CN205880061U - Little electric capacity reference measuring circuit with multrirange - Google Patents
Little electric capacity reference measuring circuit with multrirange Download PDFInfo
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- CN205880061U CN205880061U CN201620615022.3U CN201620615022U CN205880061U CN 205880061 U CN205880061 U CN 205880061U CN 201620615022 U CN201620615022 U CN 201620615022U CN 205880061 U CN205880061 U CN 205880061U
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Abstract
The utility model discloses a little electric capacity reference measuring circuit with multrirange, it is surveyed condenser network and a plurality of reference capacitance measurement circuit to include. Excitation voltage signal from then on common port inserts the measuring circuit, its operational amplifier and feedback circuit who corresponds of the current conveyance of each electric capacity converts respective voltage signal into, and then measure the quilt and survey the capacitance that the output voltage ratio of condenser network and a certain reference measuring circuit obtained being surveyed electric capacity, from this through setting up reference electric capacity into different capacitances and controlling the feedback circuit who is corresponded by the survey condenser network and realize a plurality of measurement ranges, thereby the measuring range of little electric capacity reference measuring circuit has been expanded, the reference electric capacity of the difference that sets up through the multrirange and the comparison of being surveyed the electric capacity structure, the precision of being surveyed electric capacity has been improved. This circuit is applied to in analog integrated circuit test system, digital integrated circuit test system, hybrid integrated circuit test system and the discrete semiconductor device test system.
Description
Technical field
This utility model belongs to basic electronic surveying field, is specifically related to one and has multiple range micro-electric capacity reference measurement
Circuit and method.
Background technology
ESD protection chip or its assembly can be that the semiconductor device in circuit provides electrostatic discharge (ESD) protection and other overvoltage
Protection, prevents defective semiconductor devices.Parasitic capacitance is an important parameter of ESD protection chip, therefore in volume production, needs to survey
The parasitic capacitance (generally in pF magnitude) of examination ESD protection chip.For the test of parasitic capacitance, some Chevron Research Company (CRC)s or encapsulation
Testing factory selects LCR table, but the cost of LCR table is of a relatively high.In view of cost factor, it is special micro-that people devise some
Capacitance measurement circuit.The principle of these special measurement circuit is also not quite similar, at patent of invention (publication number CN101349716A)
And document " the micro-capacitance measuring instrument amplified based on reference electric capacity and locking " is proposed micro-capacitance reference measuring circuit.
In the micro-capacitance reference measuring circuit proposed in described patent and document, the capacitance of reference electric capacity and measured capacitance
Capacitance closer to, the accuracy of measurement is the highest.Different ESD protection chips, the numerical value of its parasitic capacitance is also not quite similar,
If the numerical value of parasitic capacitance of some the ESD protection chips numerical value of parasitic capacitance less than 1pF, some ESD protection chips is several
Ten pF are the highest, but described micro-capacitance reference measuring circuit only one of which measure range, therefore for from less than 1pF to several
The measurement scope of the ten the most hundreds of pF of pF, single described capacitance measurement circuit cannot ensure higher in the range of described measurement
Certainty of measurement.And then in actual volume production, people need multiple described micro-capacitance reference measuring circuit for testing ESD protection core
The parasitic capacitance parameter of sheet, but multiple measuring circuit is unfavorable for the management of actual volume production, adds volume production link mistake and uses
The probability of described measuring circuit.
Summary of the invention
The purpose of this utility model is to propose one to have multiple range micro-capacitance reference measuring circuit and method, by increasing
Add branch road and arranging of switch realizes multiple range measurement, and the different reference electric capacity arranged by multrirange is with tested
The comparison of capacitance structure, improves the precision of measured capacitance.
To achieve these goals, the technical solution of the utility model is:
There is multiple range micro-capacitance reference measuring circuit, wherein, described multiple range micro-capacitance reference measuring circuit bag
Including multichannel reference capacitance test circuit and a road measured capacitance test circuit, described reference capacitance test circuit is by operation amplifier
Device, reference electric capacity and feedback impedance composition, the capacitance of multichannel reference electric capacity is different, and one end of reference electric capacity is connected to fortune
Calculating the inverting input of amplifier, the in-phase input end of operational amplifier is connected to ground, and feedback impedance is connected across operational amplifier
Between inverting input and operational amplifier output terminal；Described measured capacitance test circuit includes operational amplifier, measured capacitance
And the feedback impedance identical with multichannel reference capacitance test circuit way and multipath control switch, one end of measured capacitance is even
Being connected on the inverting input of operational amplifier, the in-phase input end of operational amplifier is connected to ground, feedback impedance and control switch
Connecting and be connected across between operational amplifier inverting input and operational amplifier output terminal, a driving voltage signal is simultaneously with many
LUSHEN connects than the electric capacity other end and the measured capacitance other end, tension measuring circuit selective the most respectively with multichannel reference
The outfan of the output of capacitance test circuit and measured capacitance test circuit connects.
