CN203561373U - Measuring circuit of capacitive transducer - Google Patents
Measuring circuit of capacitive transducer Download PDFInfo
- Publication number
- CN203561373U CN203561373U CN201320736619.XU CN201320736619U CN203561373U CN 203561373 U CN203561373 U CN 203561373U CN 201320736619 U CN201320736619 U CN 201320736619U CN 203561373 U CN203561373 U CN 203561373U
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- operational amplifier
- input end
- resistance
- capacitive transducer
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Abstract
The utility model discloses the measuring circuit of a capacitive transducer, which comprises a first operational amplifier and a second operational amplifier. A resistor R1 is connected between the non-inverted input end and the output end of the first operational amplifier. A resistor R2 is connected between the inverted output end and the input end of the first operational amplifier. The inverted output end of the first operational amplifier is grounded through a resistor R7. The non-inverted input end of the first operational amplifier is connected with a capacitor C1 and is also connected with the inverted input end of the second operational amplifier. The non-inverted input end of the second operational amplifier is grounded through a resistor R3. A resistor R4 is connected between the inverted input end and the output end of the second operational amplifier. The output end of the second operational amplifier is connected with a zero-crossing comparison circuit. The measuring circuit of the capacitive transducer is high in data measuring accuracy and meets the high measurement requirements in multiple fields.
Description
Technical field
The utility model relates to a kind of metering circuit, relates in particular a kind of metering circuit of capacitive transducer.
Background technology
Capacitive transducer have that measurement range is large, highly sensitive, the advantage such as dynamic response is fast, good stability, especially very little in measurement mechanical moment and do not need to carry out any type of pre-conversion, therefore it has application in a lot of fields, especially in the non-contact measurement field of the physical quantitys such as displacement, pressure or acceleration.The metering circuit of capacitive transducer is mainly the change of electric capacity to be converted to the variation of voltage or electric current.In a lot of fields, in the measuring process of degree speed, acceleration, to the measuring accuracy of data require high.
Utility model content
The utility model provides a kind of metering circuit of capacitive transducer, and the measuring accuracy of its data is high, meets the measurement needs of multi-field high request.
For solving above-mentioned technical matters, the utility model by the following technical solutions:
The metering circuit of capacitive transducer, it comprises the first operational amplifier and the second operational amplifier, between the in-phase input end of the first described operational amplifier and output terminal, be connected with resistance R 1, between the reversed-phase output of the first operational amplifier and output terminal, be connected with resistance R 2, the reversed-phase output of the first operational amplifier is connected to the ground by resistance R 7, on the in-phase input end of the first described operational amplifier, be connected with capacitor C 1, the in-phase input end of the first described operational amplifier is connected on the inverting input of the second operational amplifier, the in-phase input end of the second described operational amplifier is connected to the ground by resistance R 3, between the inverting input of the second operational amplifier and output terminal, be connected with resistance R 4, on the output terminal of the second operational amplifier, be connected with zero passage comparator circuit.
Further technical scheme is:
As preferably, comparator circuit comprises the 3rd operational amplifier, the in-phase input end ground connection of the 3rd described operational amplifier, the reverse input end of the 3rd operational amplifier is connected to by resistance R 5 on the output terminal of the second operational amplifier, and the inverting input of the 3rd operational amplifier is connected to the ground by resistance R 6.
Further, the model of operational amplifier is AD818.
Further, the model of the 3rd described operational amplifier is LT1719.
Compared with prior art, the beneficial effects of the utility model are:
The utility model utilization be take the multivibrator that the first operational amplifier is core the volume change of electric capacity is carried out to converted measurement, and the second operational amplifier carries out negative sense feedback to electric capacity, and utilize zero passage comparator circuit to process capacitance variations value, can effectively improve the measuring accuracy to capacitance variations, make it be applicable to multi-field high-precision measurement demand.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the utility model is described in further detail.
Fig. 1 is circuit theory diagrams of the present utility model.
Embodiment
Below in conjunction with accompanying drawing, the utility model is further described.Embodiment of the present utility model includes but not limited to the following example.
[embodiment]
The metering circuit of capacitive transducer as shown in Figure 1, it comprises the first operational amplifier and the second operational amplifier, between the in-phase input end of the first described operational amplifier and output terminal, be connected with resistance R 1, between the reversed-phase output of the first operational amplifier and output terminal, be connected with resistance R 2, the reversed-phase output of the first operational amplifier is connected to the ground by resistance R 7, on the in-phase input end of the first described operational amplifier, be connected with capacitor C 1, the in-phase input end of the first described operational amplifier is connected on the inverting input of the second operational amplifier, the in-phase input end of the second described operational amplifier is connected to the ground by resistance R 3, between the inverting input of the second operational amplifier and output terminal, be connected with resistance R 4, on the output terminal of the second operational amplifier, be connected with zero passage comparator circuit.In the utility model, utilize the first operational amplifier to form multivibrator, the variation of capacitance is converted into the variation of output frequency, it can make to export before and after the pulse of square wave more precipitous.Operational amplifier and peripheral circuit carry out negative sense compensation to the capacity of electric capacity, when compensation power down, hold after the capacity of body, and output frequency will have the rising of certain amplitude.Zero passage comparator circuit can make the output pulse of the first operational amplifier and the level of follow-up frequency senser compatibility, and the conversion between its applicable bidirectional analog signal and single supply logic level, also makes circuit more succinct.Utilize two operational amplifiers and zero passage comparator circuit to measure capacitor's capacity, the accuracy of detection that it is changed capacitor's capacity is high, makes it be applicable to multi-field high-precision measurement demand.
