CN203178842U - Alternating-current constant flow source character load circuit for sensor - Google Patents
Alternating-current constant flow source character load circuit for sensor Download PDFInfo
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- CN203178842U CN203178842U CN 201320116551 CN201320116551U CN203178842U CN 203178842 U CN203178842 U CN 203178842U CN 201320116551 CN201320116551 CN 201320116551 CN 201320116551 U CN201320116551 U CN 201320116551U CN 203178842 U CN203178842 U CN 203178842U
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- flow source
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Abstract
Disclosed is an alternating-current constant flow source character load circuit for a sensor. The alternating-current constant flow source character load circuit can be used as a load of the sensor to present the constant flow source character when alternating currents go through. The alternating-current constant flow source load circuit is altogether composed of a triode transistor, a resistor R with the two ends connected between a base and a collector of an audion Q and a capacitor C connected between the base and an emitter of the audion. Due to the bootstrapping effect of the capacitor C, for alternating current signals, the base and the emitter of the audion share the same electric potential, the collector and the emitter of the audion present the constant flow source character, the alternating load impedance of the sensor is greatly improved, and the signal transmission efficiency of the sensor is improved.
Description
Technical field
The utility model relates to a kind of electronic circuit, it as the sensor load circuit alternating current by the time present the constant current source characteristic.
Background technology
Sensor is the indispensable electronic component of modern automatic control system, and many sensors externally present the constant current source characteristic in electronic circuit, need cooperate with the high-resistance load circuit usually in order to obtain bigger signal voltage.The photodiode sensor D among Fig. 1 for example, it presents the constant current source characteristic under the illumination effect, and the strength of current difference that the difference of intensity of illumination is passed through, resistance R are its pull-up resistors.In order to obtain enough signal voltages, the resistance of R must obtain very big.Enough bias currents are arranged because the resistance of R allows greatly again on the D, the voltage that just needs to improve power supply E guarantees the circuit operate as normal.The big resistance of the high voltage of E and R, the both brings adverse influence to the miniaturization of electronic equipment.
Summary of the invention
Technical problem to be solved in the utility model is: at the sensor application circuit of constant current source characteristic, adopt the electronic load circuit to serve as, when improving the load AC impedance, reduce the Equivalent DC impedance and provide enough bias currents for sensor, thereby realization low voltage power supply, simplify and reduced requirement to electronic equipment power source, be conducive to realize the miniaturization of electronic equipment.
The technical scheme that its technical matters that will solve the utility model adopts is: be made up of resistance R, capacitor C, triode Q, its essential characteristic is that the resistance R two ends are connected between the base stage and collector of triode Q, capacitor C is connected between the base stage and emitter of triode, collector connects a port of power supply, and emitter is received a load port of sensor.Resistance R, capacitor C, triode Q form sensor AC constant-current source load circuit jointly.
Use the utility model obtainable two big usefulness: the one, provide dc bias current by transistor emitter to sensor, when changing, the dc bias current of sensor influences the voltage at sensor two ends height, this voltage height can cause the transistor emitter potential change, thereby leads triode U processed
BeChange feasible I by triode
eFollow variation, realize regulating automatically the dc bias current of sensor, greatly reduce supply voltage when guaranteeing to satisfy sensor direct current biasing needs, the supply voltage that very is conducive to reduce electronic equipment is simplified the miniaturization that power supply architecture is realized equipment.The 2nd, because the boot strap of capacitor C, the base stage of triode and emitter are idiostatic for the ac signal that passes through, present the AC constant-current source characteristic between transistor collector and the emitter, improve sensor greatly and exchanged equivalent load impedance, thereby improved the output voltage signal intensity that sensor obtains.
Description of drawings
Accompanying drawing 1 is common photodiode sensor circuit synoptic diagram, and R is the pull-up resistor of photosensitive tube among the figure, and E is bias supply.
Accompanying drawing 2 is this sensor AC constant-current source load circuit schematic diagram, and Q is that load triode, R are that the base biasing resistor, C of triode is that electric capacity, E are power supply for exchanging bootstrapping, and P1, P2 connect sensor.
Accompanying drawing 3 is the application special case of the utility model in the photoelectric sensor photoelectric conversion circuit, D is the photodiode photoelectric sensor, the effect of Q, R, C, E is identical with accompanying drawing 2, forms load circuit jointly as the load of sensor D, and P is sensor electrical translation circuit signal output part.
