CN103176052A - Capacitance type sensor connector circuit - Google Patents
Capacitance type sensor connector circuit Download PDFInfo
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- CN103176052A CN103176052A CN 201110430249 CN201110430249A CN103176052A CN 103176052 A CN103176052 A CN 103176052A CN 201110430249 CN201110430249 CN 201110430249 CN 201110430249 A CN201110430249 A CN 201110430249A CN 103176052 A CN103176052 A CN 103176052A
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Abstract
The invention discloses a capacitance type sensor connector circuit which comprises a charge transmission circuit, a detection circuit and a differential amplification circuit. The charge transmission circuit is symmetrical to the detection circuit, and the differential amplification circuit is connected behind the charge transmission circuit and the detection circuit. By means of the mode, influence caused by stray capacitance can be avoided when the charge transmission circuit detects tiny capacitance, and the capacitance type sensor connector circuit greatly improves stability and detection sensitivity.
Description
Technical field
The present invention relates to the sensor interface circuitry field, particularly relate to a kind of capacitance type sensor interface circuit.
Background technology
The capacitance silicon micro sensor system is widely used in the fields such as locomotive, medical treatment and Industry Control, the interface of Detection capacitance and signal processing circuit is one of subject matter of this type of Microsystems Design, under a lot of situations, interface has determined the resolution of micro sensor system to detection limit, in micro-system, often have larger stray capacitance and Detection capacitance to exist simultaneously, large stray capacitance can reduce interface circuit to a great extent to the resolution of little change Detection capacitance.
Traditional interface circuit structure that is used for this type of small capacitance detection is complicated, and its resolution is subject to effect of parasitic capacitance.Some switched-capacitor circuits simple in structure provide fully integrated solution, but because itself and the charge injection of capacitance type sensor interface MOS switch and the error of introducing are restricted the performance of circuit.The charge transfer circuit that changes for detection of small capacitance is not subjected to the impact of stray capacitance, and the subtle change of the accurate voltage of present electric charge and little change Detection capacitance initial value and the raising that large drift has also limited its resolution occurs.
Summary of the invention
The technical matters that the present invention mainly solves is to provide a kind of capacitance type sensor interface circuit, can keep charge transfer circuit to detect small capacitance and change the impact that is not subjected to stray capacitance, has greatly improved stability and the detection sensitivity of circuit.
For solving the problems of the technologies described above, the technical scheme that the present invention adopts is: a kind of capacitance type sensor interface circuit is provided, comprise: charge transfer circuit, testing circuit and differential amplifier circuit, described charge transfer circuit and testing circuit are symmetrical structure, after described differential amplifier circuit is connected to charge transfer circuit and testing circuit.
in a preferred embodiment of the present invention, described charge transfer circuit comprises: the first switch, second switch, the 3rd switch, the 4th switch, the 5th switch, the 6th switch, the first electric capacity, the second electric capacity, the 3rd electric capacity, the 4th electric capacity, the first amplifier and the second amplifier, described second switch, the 3rd switch and the 5th switch in parallel one end ground connection, the other end and first electric capacity of connecting, the second electric capacity, the 3rd electric capacity is connected with the 4th electric capacity one end, described the first electric capacity and the 4th electric capacity other end ground connection, described the first switch also connects the first electric capacity one end, described the 6th switch also connects the 4th electric capacity one end, described the 4th switch one is terminated between the second electric capacity and the 3rd electric capacity, another termination first amplifier, after described the second amplifier is connected with the first amplifier and is connected to the first amplifier.
in a preferred embodiment of the present invention, described testing circuit comprises: minion is closed, the 8th switch, the 9th switch, the tenth switch, the 11 switch, twelvemo is closed, the 5th electric capacity, the 6th electric capacity, the 7th electric capacity, the 8th electric capacity, the 3rd amplifier and the 4th amplifier, described the 8th switch, the 9th switch and the 11 switch in parallel one end ground connection, the other end and the 5th electric capacity of connecting, the 6th electric capacity, the 7th electric capacity, the 8th electric capacity one end is connected, described the 5th electric capacity and the 8th electric capacity other end ground connection, the 5th electric capacity one end is closed and connect to described minion, the 8th electric capacity one end is closed and connect to described twelvemo, described the tenth switch one is terminated between the 6th electric capacity and the 7th electric capacity, another termination the 3rd amplifier, after described the 4th amplifier is connected with the 3rd amplifier and is connected to the 3rd amplifier.