Described zero passage comparator circuit comprises the 3rd operational amplifier, the in-phase input end ground connection of the 3rd described operational amplifier, the reverse input end of the 3rd operational amplifier is connected to by resistance R 5 on the output terminal of the second operational amplifier, and the inverting input of the 3rd operational amplifier is connected to the ground by resistance R 6.Zero passage comparator circuit mainly consists of a pre-computation amplifier, and it is simple in structure, can simplify circuit and connect.
In order to reduce measuring error, improve accuracy of detection, the model of the first described operational amplifier is AD818.AD818 is high precision, low noise operational amplifier, and the representative value of its common mode input capacitance is only 1.5Pf, can reduce the measuring error of operational amplifier when with sensor body Capacitance parallel connection.
In order to improve further raising accuracy of detection, the model of the 3rd described operational amplifier is LT1719.LT1719 is low pressure, dual power supply comparer at a high speed, the dual power supply of chip input end and the single supply of output terminal arrange separately at chip internal, therefore be well suited for the conversion of casing between simulating signal and single supply logic level, make circuit structure simple, can reduce measuring error.
Be as mentioned above embodiment of the present utility model.The utility model is not limited to above-mentioned embodiment, and anyone should learn the structural change of making under enlightenment of the present utility model, every with the utlity model has identical or close technical scheme, within all falling into protection domain of the present utility model.
Claims (4)
1. the metering circuit of capacitive transducer, it is characterized in that: it comprises the first operational amplifier and the second operational amplifier, between the in-phase input end of the first described operational amplifier and output terminal, be connected with resistance R 1, between the reversed-phase output of the first operational amplifier and output terminal, be connected with resistance R 2, the reversed-phase output of the first operational amplifier is connected to the ground by resistance R 7, on the in-phase input end of the first described operational amplifier, be connected with capacitor C 1, the in-phase input end of the first described operational amplifier is connected on the inverting input of the second operational amplifier, the in-phase input end of the second described operational amplifier is connected to the ground by resistance R 3, between the inverting input of the second operational amplifier and output terminal, be connected with resistance R 4, on the output terminal of the second operational amplifier, be connected with zero passage comparator circuit.
2. the metering circuit of capacitive transducer according to claim 1, it is characterized in that: described zero passage comparator circuit comprises the 3rd operational amplifier, the in-phase input end ground connection of the 3rd described operational amplifier, the reverse input end of the 3rd operational amplifier is connected to by resistance R 5 on the output terminal of the second operational amplifier, and the inverting input of the 3rd operational amplifier is connected to the ground by resistance R 6.
3. the metering circuit of capacitive transducer according to claim 1 and 2, is characterized in that: the model of the first described operational amplifier is AD818.
4. the metering circuit of capacitive transducer according to claim 2, is characterized in that: the model of the 3rd described operational amplifier is LT1719.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320736619.XU CN203561373U (en) | 2013-11-21 | 2013-11-21 | Measuring circuit of capacitive transducer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320736619.XU CN203561373U (en) | 2013-11-21 | 2013-11-21 | Measuring circuit of capacitive transducer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203561373U true CN203561373U (en) | 2014-04-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320736619.XU Expired - Fee Related CN203561373U (en) | 2013-11-21 | 2013-11-21 | Measuring circuit of capacitive transducer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203561373U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103743420A (en) * | 2013-11-21 | 2014-04-23 | 成都市宏山科技有限公司 | Measuring circuit for capacitance sensor |
| CN104316087A (en) * | 2014-09-30 | 2015-01-28 | 广东合微集成电路技术有限公司 | Measuring circuit of capacitive sensor |
-
2013
- 2013-11-21 CN CN201320736619.XU patent/CN203561373U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103743420A (en) * | 2013-11-21 | 2014-04-23 | 成都市宏山科技有限公司 | Measuring circuit for capacitance sensor |
| CN104316087A (en) * | 2014-09-30 | 2015-01-28 | 广东合微集成电路技术有限公司 | Measuring circuit of capacitive sensor |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140423 Termination date: 20141121 |
|
| EXPY | Termination of patent right or utility model |