（18）With six-port network（13）Port two（25）Connection, four power Meter includes P1 energy meters（14）, P2 energy meters（15）, P3 energy meters（16）With P4 energy meters（17）, four energy meters are respectively with six Port network（13）The connection of remaining four ports.

2. a kind of acoustic wave sensor reading circuit according to claim 1, it is characterised in that：Described other primary elements Including transistor（2）, DC source（3）, L1 inductance（4）, Rc resistance（5）, R1 resistance（6）, Cb electric capacity（7）, R2 resistance（8）、 Re resistance（9）, L2 inductance（10）, C1 electric capacity（11）With C2 electric capacity（12）；The C1 electric capacity（11）With C2 electric capacity（12）Constitute BAW agitators（19）Basic reactance component；C1 electric capacity（11）One end be simultaneously connected to transistor（2）Colelctor electrode and six ends The mouth network port one（24）, C1 electric capacity（11）The other end and transistor（2）Emitter stage and C2 electric capacity（12）Connection；R1 is electric Resistance（6）, R2 resistance（8）With Cb electric capacity（7）One end be connected to transistor（2）Base stage, R1 resistance（6）The other end is connected to FBAR FBAR（1）, R2 resistance（8）The other end ground connection, Cb electric capacity（7）The other end ground connection；L1 inductance （4）, Rc resistance（5）It is series at DC source（3）And transistor（2）Colelctor electrode between；L2 inductance（10）One end directly arrive Ground, L2 inductance（10）The other end connection Re resistance（9）, Re resistance（9）It is connected to transistor（2）Emitter stage.

3. a kind of acoustic wave sensor reading circuit according to claim 1, it is characterised in that：The frequency detection circuit （20）In P1 energy meters（14）, P2 energy meters（15）, P3 energy meters（16）With P4 energy meters（17）Outfan be grounded；Mark Quasi- load（18）One end be connected to six-port network（13）Port two（25）, other end ground connection.

4. a kind of acoustic wave sensor reading circuit according to claim 1, it is characterised in that：The frequency detection circuit （20）Systematic parameter calibration circuit structure be：Six-port network（13）Port one（24）The outfan of radio frequency source is connected to, Six-port network（13）Port two（25）The standard termination of the different impedances of connection（18）；The number of standard termination is no less than four It is individual；The six-port network（13）Port two（25）Often connect a standard termination（18）Frequency sweep of correspondence；Six port nets Network（13）Remaining four ports be connected with four energy meters respectively.

5. a kind of acoustic wave sensor reading circuit according to claim 1, it is characterised in that：The frequency of acoustic wave sensor Rate resolving circuit structure is：Six-port network（13）Port one（24）It is connected to the outfan of radio frequency source, six-port network（13） Port two（25）One standard termination of connection（18）, four energy meters respectively with six-port network（13）It is remaining four end Mouth connection.