In a preferred embodiment of the present invention, described the second electric capacity and the 3rd electric capacity are differential capacitance, and described the first electric capacity and the 4th electric capacity are stray capacitance.
In a preferred embodiment of the present invention, described the 6th electric capacity and the 7th electric capacity are with reference to differential capacitance, and described the 5th electric capacity and the 8th electric capacity are with reference to stray capacitance.
In a preferred embodiment of the present invention, described the first switch, second switch, the 3rd switch, the 4th switch, the 5th switch, the 6th switch are cmos switch.
In a preferred embodiment of the present invention, described minion pass, the 8th switch, the 9th switch, the tenth switch, the 11 switch, twelvemo are closed and are cmos switch.
In a preferred embodiment of the present invention, described first amplifier anti-phase input termination the first resistance, the 9th electric capacity and the tenth electric capacity one end, the in-phase input end of described the first resistance and the 9th electric capacity other end and the second amplifier connects the first amplifier and gets output terminal, another termination first amplifier in-phase input end and ground connection of described the tenth electric capacity, the anti-phase input termination differential amplifier circuit of described the second operational amplifier.
In a preferred embodiment of the present invention, described the 3rd amplifier anti-phase input termination the second resistance, the 11 electric capacity and the 12 electric capacity one end, the in-phase input end of described the second resistance and the 11 electric capacity other end and the 4th amplifier connects the 3rd amplifier and gets output terminal, another termination the 3rd amplifier in-phase input end and ground connection of described the 12 electric capacity, the anti-phase input termination differential amplifier circuit of described four-operational amplifier.
In a preferred embodiment of the present invention, described differential amplifier circuit comprises: the 5th amplifier, the 3rd resistance, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance and the 13 electric capacity, described the 5th amplifier in-phase input end connects the 4th resistance and the 6th resistance and ground connection in parallel, the 3rd resistance and the 5th resistance of described the 5th amplifier anti-phase input termination parallel connection, described the 5th resistance other end is connected with the 7th resistance one end with the 5th amplifier out, described the 7th resistance and the 13 capacitances in series ground connection.
The invention has the beneficial effects as follows: introduce with reference to differential capacitance and corresponding testing circuit in the Micro-Variation Capacitance Sensor system of capacitance type sensor interface circuit of the present invention take charge transfer circuit as interface, by differential amplification is carried out in the output of this circuit part and the output of testing circuit part, can obtain the working point does not change with reference voltage and Detection capacitance initial value, and has an output signal of high-resolution, in addition, this circuit can make charge transfer circuit detect the impact that the small capacitance variation is not subjected to stray capacitance.
Description of drawings
Fig. 1 is charge transfer circuit principle schematic of the present invention;
In accompanying drawing, the mark of each parts is as follows: 1, charge transfer circuit 2, testing circuit 3, differential amplifier circuit.
Embodiment
Below in conjunction with accompanying drawing, preferred embodiment of the present invention is described in detail, thereby so that advantages and features of the invention can be easier to be it will be appreciated by those skilled in the art that, protection scope of the present invention is made more explicit defining.
See also Fig. 1, the embodiment of the present invention comprises: charge transfer circuit 1, testing circuit 2 and differential amplifier circuit 3, charge transfer circuit 1 and testing circuit 2 are symmetrical structure, after differential amplifier circuit 3 is connected to charge transfer circuit 1 and testing circuit 2.
Differential amplifier circuit 3 comprises: amplifier U5, resistance R 1, resistance R 2, resistance R 3, resistance R 4, resistance R _ f and capacitor C f, amplifier U5 in-phase input end connects resistance R 2 in parallel and resistance R 4 and ground connection, resistance R 1 and the resistance R 3 of the parallel connection of amplifier U5 anti-phase input termination, resistance R 3 other ends are connected with resistance R _ f one end with amplifier U5 output terminal, the described resistance R _ f ground connection of connecting with capacitor C f.
