Circuit for measuring temperature of photodiode
By designing a photodiode temperature measurement circuit, using bias voltage and constant current source to alternately control the photodiode state, and combining a transimpedance amplifier and an analog-to-digital converter to collect voltage data, the problems of large space occupation and inconvenient assembly of the photodiode temperature measurement method are solved, and real-time temperature measurement of the photodiode and the normal operation of the photoelectric detection function are achieved, adapting to the miniaturization development of equipment.
Patent Information
- Application Number
- CN202422565077.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-23
- Publication Date
- 2025-10-03
- Estimated Expiration
- 2034-10-23
AI Technical Summary
The existing photodiode temperature measurement method occupies a large space, is inconvenient to assemble and difficult to integrate, which affects the miniaturization development of the equipment.
A circuit for measuring the temperature of a photodiode is designed. Through a bias voltage circuit, a constant current source, a sampling circuit, and a main control unit, real-time temperature measurement of the photodiode is achieved without the need for an additional temperature sensor. The bias voltage circuit and the constant current source are used to alternately control the state of the photodiode. Voltage data is collected and processed in combination with a transimpedance amplifier, a buffer circuit, and an analog-to-digital converter.
The real-time temperature measurement of the photodiode and the normal operation of the photoelectric detection function are realized, the assembly difficulty is reduced, and the miniaturization demand of the equipment is adapted.
Smart Images
Figure CN223412832U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of photodiodes, in particular to a circuit for measuring the temperature of a photodiode. Background Art
[0002] A photodiode is a light detector that can convert light into a current or voltage signal depending on how it is used. Photodiodes are commonly used in various light detection devices, such as laser cloud meters based on lidar. In such devices, the stability of the photodiode directly affects the overall performance of the device. The temperature of the photodiode will gradually rise during operation, and the photodiode itself is very sensitive to temperature. When the temperature rises, the accuracy will decrease. Therefore, it is necessary to grasp the temperature of the photodiode in real time. In the prior art, a common practice is to set a temperature sensor on the side of the photodiode for temperature measurement. However, as electronic products have been developing in the direction of integration and miniaturization, the disadvantages of this measurement method have become increasingly obvious, namely, it takes up a lot of space, is inconvenient to assemble, and is difficult to integrate. Utility Model Content
[0003] In order to address the deficiencies in the prior art, the utility model provides a circuit for measuring the temperature of a photodiode, which can grasp the operating status of the photodiode and does not require an additional temperature sensor to be set next to the photodiode, effectively reducing the difficulty of assembly.
[0004] In order to achieve the above object, the specific solution adopted by the present invention is: a circuit for measuring the temperature of a photodiode, comprising:
[0005] A bias voltage circuit, used for applying a bias voltage to the photodiode to put the photodiode in a photodetection state, the bias voltage circuit comprising a negative voltage generating circuit P1 and an electronic switch S1 for controlling the conduction state between the negative voltage generating circuit P1 and the photodiode;
[0006] The constant current source P2 is used to provide a stable current to the photodiode so that the photodiode is in a temperature measurement state;
[0007] a sampling circuit, configured to collect first voltage data of the photodiode when the photodiode is in a photodetection state, or collect second voltage data of the photodiode when the photodiode is in a temperature measurement state;
[0008] The main control unit M1 is configured to calculate the real-time temperature of the photodiode according to the second voltage data.
[0009] As a further optimization of the above-mentioned circuit for measuring the temperature of a photodiode: the sampling circuit includes a transimpedance amplifier OP1, a buffer circuit B1 and an analog-to-digital converter AD1, the transimpedance amplifier OP1 and the analog-to-digital converter AD1 are used in conjunction with each other to collect the first voltage data of the photodiode when the photodiode is in a photodetection state, the buffer circuit B1 and the analog-to-digital converter AD1 are used in conjunction with each other to collect the second voltage data of the photodiode when the photodiode is in a temperature measurement state, and the analog-to-digital converter AD1 is electrically connected to the main control unit M1.
[0010] As a further optimization of the above circuit for measuring the temperature of a photodiode: the sampling circuit includes an electronic switch S2, and the electronic switch S2 is used to control the conduction state of the transimpedance amplifier OP1.
[0011] As a further optimization of the above circuit for measuring photodiode temperature: the sampling circuit includes an electronic switch S3, which is used to control the conduction between the transimpedance amplifier OP1 and the analog-to-digital converter AD1 or the conduction between the buffer circuit B1 and the analog-to-digital converter AD1.