Scheme is further: described multipath control switch connects the first multiplexer circuit, and described tension measuring circuit leads to
Crossing the second multiplexer circuit to be connected with the outfan of reference capacitance test circuit, described tension measuring circuit passes through the 3rd multichannel
The outfan of selection circuit and measured capacitance test circuit is connected, the first multiplexer circuit, the second multiplexer circuit, the 3rd
Multiplexer circuit accepts the I/O Interface Controller of a microprocessor respectively.
Scheme is further: the multiple feedback impedance in described multichannel reference capacitance test circuit is resistance, described tested
The feedback impedance of capacitance test circuit is resistance, and multichannel reference electric capacity is the different reference capacitances between 1pF to 1000pF.
Scheme is further: described measured capacitance test circuit control switch by the first switch and second switch in parallel
Composition, first switch be connected between tension measuring circuit and feedback resistance, second switch be connected to operational amplifier output with
Between feedback resistance.
Scheme is further: the multiple feedback impedance in described multichannel reference capacitance test circuit be resistance and electric capacity in parallel
Capacitance-resistance impedance, the feedback impedance of described measured capacitance test circuit is a resistance and the capacitance-resistance impedance of multichannel electric capacity parallel connection, one
Individual resistance is connected across between operational amplifier inverting input and operational amplifier output terminal, and described multichannel electric capacity concatenates one respectively
Individual described control switch is connected across between operational amplifier inverting input and operational amplifier output terminal.
Scheme is further: the control switch of described measured capacitance test circuit is made up of the first switch and second switch,
First switch is connected between tension measuring circuit and feedback capacity, and second switch is connected to operational amplifier output and feedback electricity
Between appearance.
Scheme is further: the multiple feedback impedance Zhong mono-road feedback impedance of described measured capacitance test circuit and selection
In corresponding multichannel reference capacitance test circuit, the resistance value of the feedback impedance on a road is identical.
Scheme is further: the feedback impedance value of described multichannel reference capacitance test circuit is identical, and described measured capacitance is surveyed
In examination circuit, multiple feedback resistance value is identical.
This utility model is by increasing reference measurement branch road and by the reference electric capacity in multiple reference condenser network branch roads
Capacitance be configured to different numerical value and increase the feedback branch corresponding to measured capacitance circuit and feedback branch can pass through
Switch carries out selecting control, and then can control the current ratio flowing through measured capacitance with reference electric capacity in same measuring circuit
Value, solves the problem that prior art only has single-measurement range, it is simple in practicality, the capacitance according to measured capacitance is certainly
Dynamic select to measure range, beneficially production management reduce mistake and use the probability of measuring circuit, arranged by multrirange meanwhile
Different reference electric capacity and the comparison of measured capacitance structure, improve the precision of measured capacitance.
With embodiment, this utility model is described in detail below in conjunction with the accompanying drawings.
Accompanying drawing explanation
Fig. 1 be resistance feedback there is multiple range micro-capacitance reference measuring circuit；
Fig. 2 be capacitive feedback there is multiple range micro-capacitance reference measuring circuit.
Detailed description of the invention
There is multiple range micro-capacitance reference measuring circuit, wherein, described multiple range micro-capacitance reference measuring circuit bag
Including multichannel reference capacitance test circuit and a road measured capacitance test circuit, described reference capacitance test circuit is by operation amplifier
Device, reference electric capacity and feedback impedance composition, the capacitance of multichannel reference electric capacity is different, and one end of reference electric capacity is connected to fortune
Calculating the inverting input of amplifier, the in-phase input end of operational amplifier is connected to ground (being equivalent to power cathode), feedback impedance
It is connected across between operational amplifier inverting input and operational amplifier output terminal；Described measured capacitance test circuit includes computing
Amplifier, measured capacitance and the feedback impedance identical with multichannel reference capacitance test circuit way and multipath control switch, quilt
The one end surveying electric capacity is connected to the inverting input of operational amplifier, and the in-phase input end of operational amplifier is connected to ground (quite
In power cathode), feedback impedance is connected across operational amplifier inverting input and operational amplifier output with controlling to switch to be connected
Between end, a driving voltage signal is connected with the multichannel reference electric capacity other end and the measured capacitance other end simultaneously, an electricity
Pressure measuring circuit selective the most respectively with output and the output of measured capacitance test circuit of multichannel reference capacitance test circuit
End connects.