Accompanying drawing 4 is the special case of the utility model in sound transducer is used, and MIC is that sound transducer is commonly called as microphone, is used for receiving voice signal, and the effect of Q, R, C, E is identical with accompanying drawing 3, and P is the audio signal output terminal after the conversion.If change microphone into ultrasonic sensor, this special case can also be applied in the ultrasonic sensor translation circuit.
Embodiment
Consult shown in accompanying drawing 2 circuit, the base biasing resistor that resistance R is connected between the base stage and collector of triode, the current collection rubbish is connected to power end, R constitutes triode Q constitutes the loop in the telegram in reply source for Q provides a load end that direct current biasing, transistor emitter receive sensor side again by another common port of sensor.The bias voltage difference of sensor self directly has influence on the emitter voltage of Q, and this voltage passes through U
BeChange the emitter current I that causes Q
eChange, realize that the self-adaptation of DC loop electric current is regulated.Though this signal also can cause the emitter potential change when sensor receives AC signal, AC signal can cause the variation of base potential to the base stage of Q by capacitive feedback, and both co-variations have been offset the variation of emitter junction current potential, makes Δ u
Bc=0 triode QI
eInvariable triode presents the constant current source characteristic.
Accompanying drawing 3 is the utility model application special cases in photoelectric sensor.Sensor among the figure is photodiode D, and PN junction was by a constant leakage current when photodiode oppositely connected, and this electric current changes realization to the receiving conversion of light signal with intensity of illumination is different.DC current size by photosensitive tube when illumination is constant is determined that by the transistor emitter current potential undercurrent current potential descends and causes U
BeIncrease and drive I
eIncrease, on the contrary suitable right, well adapted to the biasing requirement of photosensitive tube automatically.When AC signal shines on the photosensitive tube D, D two terminal potentials change, and this variation feeds back to transistor base by capacitor C, has changed base potential and has led Δ u processed
BcThe collector-emitter current of=0 triode presents constant current source, has strengthened the converting electrical signal rate of photosensitive tube greatly, has improved the output signal strength of photodiode sensor circuit, and this figure signal is finally exported to subsequent conditioning circuit by common port and P end and used.
Accompanying drawing 4 is circuit that the utility model is applied to ultrasonic sensor.MIC is ultrasonic sensor, and ultrasonic sensor mostly is made of electret usually, and inside has embedded field effect transistor as impedance variation.The discreteness of field effect transistor bias current is very big, the emitter potential change that bias current varies in size and has influence on triode when being applied in this circuit, and the former reason triode identical with accompanying drawing 3 comes self-adaptation.What induce on the sensor when ultrasonic signal arrives is AC signal, and triode presents the constant current source characteristic again, and this characteristic constitutes the load of sensor, has realized efficient conversion and the transmission of ultrasonic sensor.
Claims (1)
1. a sensor is with AC constant-current source characteristic load circuit, formed by resistance R, capacitor C, triode Q, its essential characteristic is: the resistance R two ends are connected between the base stage and collector of triode Q, capacitor C is connected between the base stage and emitter of triode, collector connects a port of power supply, and emitter is received a load port of sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320116551 CN203178842U (en) | 2013-03-05 | 2013-03-05 | Alternating-current constant flow source character load circuit for sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320116551 CN203178842U (en) | 2013-03-05 | 2013-03-05 | Alternating-current constant flow source character load circuit for sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203178842U true CN203178842U (en) | 2013-09-04 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201320116551 Expired - Fee Related CN203178842U (en) | 2013-03-05 | 2013-03-05 | Alternating-current constant flow source character load circuit for sensor |
Country Status (1)
| Country | Link |
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| CN (1) | CN203178842U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109802654A (en) * | 2019-02-15 | 2019-05-24 | 广东寰宇电子科技股份有限公司 | A kind of high AC impedance circuit and its application system |
-
2013
- 2013-03-05 CN CN 201320116551 patent/CN203178842U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109802654A (en) * | 2019-02-15 | 2019-05-24 | 广东寰宇电子科技股份有限公司 | A kind of high AC impedance circuit and its application system |
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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: 20130904 Termination date: 20140305 |