CN219417649U - Weak current detection circuit for photodiode - Google Patents
Weak current detection circuit for photodiode Download PDFInfo
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- CN219417649U CN219417649U CN202320216909.5U CN202320216909U CN219417649U CN 219417649 U CN219417649 U CN 219417649U CN 202320216909 U CN202320216909 U CN 202320216909U CN 219417649 U CN219417649 U CN 219417649U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The utility model discloses a weak current detection circuit for a photodiode, which comprises a front-stage amplification circuit and a rear-stage amplification circuit, wherein the front-stage amplification circuit is provided with a first operational amplifier, a first pin of the first operational amplifier is electrically connected with the rear-stage amplification circuit through a resistor, the first pin is reversely connected with a fourth pin of the first operational amplifier through a feedback resistor, a third pin of the first operational amplifier is grounded, and the fourth pin is electrically connected with the output end of the photodiode; the post-stage amplifying circuit is provided with a second operational amplifier, the second operational amplifier comprises a first channel and a second channel, a first pin of the first channel is electrically connected with a fifth pin of the second channel through a filter circuit, the first pin of the first channel is reversely connected with a second pin of the first channel through a feedback resistor, a third pin of the first channel is electrically connected with a parallel circuit formed by the fifth resistor and a sixth resistor and grounded, and a sixth pin of the second channel is electrically connected with a seventh pin.
Description
Technical Field
The utility model relates to the field of photodiode signal detection, in particular to a weak current detection circuit for a photodiode.
Background
Photodiodes are one type of photo-sensing device that converts optical signals into electrical signals, and are used in a variety of applications, such as aerospace, astronomy, weather, military, industrial and civil applications. Photodiodes accept light energy as input to produce current, but the output current signal is typically extremely weak. When the weak current signal is acquired with high precision, the conversion from the weak current signal to the voltage signal needs to be realized. The current-voltage conversion circuit is generally 2 types, one type is a sampling resistor type current-voltage conversion circuit, the circuit needs that the internal resistance of a photodiode is far greater than that of a sampling resistor and is at least M omega level, and the internal resistance of the photodiode can rarely reach M omega level, so that the method is not suitable for the weak current signal acquisition of the nA level; secondly, a transimpedance amplifier using a high input impedance operational amplifier (operational amplifier) has the problem that the traditional transimpedance amplifying circuit has large noise and leakage current interference, so that the research on undistorted amplification and accurate detection of weak current signals is more needed.
In summary, the signal detection circuit of the conventional photodiode has a problem of distorted detection results.
Disclosure of Invention
In view of the above, the present utility model provides a weak current detection circuit for a photodiode, which solves the problem of distortion of detection results of a signal detection circuit of a conventional photodiode by improving circuit configuration.
In order to solve the technical problems, the technical scheme of the utility model is that a weak current detection circuit for a photodiode is adopted, the weak current detection circuit comprises a front-stage amplification circuit and a rear-stage amplification circuit which are sequentially cascaded, the front-stage amplification circuit is provided with a first operational amplifier, a first pin of the first operational amplifier is electrically connected with the rear-stage amplification circuit through a resistor, the first pin is reversely connected with a fourth pin of the first operational amplifier through a feedback resistor, a third pin of the first operational amplifier is grounded, and the fourth pin is electrically connected with an output end of the photodiode; the post-stage amplifying circuit is provided with a second operational amplifier, the second operational amplifier comprises a first channel and a second channel, wherein a first pin of the first channel is electrically connected with a fifth pin of the second channel through a filter circuit, the first pin of the first channel is reversely connected with a second pin of the first channel through a feedback resistor, a third pin of the first channel is electrically connected with a parallel circuit formed by the fifth resistor and a sixth resistor and is grounded, and a sixth pin of the second channel is electrically connected with a seventh pin.
Optionally, the weak current detection circuit further comprises a power supply circuit, wherein the power supply circuit comprises a first power supply circuit for outputting 2.5V voltage and a second power supply circuit for outputting-3.3V voltage.