In embodiment: described multipath control switch therein can be hand switch, as one automatically control preferred
Scheme, described multipath control switch connects the first multiplexer circuit, and described tension measuring circuit is by the second multi-path choice electricity
Road is connected with the outfan of reference capacitance test circuit, and described tension measuring circuit is by the 3rd multiplexer circuit and tested electricity
The outfan holding test circuit connects, and the first multiplexer circuit, the second multiplexer circuit, the 3rd multiplexer circuit are respectively
Accept the I/O Interface Controller of a microprocessor；It is selective respectively with many that tension measuring circuit born by microprocessor simultaneously
LUSHEN connects, to output voltage according to setting than the output of capacitance test circuit and the outfan of measured capacitance test circuit
The work that step is measured, calculated.
Two kinds of preferred versions are had as multichannel reference capacitance test circuit:
The first: as it is shown in figure 1, the multiple feedback impedance in described multichannel reference capacitance test circuit is resistance, described
The feedback impedance of measured capacitance test circuit is resistance, and multichannel reference electric capacity is the different reference electric capacity between 1pF to 1000pF
Value.
Wherein, because test is trace electric capacity, in order to overcome the feedback current circuit impact on measuring voltage in measurement,
Voltage test points is avoided the circuit that feedback current flows through, therefore: the control of described measured capacitance test circuit switchs by parallel connection
The first switch and second switch form, the first switch is connected between tension measuring circuit and feedback resistance, and second switch is even
It is connected between operational amplifier output and feedback resistance.
It two is: as shown in Figure 2: the multiple feedback impedance in described multichannel reference capacitance test circuit is resistance and electric capacity
Capacitance-resistance impedance in parallel, the feedback impedance of described measured capacitance test circuit is the capacitance-resistance resistance of a resistance and the parallel connection of multichannel electric capacity
Anti-, a resistance is connected across between operational amplifier inverting input and operational amplifier output terminal, and described multichannel electric capacity is respectively
Concatenate a described control switch to be connected across between operational amplifier inverting input and operational amplifier output terminal.
In like manner, because test is trace electric capacity, in order to overcome the feedback current circuit impact on measuring voltage in measurement,
Voltage test points is avoided the circuit that feedback current flows through, therefore: the control of described measured capacitance test circuit switchs by first
Switch and second switch form, and the first switch is connected between tension measuring circuit and feedback capacity, and second switch is connected to fortune
Calculate between amplifier output and feedback capacity.
Finally calculating (introducing below) by the parameter after measuring and go out measured capacitance values, formula therein uses known ginseng
Number, therefore to simplified operation:
1, the multiple feedback impedance Zhong mono-road feedback impedance of described measured capacitance test circuit and multichannel corresponding to selection
In reference capacitance test circuit, the resistance value of the feedback impedance on a road is identical.
2, the feedback impedance value of described multichannel reference capacitance test circuit is identical, multichannel in described measured capacitance test circuit
Feedback impedance value is identical.
There is the measuring method of multiple range micro-capacitance reference measuring circuit, described multiple range micro-electric capacity reference measurement electricity
Road includes multichannel reference capacitance test circuit and a road measured capacitance test circuit, and described reference capacitance test circuit is put by computing
Big device, reference electric capacity and feedback resistance composition, the capacitance of multichannel reference electric capacity is different, and one end of reference electric capacity is connected to
The inverting input of operational amplifier, the in-phase input end of operational amplifier is connected to ground (being equivalent to power cathode), feedback electricity
Resistance is connected across between operational amplifier inverting input and operational amplifier output terminal；Described measured capacitance test circuit is by computing
Amplifier, measured capacitance and the feedback resistance identical with multichannel reference capacitance test circuit way and multipath control switch group
Becoming, one end of measured capacitance is connected to the inverting input of operational amplifier, and the in-phase input end of operational amplifier is connected to ground
(being equivalent to power cathode), feedback resistance is connected with control switch and is connected across operational amplifier inverting input and operational amplifier
Between outfan, tension measuring circuit selective the most respectively with output and the tested electricity of multichannel reference capacitance test circuit
The outfan holding test circuit connects；Wherein, the described switch that controls is made up of the first switch in parallel and second switch, and first opens
Pass is connected between tension measuring circuit and feedback resistance, second switch be connected to operational amplifier output with feedback resistance it
Between；Described method is: a driving voltage signal is concurrently accessed the multichannel reference electric capacity other end and the measured capacitance other end；
Wherein: first, the capacitance of anticipation measured capacitance, measured capacitance is tested the first switch of multichannel resistance in circuit
Disconnect with second switch, then,
Step 1, select and measure with judge capacitance closest to a LUSHEN than the output voltage values of capacitance test circuit, connect
, select the second switch Guan Bi that measured capacitance test circuit Zhong Yu mono-road electricity group connects, operational amplifier output and feedback electricity
Resistance is connected, and then, closes first switch in parallel with second switch and accesses tension measuring circuit measurement measured capacitance test circuit
Output voltage values, then calculate measured capacitance values according to known parameters and formula；
Step 2, it is judged that: when the measured capacitance values calculated is closest to a LUSHEN than capacitance, then measured capacitance values is
Final measured capacitance values；When the measured capacitance values calculated is not closest to a LUSHEN than capacitance, then repeat step 1.