Be different from prior art, introduce with reference to differential capacitance and corresponding testing circuit in the Micro-Variation Capacitance Sensor system of capacitance type sensor interface circuit of the present invention take charge transfer circuit as interface, by differential amplification is carried out in the output of this circuit part and the output of testing circuit part, can obtain the working point does not change with reference voltage and Detection capacitance initial value, and has an output signal of high-resolution, in addition, this circuit can make charge transfer circuit detect the impact that the small capacitance variation is not subjected to stray capacitance.
The principle of work of capacitance type sensor interface circuit of the present invention: switch S 1 is controlled by non-overlapping two-phase (CK1, CK2) high frequency clock to switch S 6, clock CK1 control period, switch S 1, S3, S5 closure, other switch opens, capacitor C S1, CS2, CP1 and CP2 are recharged; Clock CK2 control period, switch S 2, S4, S closure, other switch opens, capacitor C S1, CS2, CP1 and CP2 are recharged.Because capacitor C S1, lotus that CS2 charges difference have electric current to flow through S4, do not flow through S4 when capacitor C P1, lotus that CP2 charges discharge, thereby circuit is not subjected to the impact of stray capacitance CP1 and CP2, the testing circuit principle of work is identical with charge transfer circuit, and differential amplification is carried out in the output of charge transfer circuit and the output of testing circuit.
The above is only embodiments of the invention; not thereby limit the scope of the claims of the present invention; every equivalent structure or equivalent flow process conversion that utilizes instructions of the present invention and accompanying drawing content to do; or directly or indirectly be used in other relevant technical fields, all in like manner be included in scope of patent protection of the present invention.
Claims (10)
1. capacitance type sensor interface circuit, it is characterized in that, comprise: charge transfer circuit, testing circuit and differential amplifier circuit, described charge transfer circuit and testing circuit are symmetrical structure, after described differential amplifier circuit is connected to charge transfer circuit and testing circuit.
2. capacitance type sensor interface circuit according to claim 1, it is characterized in that, described charge transfer circuit comprises: the first switch, second switch, the 3rd switch, the 4th switch, the 5th switch, the 6th switch, the first electric capacity, the second electric capacity, the 3rd electric capacity, the 4th electric capacity, the first amplifier and the second amplifier, described second switch, the 3rd switch and the 5th switch in parallel one end ground connection, the other end and first electric capacity of connecting, the second electric capacity, the 3rd electric capacity is connected with the 4th electric capacity one end, described the first electric capacity and the 4th electric capacity other end ground connection, described the first switch also connects the first electric capacity one end, described the 6th switch also connects the 4th electric capacity one end, described the 4th switch one is terminated between the second electric capacity and the 3rd electric capacity, another termination first amplifier, after described the second amplifier is connected with the first amplifier and is connected to the first amplifier.
3. capacitance type sensor interface circuit according to claim 1, it is characterized in that, described testing circuit comprises: minion is closed, the 8th switch, the 9th switch, the tenth switch, the 11 switch, twelvemo is closed, the 5th electric capacity, the 6th electric capacity, the 7th electric capacity, the 8th electric capacity, the 3rd amplifier and the 4th amplifier, described the 8th switch, the 9th switch and the 11 switch in parallel one end ground connection, the other end and the 5th electric capacity of connecting, the 6th electric capacity, the 7th electric capacity, the 8th electric capacity one end is connected, described the 5th electric capacity and the 8th electric capacity other end ground connection, the 5th electric capacity one end is closed and connect to described minion, the 8th electric capacity one end is closed and connect to described twelvemo, described the tenth switch one is terminated between the 6th electric capacity and the 7th electric capacity, another termination the 3rd amplifier, after described the 4th amplifier is connected with the 3rd amplifier and is connected to the 3rd amplifier.