Optionally, the first pin of the first power supply circuit is grounded, the second pin of the first power supply circuit is connected to the capacitor and grounded, the 2.5V power supply voltage output by the second pin of the first power supply circuit is transmitted to the fifth pin of the first operational amplifier, and the third pin of the first power supply circuit is electrically connected to an external power supply.
Optionally, the first pin of the second power supply circuit is grounded through a third capacitor, and the first pin of the second power supply circuit is electrically connected with the second pin of the first operational amplifier and the fourth pin of the second operational amplifier respectively; the second pin of the second power supply circuit is grounded; the third pin of the second power supply circuit is electrically connected with an external power supply and grounded through a fourth capacitor; and the fifth pin of the second power supply circuit is electrically connected with the sixth pin of the second power supply circuit through a fifth capacitor.
Optionally, the second pin of the first operational amplifier is electrically connected to the first pin of the second power supply circuit, and the second pin of the first operational amplifier is grounded through a sixth capacitor.
Optionally, the second pin of the first power supply circuit is electrically connected with the fifth pin of the first operational amplifier, and the fifth pin of the first operational amplifier is grounded through a parallel circuit formed by an eighth capacitor and a ninth capacitor.
Optionally, the fourth pin of the first channel is grounded through an eleventh capacitor and is electrically connected to the first pin of the second power supply circuit.
Optionally, the eighth pin of the second channel is grounded through a parallel circuit formed by the twelfth capacitor and the thirteenth capacitor, and is electrically connected with an external power supply.
Optionally, the eighth pin of the second channel is grounded through a parallel circuit formed by the twelfth capacitor and the thirteenth capacitor, and is electrically connected with an external power supply.
The primary improvement of the utility model is that the weak current detection circuit for the photodiode is provided, the noise of the operational amplifier is effectively reduced by constructing a high-precision operational amplifier with low voltage noise density, low current noise density, low bias current and low temperature drift, and the circuit is subjected to phase compensation by adding a feedback capacitor, so that the equivalent noise bandwidth on a feedback resistor is reduced, and the effect of inhibiting the circuit noise is achieved. Meanwhile, by adopting a front-back two-stage amplification mode and changing the value of a feedback resistor, the undistorted amplification and the accurate detection of the nA-mA level weak current signal are realized, and the problem of distortion of detection results of a traditional photodiode signal detection circuit is solved.
Drawings
FIG. 1 is a simplified circuit diagram of a weak current detection circuit for a photodiode of the present utility model;
FIG. 2 is a simplified circuit diagram of a first power supply circuit of the present utility model;
fig. 3 is a simplified circuit diagram of a second power supply circuit of the present utility model.
Detailed Description
In order to make the technical scheme of the present utility model better understood by those skilled in the art, the present utility model will be further described in detail with reference to the following specific embodiments.
As shown in fig. 1, a weak current detection circuit for a photodiode includes a pre-stage amplification circuit 1 and a post-stage amplification circuit 2 which are sequentially cascaded, wherein the pre-stage amplification circuit 1 is provided with a first operational amplifier, a first pin of the first operational amplifier is electrically connected with the post-stage amplification circuit 2 through a resistor R1, the first pin is reversely connected with a fourth pin of the first operational amplifier through a feedback resistor R2, a third pin of the first operational amplifier is grounded, and the fourth pin is electrically connected with an output end of the photodiode; the post-stage amplifying circuit 2 is provided with a second operational amplifier, the second operational amplifier comprises a first channel and a second channel, wherein a first pin of the first channel is electrically connected with a fifth pin of the second channel through a filter circuit, the first pin of the first channel is reversely connected with a second pin of the first channel through a feedback resistor R4, a third pin of the first channel is electrically connected with a parallel circuit formed by a fifth resistor R5 and a sixth resistor R6 and is grounded, and a sixth pin of the second channel is electrically connected with a seventh pin. The model of the first operational amplifier may be AD8691; the model of the second operational amplifier may be AD8666; the filter circuit is composed of a third resistor R3 and a tenth capacitor C10.