Actual measurement is 1pF or during less than 1pF when measured capacitance, as the load measuring environment, i.e. measured capacitance
The parasitic capacitance of body (such as connecting interface) cannot be ignored, and the proportion shared by parasitic capacitance is the biggest, therefore, when tested electricity
Appearance be 1pF or less than 1pF time, described method farther include detect parasitic capacitance step: remove measured capacitance, detect tested
The parasitic capacitance of electric capacity carrier, described tested capacitance is the capacitance that the capacitance detected for the first time deducts parasitic capacitance.
Embodiment 3:
There is the measuring method of multiple range micro-capacitance reference measuring circuit, described multiple range micro-electric capacity reference measurement electricity
Road includes multichannel reference capacitance test circuit and a road measured capacitance test circuit, and described reference capacitance test circuit is put by computing
The feedback capacitance-resistance impedance composition of big device, reference electric capacity and resistance and electric capacity parallel connection, each the most not phase of the capacitance of multichannel reference electric capacity
With, one end of reference electric capacity is connected to the inverting input of operational amplifier, and the in-phase input end of operational amplifier is connected to ground
(being equivalent to power cathode), feedback capacitance-resistance impedance be connected across operational amplifier inverting input and operational amplifier output terminal it
Between；Described measured capacitance test circuit is by operational amplifier, measured capacitance and identical with multichannel reference capacitance test circuit way
Feedback resistance and multipath control switch composition, one end of measured capacitance is connected to the inverting input of operational amplifier, fortune
The in-phase input end calculating amplifier is connected to ground (being equivalent to power cathode), wherein: described feedback impedance is that a resistance is with many
The capacitance-resistance impedance that road feedback capacity is in parallel, a resistance is connected across operational amplifier inverting input and operational amplifier output terminal
Between, described multiple feedback electric capacity concatenates a described control switch respectively and is connected across operational amplifier inverting input and computing
Between amplifier out, tension measuring circuit selective the most respectively with the output of multichannel reference capacitance test circuit and
The outfan of measured capacitance test circuit connects；Wherein, the described switch that controls is made up of the first switch in parallel and second switch,
First switch is connected between tension measuring circuit and feedback capacity, and second switch is connected to operational amplifier output and feedback electricity
Between appearance；Described method is: driving voltage signal be concurrently accessed the multichannel reference electric capacity other end and measured capacitance another
End；
Wherein: first, the capacitance of anticipation measured capacitance, measured capacitance is tested the first switch of multichannel resistance in circuit
Disconnect with second switch, then,
Step 1, select and measure with judge capacitance closest to a LUSHEN than the output voltage values of capacitance test circuit, connect
, select the second switch Guan Bi that measured capacitance test circuit Zhong Yu mono-tunnel feedback capacity connects, operational amplifier output is with anti-
Feed holds to be connected, and then, closes the first switch access tension measuring circuit in parallel with second switch and measures measured capacitance test
The output voltage values of circuit, then calculates measured capacitance values according to known parameters and formula；
Step 2, it is judged that: when the measured capacitance values calculated is closest to a LUSHEN than capacitance, then measured capacitance values is
Final measured capacitance values；When the measured capacitance values calculated is not closest to a LUSHEN than capacitance, then repeat step 1.
In like manner: be 1pF or during less than 1pF when measured capacitance in actual measurement, as measuring environment, i.e. measured capacitance
The parasitic capacitance of carrier (such as connecting interface) cannot ignore, the proportion shared by parasitic capacitance is the biggest, therefore, works as quilt
Survey electric capacity be 1pF or less than 1pF time, described method farther include detect parasitic capacitance step: remove measured capacitance, detection
The parasitic capacitance of measured capacitance carrier, described tested capacitance is the electric capacity that the capacitance detected for the first time deducts parasitic capacitance
Value.
Specifically introduce below by accompanying drawing above-described embodiment realize process:
One, resistance feedback there is multiple range micro-capacitance reference measuring circuit.
As it is shown in figure 1, the technical scheme that this embodiment is given has three reference condenser network branch roads and a tested electricity
Capacitive circuit, wherein VinFor driving voltage signal, Cr1、Cr2、Cr3Different for reference electric capacity and capacitance, CxFor measured capacitance, described
Reference electric capacity Cr1、Cr2、Cr3It is connected with one end of described measured capacitance Cx, described driving voltage signal VinAccess from this common port
Measuring circuit.