[0012] As a further optimization of the above-mentioned circuit for measuring the temperature of a photodiode: the electronic switch S1 and the electronic switch S2 are set as CMOS single-pole single-throw switches, the electronic switch S3 is set as a CMOS single-pole double-throw switch, and the electronic switch S1, the electronic switch S2 and the electronic switch S3 are all electrically connected to the main control unit M1.
[0013] As a further optimization of the above-mentioned circuit for measuring the temperature of a photodiode: the negative voltage generating circuit P1 is electrically connected to the main control unit M1, and the main control unit M1 is further used to control the bias voltage output by the negative voltage generating circuit P1 according to the real-time temperature.
[0014] As a further optimization of the above-mentioned circuit for measuring the temperature of a photodiode: the bias voltage circuit periodically applies a bias voltage to the photodiode, so that the photodiode is alternately in a photodetection state and a temperature measurement state.
[0015] As a further optimization of the above circuit for measuring the temperature of a photodiode: the constant current source P2 includes an operational amplifier and a differential amplifier that are electrically connected.
[0016] Beneficial effects: The utility model can change the state of the photodiode so that the photodiode can perform photoelectric detection normally, and can also accurately measure the real-time temperature of the photodiode, which not only ensures that the operating state of the photodiode can be mastered, but also does not require an additional temperature sensor to be set next to the photodiode, effectively reducing the difficulty of assembly. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is the overall structural diagram of the utility model;
[0018] Figure 2 This is the schematic diagram of the constant current source P2;
[0019] Figure 3 This is the schematic diagram of analog-to-digital converter AD1;
[0020] Figure 4 It is a schematic diagram of the time control method of the photoelectric detection stage and the temperature measurement stage. DETAILED DESCRIPTION
[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0022] See also Figure 1 , a circuit for measuring the temperature of a photodiode, including a bias voltage circuit, a constant current source P2, a sampling circuit and a main control unit M1.
[0023] The bias voltage circuit is used to apply a bias voltage to the photodiode to put the photodiode in a photodetection state. The bias voltage circuit includes a negative voltage generating circuit P1 and an electronic switch S1 for controlling the conduction state between the negative voltage generating circuit P1 and the photodiode.
[0024] The constant current source P2 is used to provide a stable current to the photodiode so that the photodiode is in a temperature measurement state.
[0025] The sampling circuit is used to collect first voltage data of the photodiode when the photodiode is in a photodetection state, or to collect second voltage data of the photodiode when the photodiode is in a temperature measurement state.
[0026] The main control unit M1 is configured to calculate the real-time temperature of the photodiode according to the second voltage data.
[0027] When the present invention is in use, if the photodiode is required to realize the function of photoelectric sensing, the main control unit M1 controls the bias voltage circuit to apply a bias voltage to the photodiode, so that the photodiode is in a photoelectric detection state, and the sampling circuit collects the first voltage data of the photodiode and transmits it to the main control unit M1. The main control unit M1 processes the first voltage data to obtain the required light data; if the temperature of the photodiode needs to be measured, the main control unit M1 controls the bias voltage circuit to be disconnected, and only uses the constant current source P2 to provide a stable current to the photodiode. The sampling circuit collects the second voltage data of the photodiode and transmits it to the main control unit M1. The main control unit M1 analyzes and processes the second voltage data, and compares it with the reference voltage of the photodiode in the calibration state. The voltage difference can be calculated, and then the real-time temperature of the photodiode can be calculated in combination with the temperature characteristics of the photodiode itself.
[0028] The utility model can change the state of the photodiode so that the photodiode can perform photoelectric detection normally, and can also accurately measure the real-time temperature of the photodiode, which not only ensures that the operating state of the photodiode can be mastered, but also does not need to set up an additional temperature sensor next to the photodiode, effectively reducing the difficulty of assembly.
[0029] Because the sampling circuit needs to collect the electrical signal from the photodiode regardless of whether the photodiode is in the photodetection state or the temperature measurement state, to better achieve sampling of the electrical signal in different states, the sampling circuit includes a transimpedance amplifier OP1, a buffer circuit B1, and an analog-to-digital converter AD1. The transimpedance amplifier OP1 and the analog-to-digital converter AD1 cooperate to collect first voltage data of the photodiode when the photodiode is in the photodetection state, and the buffer circuit B1 and the analog-to-digital converter AD1 cooperate to collect second voltage data of the photodiode when the photodiode is in the temperature measurement state. The analog-to-digital converter AD1 is electrically connected to the main control unit M1. The transimpedance amplifier OP1 is used to collect a first analog signal from the photodiode, the buffer circuit B1 is used to collect a second analog signal from the photodiode, and the analog-to-digital converter AD1 is used to convert the first analog signal to obtain first voltage data in the form of a digital signal, and to convert the second analog signal to obtain second voltage data in the form of a digital signal. The first and second voltage data are collected independently, and the transimpedance amplifier OP1 and the buffer circuit B1 can be adaptively adjusted according to the numerical range of the first and second voltage data to fully improve the collection accuracy.