Further, the first pin of the first operational amplifier is the converted voltage outputAn end with an output voltage of V o1 The calculation formula is V o1 ＝I in ×R 2 Wherein I in The value of the weak current signal output by the photodiode; the fourth pin of the first operational amplifier is an inverting input end; the second pin of the first operational amplifier is a negative voltage power supply end; the third pin of the first operational amplifier is a non-inverting input end; the fifth pin of the first operational amplifier is a positive voltage power supply end.
Further, the first pin of the first channel is a voltage output end; the second pin of the first channel is an inverting input end; the third pin of the first channel is a non-inverting input end; the fourth pin of the first channel is a negative voltage input end; the fifth pin of the second channel is a non-inverting input end; the sixth pin of the second channel is an inverted input end; the seventh pin of the second channel is an output end, and the output voltage is V o2 The calculation formula isThe eighth pin of the second channel is a positive voltage supply terminal.
Further, the weak current detection circuit further comprises a power supply circuit, and the power supply circuit comprises a first power supply circuit for outputting 2.5V voltage and a second power supply circuit for outputting-3.3V voltage.
Further, as shown in fig. 2, the first pin of the first power supply circuit is grounded, the second pin of the first power supply circuit is connected to the capacitor C1 and grounded, the 2.5V power supply voltage output by the second pin of the first power supply circuit is transmitted to the fifth pin of the first operational amplifier, the third pin of the first power supply circuit is electrically connected to an external power supply, and the fourth pin of the first power supply circuit is suspended. The first power supply circuit can use a power conversion chip AMS1117-2.5.
Further, as shown in fig. 3, the first pin of the second power supply circuit is grounded through a third capacitor C3, and the first pin of the second power supply circuit is electrically connected to the second pin of the first operational amplifier and the fourth pin of the second operational amplifier, respectively; the second pin of the second power supply circuit is grounded; the third pin of the second power supply circuit is electrically connected with an external power supply and grounded through a fourth capacitor C4, and meanwhile, the third pin of the second power supply circuit is electrically connected with the fourth pin of the second power supply circuit at the enabling end; the fifth pin of the second power supply circuit is electrically connected with the sixth pin of the second power supply circuit through a fifth capacitor C5. Wherein, the second power supply circuit may use a power conversion chip LM2776.
Further, the second pin of the first operational amplifier is electrically connected to the first pin of the second power supply circuit, and the second pin of the first operational amplifier is grounded through a sixth capacitor C6.
Further, the second pin of the first power supply circuit is electrically connected to the fifth pin of the first operational amplifier, and the fifth pin of the first operational amplifier is grounded through a parallel circuit formed by an eighth capacitor C8 and a ninth capacitor C9.
Further, the fourth pin of the first channel is grounded through an eleventh capacitor C11 and is electrically connected to the first pin of the second power supply circuit.
Further, the eighth pin of the second channel is grounded through a parallel circuit formed by the twelfth capacitor C12 and the thirteenth capacitor C13, and is electrically connected to an external power source.
Further, two ends of the feedback resistor R2 are electrically connected to the feedback capacitor C7.
The utility model effectively reduces the noise of the operational amplifier by constructing the high-precision operational amplifier with low voltage noise density, low current noise density, low bias current and low temperature drift, and simultaneously performs phase compensation on the circuit by adding the feedback capacitor, reduces the equivalent noise bandwidth on the feedback resistor and plays a role in inhibiting the circuit noise. Meanwhile, by adopting a front-back two-stage amplification mode and changing the value of a feedback resistor, the undistorted amplification and the accurate detection of the nA-mA level weak current signal are realized, and the problem of distortion of detection results of a traditional photodiode signal detection circuit is solved. And the dual-channel rail-to-rail operational amplifier adopted by the rear-stage amplifying circuit greatly saves the PCB wiring space and the power consumption compared with the traditional discrete multi-stage amplifying circuit.