Described reference electric capacity Cr1、Cr2、Cr3The most corresponding operational amplifier N1, N2, N3, and Cr1、Cr2、Cr3The other end
It is respectively connected to the reverse input end of described operational amplifier N1, N2, N3.The in-phase input end of described operational amplifier N1, N2, N3
Ground connection, is connected to feedback resistance R between reverse input end and the outfan of operational amplifier N1, N2, N3f1、Rf2、Rf3, fortune
Calculate the output voltage signal V of the most corresponding three the reference condenser network branch roads of output of amplifier N1, N2, N3cr1、Vcr2、Vcr3。
Described measured capacitance CxCorresponding operational amplifier N4 and CxThe other end access described operational amplifier N4 reverse
Input.The in-phase input end ground connection of described operational amplifier N4；Between reverse input end and the outfan of operational amplifier N4
Being connected in parallel to three feedback branches, wherein the first feedback branch 101 has feedback resistance Rf4With switch being connected in series of S1B, the
Two feedback branches 102 have feedback resistance Rf5With switch being connected in series of S2B, the 3rd feedback branch 103 has feedback resistance Rf6With open
Close being connected in series of S3B.
For described feedback resistance Rf4, its one end being connected with described switch S1B is connected with one end of switch S1A；Right
In described feedback resistance Rf5, its one end being connected with described switch S2B is connected with one end of switch S2A；For described feedback
Resistance Rf6, its one end being connected with described switch S3B is connected with one end of switch S3A；And then by described switch S1A, S2A and
The other end of S3A is connected, and draws the output voltage signal V of described measured capacitance circuit from this common portcx。
The work process of the embodiment shown in Fig. 1 is as follows:
The feedback branch arranging operational amplifier N4 corresponding to described measured capacitance circuit is described first feedback branch
101, the most described switch S1B connect, described switch S2B and S3B disconnects, the most described driving voltage signal VinPut on described
Reference electric capacity Cr1、Cr2、Cr3And described measured capacitance CxAfter, described reference electric capacity Cr1、Cr2、Cr3And described measured capacitance Cx
Electric current respectively with flow through described feedback resistance Rf1、Rf2、Rf3And Rf4Electric current identical, and this electric current flow back into institute respectively
State the outfan of operational amplifier N1, N2, N3 and N4, and then the output voltage V of described operational amplifier N1, N2, N3cr1、
Vcr2、Vcr3Respectively equal to described feedback resistance Rf1、Rf2、Rf3Voltage；Described switch S1A connects, described switch S2A and S3A
Disconnect, and then obtain described feedback resistance Rf4Voltage, this voltage is equal to the output voltage V of described measured capacitance circuitcx.By
This can obtain:
Formula 1
Formula 2
Formula 3
Formula 4
Formula 5
Formula 6
Formula 7
The feedback branch arranging operational amplifier N4 corresponding to described measured capacitance circuit is described second feedback branch
102, the most described switch S2B connect, described switch S1B and S3B disconnects, the most described driving voltage signal VinPut on described
Reference electric capacity Cr1、Cr2、Cr3And described measured capacitance CxAfter, described reference electric capacity Cr1、Cr2、Cr3And described measured capacitance Cx
Electric current respectively with flow through described feedback resistance Rf1、Rf2、Rf3And Rf5Electric current identical, and this electric current flow back into institute respectively
State the outfan of operational amplifier N1, N2, N3 and N4, and then the output voltage V of described operational amplifier N1, N2, N3cr1、
Vcr2、Vcr3Respectively equal to described feedback resistance Rf1、Rf2、Rf3Voltage；Described switch S2A connects, described switch S1A and S3A
Disconnect, and then obtain described feedback resistance Rf5Voltage, this voltage is equal to the output voltage V of described measured capacitance circuitcx.By
This can obtain:
Formula 8
Formula 9
Formula 10
Formula 11
The feedback branch arranging operational amplifier N4 corresponding to described measured capacitance circuit is described 3rd feedback branch
103, the most described switch S3B connect, described switch S1B and S2B disconnects, the most described driving voltage signal VinPut on described
Reference electric capacity Cr1、Cr2、Cr3And described measured capacitance CxAfter, described reference electric capacity Cr1、Cr2、Cr3And described measured capacitance Cx
Electric current respectively with flow through described feedback resistance Rf1、Rf2、Rf3And Rf6Electric current identical, and this electric current flow back into institute respectively
State the outfan of operational amplifier N1, N2, N3 and N4, and then the output voltage V of described operational amplifier N1, N2, N3cr1、
Vcr2、Vcr3Respectively equal to described feedback resistance Rf1、Rf2、Rf3Voltage；Described switch S3A connects, described switch S1A and S2A
Disconnect, and then obtain described feedback resistance Rf6Voltage, this voltage is equal to the output voltage V of described measured capacitance circuitcx.By
This can obtain:
Formula 12
Formula 13
Formula 14
Formula 15
C in described equation formula 5, formula 6, formula 7, formula 9, formula 10, formula 11, formula 13, formula 14, formula 15r1、Cr2And Cr3Use respectively
In representing described reference electric capacity Cr1、Cr2And Cr3Capacitance, owing to the capacitance of described reference electric capacity is different, therefore these etc.