4. capacitance type sensor interface circuit according to claim 2, is characterized in that, described the second electric capacity and the 3rd electric capacity are differential capacitance, and described the first electric capacity and the 4th electric capacity are stray capacitance.
5. capacitance type sensor interface circuit according to claim 3, is characterized in that, described the 6th electric capacity and the 7th electric capacity are with reference to differential capacitance, and described the 5th electric capacity and the 8th electric capacity are with reference to stray capacitance.
6. capacitance type sensor interface circuit according to claim 2, is characterized in that, described the first switch, second switch, the 3rd switch, the 4th switch, the 5th switch, the 6th switch are cmos switch.
7. capacitance type sensor interface circuit according to claim 3, is characterized in that, described minion pass, the 8th switch, the 9th switch, the tenth switch, the 11 switch, twelvemo are closed and be cmos switch.
8. capacitance type sensor interface circuit according to claim 3, it is characterized in that, described first amplifier anti-phase input termination the first resistance, the 9th electric capacity and the tenth electric capacity one end, the in-phase input end of described the first resistance and the 9th electric capacity other end and the second amplifier connects the first amplifier and gets output terminal, another termination first amplifier in-phase input end and ground connection of described the tenth electric capacity, the anti-phase input termination differential amplifier circuit of described the second operational amplifier.
9. capacitance type sensor interface circuit according to claim 4, it is characterized in that, described the 3rd amplifier anti-phase input termination the second resistance, the 11 electric capacity and the 12 electric capacity one end, the in-phase input end of described the second resistance and the 11 electric capacity other end and the 4th amplifier connects the 3rd amplifier and gets output terminal, another termination the 3rd amplifier in-phase input end and ground connection of described the 12 electric capacity, the anti-phase input termination differential amplifier circuit of described four-operational amplifier.
10. capacitance type sensor interface circuit according to claim 1, it is characterized in that, described differential amplifier circuit comprises: the 5th amplifier, the 3rd resistance, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance and the 13 electric capacity, described the 5th amplifier in-phase input end connects the 4th resistance and the 6th resistance and ground connection in parallel, the 3rd resistance and the 5th resistance of described the 5th amplifier anti-phase input termination parallel connection, described the 5th resistance other end is connected with the 7th resistance one end with the 5th amplifier out, described the 7th resistance and the 13 capacitances in series ground connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110430249 CN103176052A (en) | 2011-12-21 | 2011-12-21 | Capacitance type sensor connector circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110430249 CN103176052A (en) | 2011-12-21 | 2011-12-21 | Capacitance type sensor connector circuit |
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|---|---|
| CN103176052A true CN103176052A (en) | 2013-06-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201110430249 Pending CN103176052A (en) | 2011-12-21 | 2011-12-21 | Capacitance type sensor connector circuit |
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| CN (1) | CN103176052A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108985150A (en) * | 2017-05-31 | 2018-12-11 | 联咏科技股份有限公司 | Condenser type imaging sensor |
| CN109557143A (en) * | 2018-10-30 | 2019-04-02 | 电子科技大学 | A kind of capacitive humidity sensor interface circuit |
| CN109714082A (en) * | 2018-12-25 | 2019-05-03 | 中南大学 | A kind of dual mode transducer based on RF energy perception |
-
2011
- 2011-12-21 CN CN 201110430249 patent/CN103176052A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108985150A (en) * | 2017-05-31 | 2018-12-11 | 联咏科技股份有限公司 | Condenser type imaging sensor |
| CN108985150B (en) * | 2017-05-31 | 2022-05-27 | 联咏科技股份有限公司 | Capacitive image sensor |
| CN109557143A (en) * | 2018-10-30 | 2019-04-02 | 电子科技大学 | A kind of capacitive humidity sensor interface circuit |
| CN109714082A (en) * | 2018-12-25 | 2019-05-03 | 中南大学 | A kind of dual mode transducer based on RF energy perception |
| CN109714082B (en) * | 2018-12-25 | 2021-04-20 | 中南大学 | Dual-mode sensor based on radio frequency energy perception |
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Application publication date: 20130626 |