The weak current detection circuit for the photodiode provided by the embodiment of the utility model is provided. In the description, each embodiment is described in a progressive manner, and each embodiment is mainly described by the differences from other embodiments, so that the same similar parts among the embodiments are mutually referred. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the utility model can be made without departing from the principles of the utility model and these modifications and adaptations are intended to be within the scope of the utility model as defined in the following claims.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present utility model.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
Claims (9)
1. A weak current detection circuit for a photodiode is characterized by comprising a front-stage amplification circuit (1) and a rear-stage amplification circuit (2) which are sequentially cascaded,
the front-stage amplifying circuit (1) is provided with a first operational amplifier, a first pin of the first operational amplifier is electrically connected with the rear-stage amplifying circuit (2) through a resistor (R1), the first pin is reversely connected with a fourth pin of the first operational amplifier through a feedback resistor (R2), a third pin of the first operational amplifier is grounded, and the fourth pin is electrically connected with the output end of the photodiode;
the post-stage amplifying circuit (2) is provided with a second operational amplifier, the second operational amplifier comprises a first channel and a second channel, wherein a first pin of the first channel is electrically connected with a fifth pin of the second channel through a filter circuit, the first pin of the first channel is reversely connected with a second pin of the first channel through a feedback resistor (R4), a third pin of the first channel is electrically connected with a parallel circuit formed by a fifth resistor (R5) and a sixth resistor (R6) and grounded, and a sixth pin of the second channel is electrically connected with a seventh pin.
2. The weak current detection circuit of claim 1, further comprising a power supply circuit comprising a first power supply circuit for outputting a 2.5V voltage and a second power supply circuit for outputting a-3.3V voltage.
3. The weak current detection circuit according to claim 2, wherein a first pin of the first power supply circuit is grounded, a second pin of the first power supply circuit is connected to a capacitor (C1) and grounded, a 2.5V power supply voltage output from the second pin of the first power supply circuit is transmitted to a fifth pin of the first operational amplifier, and a third pin of the first power supply circuit is electrically connected to an external power supply.
4. A weak current detection circuit according to claim 3, wherein the first pin of the second power supply circuit is grounded via a third capacitor (C3), and the first pin of the second power supply circuit is electrically connected to the second pin of the first operational amplifier and the fourth pin of the second operational amplifier, respectively; the second pin of the second power supply circuit is grounded; the third pin of the second power supply circuit is electrically connected with an external power supply and grounded through a fourth capacitor (C4); the fifth pin of the second power supply circuit is electrically connected with the sixth pin of the second power supply circuit through a fifth capacitor (C5).
5. The weak current detection circuit according to claim 4, wherein the second pin of the first operational amplifier is electrically connected to the first pin of the second power supply circuit, and the second pin of the first operational amplifier is grounded via a sixth capacitor (C6).
6. A weak current detection circuit according to claim 3, wherein the second pin of the first power supply circuit is electrically connected to the fifth pin of the first operational amplifier, and the fifth pin of the first operational amplifier is grounded via a parallel circuit constituted by an eighth capacitor (C8) and a ninth capacitor (C9).
7. The weak current detection circuit according to claim 4, wherein the fourth pin of the first channel is grounded via an eleventh capacitor (C11) and is electrically connected to the first pin of the second power supply circuit.
8. The weak current detection circuit according to claim 4, wherein the eighth pin of the second channel is grounded via a parallel circuit constituted by a twelfth capacitance (C12) and a thirteenth capacitance (C13) and is electrically connected to an external power source.
9. The weak current detection circuit according to claim 1, wherein both ends of the feedback resistor (R2) are electrically connected to a feedback capacitor (C7).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320216909.5U CN219417649U (en) | 2023-02-13 | 2023-02-13 | Weak current detection circuit for photodiode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320216909.5U CN219417649U (en) | 2023-02-13 | 2023-02-13 | Weak current detection circuit for photodiode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219417649U true CN219417649U (en) | 2023-07-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320216909.5U Active CN219417649U (en) | 2023-02-13 | 2023-02-13 | Weak current detection circuit for photodiode |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN219417649U (en) |
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2023
- 2023-02-13 CN CN202320216909.5U patent/CN219417649U/en active Active
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