C in formular1、Cr2And Cr3For different numerical value.
By the feedback resistance R in described first feedback branch 101f4, feedback resistance in described second feedback branch 102
Rf5, feedback resistance R in described 3rd feedback branch 103f6Resistance value be set to different numerical value, and then described equation formula
5, the R in formula 6, formula 7, formula 9, formula 10, formula 11, formula 13, formula 14, formula 15f4、Rf5And Rf6For different numerical value.
By the operation amplifier that the different described reference capacitance measurement branch road of selection and described measured capacitance circuit are corresponding
The feedback branch that device is different, measures and obtains VcxAnd Vcr1Or Vcr2Or Vcr3, and then by described equation formula 5, formula 6, formula 7,
An equation in formula 9, formula 10, formula 11, formula 13, formula 14, formula 15 is calculated described measured capacitance CxCapacitance, thus
Realize micro-capacitance reference measuring circuit and there is multiple measurement range.
Two, capacitive feedback there is multiple range micro-capacitance reference measuring circuit.
As in figure 2 it is shown, the technical scheme that this embodiment is given has three reference condenser network branch roads and a tested electricity
Capacitive circuit, wherein VinFor driving voltage signal, Cr1、Cr2、Cr3Different for reference electric capacity and capacitance, CxFor measured capacitance, described
Reference electric capacity Cr1、Cr2、Cr3With described measured capacitance CxOne end be connected, described driving voltage signal VinBy this public termination
Enter measuring circuit.
Described reference electric capacity Cr1、Cr2、Cr3The most corresponding operational amplifier N1, N2, N3, and Cr1、Cr2、Cr3The other end
It is respectively connected to the reverse input end of described operational amplifier N1, N2, N3.The in-phase input end of described operational amplifier N1, N2, N3
Ground connection；It is connected in parallel to feedback capacity C between reverse input end and the outfan of described operational amplifier N1f1And feedback resistance
Rf1, between reverse input end and the outfan of described operational amplifier N2, it is connected in parallel to feedback capacity Cf2With feedback resistance Rf2,
It is connected in parallel to feedback capacity C between reverse input end and the outfan of described operational amplifier N3f3With feedback resistance Rf3；Fortune
Calculate the output voltage signal V of the most corresponding three the reference condenser network branch roads of output of amplifier N1, N2, N3cr1、Vcr2、Vcr3。
Described measured capacitance CxCorresponding operational amplifier N4 and CxThe other end access described operational amplifier N4 reverse
Input.The in-phase input end ground connection of described operational amplifier N4；Between reverse input end and the outfan of operational amplifier N4
It is connected in parallel to three feedback branches and feedback resistance Rf4, wherein the first feedback branch 201 has feedback capacity Cf4With switch
Being connected in series of S1B, the second feedback branch 202 has feedback capacity Cf5With switch being connected in series of S2B, the 3rd feedback branch 203
There is feedback capacity Cf6With being connected in series of switch S3B.
Described feedback resistance Rf1、Rf2、Rf3Resistance value bigger, be respectively used to eliminate DC current to described feedback electricity
Hold Cf1、Cf2、Cf3Integrating effect；The most described feedback resistance Rf4Resistance value bigger, be used for eliminating DC current to described
Feedback capacity Cf4、Cf5、Cf6Integrating effect.
For described feedback capacity Cf4, its one end being connected with described switch S1B is connected with one end of switch S1A；Right
In described feedback capacity Cf5, its one end being connected with described switch S2B is connected with one end of switch S2A；For described feedback
Electric capacity Cf6, its one end being connected with described switch S3B is connected with one end of switch S3A；And then by described switch S1A, S2A and
The other end of S3A is connected, and draws the output voltage signal V of described measured capacitance circuit from this common portcx。
The work process of the embodiment shown in Fig. 2 is as follows:
The feedback branch arranging operational amplifier N4 corresponding to described measured capacitance circuit is described first feedback branch
201, the most described switch S1B connect, described switch S2B and S3B disconnects, the most described driving voltage signal VinPut on described
Reference electric capacity Cr1、Cr2、Cr3And described measured capacitance CxAfter, described reference electric capacity Cr1、Cr2、Cr3And described measured capacitance Cx
Electric current respectively with flow through described feedback resistance Cf1、Cf2、Cf3And Cf4Electric current identical, and this electric current flow back into institute respectively
State the outfan of operational amplifier N1, N2, N3 and N4, and then the output voltage V of described operational amplifier N1, N2, N3cr1、
Vcr2、Vcr3Respectively equal to described feedback capacity Cf1、Cf2、Cf3Voltage；Described switch S1A connects, described switch S2A and S3A
Disconnect, and then obtain described feedback capacity Cf4Voltage, this voltage is equal to the output voltage V of described measured capacitance circuitcx.By
This can obtain:
Formula 16
Formula 17
Formula 18
Formula 19
Formula 20
Formula 21
Formula 22
The feedback branch arranging operational amplifier N4 corresponding to described measured capacitance branch road is described second feedback branch
202, the most described switch S2B connect, described switch S1B and S3B disconnects, the most described driving voltage signal VinPut on described
Reference electric capacity Cr1、Cr2、Cr3And described measured capacitance CxAfter, described reference electric capacity Cr1、Cr2、Cr3And described measured capacitance Cx
Electric current respectively with flow through described feedback capacity Cf1、Cf2、Cf3And Cf5Electric current identical, and these electric currents flow back into respectively
The outfan of described operational amplifier N1, N2, N3 and N4, and then the output voltage V of described operational amplifier N1, N2, N3cr1、
Vcr2、Vcr3Respectively equal to described feedback capacity Cf1、Cf2、Cf3Voltage；Described switch S2A connects, described switch S1A and S3A
Disconnect, and then obtain described feedback capacity Cf5Voltage, this voltage is equal to the output voltage V of described measured capacitance circuitcx.By
This can obtain:
Formula 23
Formula 24
Formula 25
Formula 26
The feedback branch arranging operational amplifier N4 corresponding to described measured capacitance branch road is described 3rd feedback branch
203, the most described switch S3B connect, described switch S1B and S2B disconnects, the most described driving voltage signal VinPut on described
Reference electric capacity Cr1、Cr2、Cr3And described measured capacitance CxAfter, described reference electric capacity Cr1、Cr2、Cr3And described measured capacitance Cx
Electric current respectively with flow through described feedback capacity Cf1、Cf2、Cf3And Cf6Electric current identical, and this electric current flow back into institute respectively
State the outfan of operational amplifier N1, N2, N3 and N4, and then the output voltage V of described operational amplifier N1, N2, N3cr1、
Vcr2、Vcr3Respectively equal to described feedback capacity Cf1、Cf2、Cf3Voltage；Described switch S3A connects, described switch S1A and S2A
Disconnect, and then obtain described feedback capacity Cf6Voltage, this voltage is equal to the output voltage V of described measured capacitance circuitcx.By
This can obtain:
Formula 27
Formula 28
Formula 29
Formula 30
C in described equation formula 20, formula 21, formula 22, formula 24, formula 25, formula 26, formula 28, formula 29, formula 30r1、Cr2And Cr3Point
It is not used for representing described reference electric capacity Cr1、Cr2And Cr3Capacitance, owing to the capacitance of described reference electric capacity is different, therefore this
C in a little equatioiesr1、Cr2And Cr3For different numerical value.
By feedback capacity C in described first feedback branch 201f4, feedback capacity in described second feedback branch 202
Cf5, feedback capacity C in described 3rd feedback branch 203f6Resistance value be set to different numerical value, and then described equation formula
20, the C in formula 21, formula 22, formula 24, formula 25, formula 26, formula 28, formula 29, formula 30f4、Cf5And Cf6For different numerical value.
By the operation amplifier that the different described reference capacitance measurement branch road of selection and described measured capacitance circuit are corresponding
The feedback branch that device is different, measures and obtains VcxAnd Vcr1Or Vcr2Or Vcr3, and then by described equation formula 20, formula 21, formula
22, an equation in formula 24, formula 25, formula 26, formula 28, formula 29, formula 30 is calculated described measured capacitance CxCapacitance,
It is achieved in micro-capacitance reference measuring circuit and there is multiple measurement range.
It should be noted that the above is only preferred implementation of the present utility model, it is noted that for this technology
For the those of ordinary skill in field, the equivalent done on the premise of without departing from the design of this utility model principle and principle becomes
Change, revise and combine, protection domain of the present utility model all should be belonged to.
Claims (8)
1. there is multiple range micro-capacitance reference measuring circuit, it is characterised in that described multiple range micro-electric capacity reference measurement electricity
Road includes multichannel reference capacitance test circuit and a road measured capacitance test circuit, and described reference capacitance test circuit is put by computing
Big device, reference electric capacity and feedback impedance composition, the capacitance of multichannel reference electric capacity is different, and one end of reference electric capacity is connected to
The inverting input of operational amplifier, the in-phase input end of operational amplifier is connected to ground, and feedback impedance is connected across operation amplifier
Between device inverting input and operational amplifier output terminal；Described measured capacitance test circuit includes operational amplifier, tested electricity
Hold and the feedback impedance identical with multichannel reference capacitance test circuit way and multipath control switch, one end of measured capacitance
Being connected to the inverting input of operational amplifier, the in-phase input end of operational amplifier is connected to ground, and feedback impedance is opened with control
Close connection to be connected across between operational amplifier inverting input and operational amplifier output terminal, driving voltage signal simultaneously with
The multichannel reference electric capacity other end and the measured capacitance other end connect, tension measuring circuit selective the most respectively with many LUSHEN
Connect than the output of capacitance test circuit and the outfan of measured capacitance test circuit.
Multiple range micro-capacitance reference measuring circuit the most according to claim 1, it is characterised in that described multi-channel control is opened
Closing and connect the first multiplexer circuit, described tension measuring circuit is by the second multiplexer circuit and reference capacitance test circuit
Outfan connect, described tension measuring circuit is by the outfan of the 3rd multiplexer circuit and measured capacitance test circuit even
Connecing, the first multiplexer circuit, the second multiplexer circuit, the 3rd multiplexer circuit accept the I/ of a microprocessor respectively
O Interface Controller.
Multiple range micro-capacitance reference measuring circuit the most according to claim 1, it is characterised in that described multichannel reference electricity
The multiple feedback impedance held in test circuit is resistance, and the feedback impedance of described measured capacitance test circuit is resistance, many LUSHEN
It is the different reference capacitances between 1pF to 1000pF than electric capacity.
Multiple range micro-capacitance reference measuring circuit the most according to claim 3, it is characterised in that described measured capacitance is surveyed
The switch that controls of examination circuit is made up of the first switch in parallel and second switch, and the first switch is connected to tension measuring circuit with anti-
Between feed resistance, second switch is connected between operational amplifier output and feedback resistance.
Multiple range micro-capacitance reference measuring circuit the most according to claim 1, it is characterised in that described multichannel reference electricity
The multiple feedback impedance held in test circuit is resistance and electric capacity parallel connection capacitance-resistance impedance, the feedback of described measured capacitance test circuit
Impedance is a resistance and the capacitance-resistance impedance of multichannel electric capacity parallel connection, and a resistance is connected across operational amplifier inverting input and fortune
Calculating between amplifier out, described multichannel electric capacity concatenates a described control switch respectively, and to be connected across operational amplifier anti-phase defeated
Enter between end and operational amplifier output terminal.
Multiple range micro-capacitance reference measuring circuit the most according to claim 5, it is characterised in that described measured capacitance is surveyed
The control switch of examination circuit is made up of the first switch and second switch, and the first switch is connected to tension measuring circuit and feedback capacity
Between, second switch is connected between operational amplifier output and feedback capacity.
Multiple range micro-capacitance reference measuring circuit the most according to claim 1, it is characterised in that described measured capacitance is surveyed
The multiple feedback impedance Zhong mono-road feedback impedance of examination circuit and a road in multichannel reference capacitance test circuit corresponding to selection
The resistance value of feedback impedance is identical.
Multiple range micro-capacitance reference measuring circuit the most according to claim 1, it is characterised in that described multichannel reference electricity
The feedback impedance value holding test circuit is identical, and in described measured capacitance test circuit, multiple feedback resistance value is identical.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620615022.3U CN205880061U (en) | 2016-06-21 | 2016-06-21 | Little electric capacity reference measuring circuit with multrirange |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620615022.3U CN205880061U (en) | 2016-06-21 | 2016-06-21 | Little electric capacity reference measuring circuit with multrirange |
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| Publication Number | Publication Date |
|---|---|
| CN205880061U true CN205880061U (en) | 2017-01-11 |
Family
ID=57691461
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201620615022.3U Withdrawn - After Issue CN205880061U (en) | 2016-06-21 | 2016-06-21 | Little electric capacity reference measuring circuit with multrirange |
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| CN (1) | CN205880061U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105974202A (en) * | 2016-06-21 | 2016-09-28 | 北京华峰测控技术有限公司 | Micro-capacitance reference measurement circuit with multiple measuring ranges and measurement method thereof |
-
2016
- 2016-06-21 CN CN201620615022.3U patent/CN205880061U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105974202A (en) * | 2016-06-21 | 2016-09-28 | 北京华峰测控技术有限公司 | Micro-capacitance reference measurement circuit with multiple measuring ranges and measurement method thereof |
| CN105974202B (en) * | 2016-06-21 | 2019-06-28 | 北京华峰测控技术股份有限公司 | With multiple range micro-capacitance reference measuring circuit and method |
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| GR01 | Patent grant | ||
| CP03 | Change of name, title or address | ||
| CP03 | Change of name, title or address |
Address after: 100000 building 23, 59 South Road, Haidian District, Beijing. Patentee after: Beijing Hua Feng measurement and control technology Limited by Share Ltd Address before: 100070 7 floor, No. 2, No. 1, Haiying Road, Fengtai District, Beijing Patentee before: BEIJING HUAFENG TEST & CONTROL TECHNOLOGY CO., LTD. |
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| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20170111 Effective date of abandoning: 20190628 |