[0030] On the basis of setting up a transimpedance amplifier OP1 and a buffer circuit B1 to respectively collect the first voltage data and the second voltage data, in order to more accurately control the two sampling processes, the sampling circuit includes an electronic switch S2 and an electronic switch S3. The electronic switch S2 is used to control the conduction state of the transimpedance amplifier OP1, and the electronic switch S3 is used to control the conduction state between the transimpedance amplifier OP1 and the analog-to-digital converter AD1, or the conduction state between the buffer circuit B1 and the analog-to-digital converter AD1. By setting up the electronic switches S2 and S3, when the photodiode is in the temperature measurement state, the transimpedance amplifier OP1 can be disconnected by the electronic switch S2, and the electronic switch S3 can be switched to a state connecting the buffer circuit B1 to the analog-to-digital converter AD1, so that the transimpedance amplifier OP1 does not affect the collection and transmission of the second voltage data; when the photodiode is in the photodetection state, the transimpedance amplifier OP1 is turned on by the electronic switch S2, and the electronic switch S3 is switched to a state connecting the transimpedance amplifier OP1 to the analog-to-digital converter AD1. Because the constant current source P2 provides a stable current to the photodiode, the constant current source P2 is always running regardless of whether the photodiode is in the temperature measurement state or the photodetection state, and therefore the buffer circuit B1 does not need to be disconnected.
[0031] Accordingly, to achieve the above-mentioned functions, electronic switches S1 and S2 are configured as CMOS single-pole single-throw switches, and electronic switch S3 is configured as a CMOS single-pole double-throw switch. Electronic switches S1, S2, and S3 are all electrically connected to the main control unit M1. In one embodiment of the present invention, electronic switch S1 is comprised of the integrated circuit ADG602 and peripheral components. Closing electronic switch S1 places the photodiode in a photodetection state. Electronic switch S2 is comprised of the integrated circuit ADG1201BRJZ and peripheral components. When closed, it has an internal 120Ω on-resistance, which serves as the feedback resistor for the transimpedance amplifier OP1. When the photodiode is in the photodetection state, electronic switch S2 is closed, causing the transimpedance amplifier OP1 to operate in a closed-loop amplification state. When the photodiode is in the temperature measurement state, electronic switch S2 is opened, causing the transimpedance amplifier OP1 to operate in an open-loop state. Electronic switch S3 is comprised of the integrated circuit ADG719BRT and peripheral components. It has two independent channels, and switching to different channels changes the connection state of the analog-to-digital converter AD1.
[0032] See also Figure 2 and 3In addition to the three electronic switches, in this embodiment, the negative voltage generating circuit P1 is composed of the integrated circuit LT3093 and peripheral components. The circuit can stably output a maximum current of 200mA. The output voltage can be configured by changing the SET resistor parameter. In addition, the Ilim resistor can also be set. The constant current source P2 includes an electrically connected operational amplifier and a differential amplifier, wherein the differential amplifier model is INA597ID. In addition, it also includes matching resistors. By adjusting the resistance values of the matching resistors R1 and R2, the output current can be flexibly adjusted to meet different measurement requirements. The current limiting analog-to-digital converter AD1 is composed of the integrated circuit AD7942 and peripheral components; transimpedance amplifier OP1 is composed of an operational amplifier OPA2301AID and peripheral components. The voltage converted by transimpedance amplifier OP1 is Vout = I*Rf, where I is the input current value of the op amp and Rf is the resistance of the feedback resistor, i.e., the resistance of the on-resistance in the electronic switch S2; buffer circuit B1 is mainly composed of the operational amplifier OPA2301AID and peripheral components, and the circuit form is a voltage follower composed of op amps; analog-to-digital converter AD1 is composed of the integrated circuit AD7942 and peripheral components; main control unit M1 is composed of a single-chip microcomputer and peripheral components, and the single-chip microcomputer can adopt ARM architecture. The specific design form and principle of each peripheral component are conventional in the art and will not be elaborated here.
[0033] Considering that the characteristics of a photodiode change as its temperature rises, the photodiode's photodetection state can be adjusted based on the photodiode's temperature after measuring the photodiode's temperature. Specifically, the negative voltage generating circuit P1 is electrically connected to the main control unit M1, which is also used to control the bias voltage output by the negative voltage generating circuit P1 based on the real-time temperature. By changing the photodiode's bias voltage based on the photodiode's temperature, the photodiode's gain state can be adjusted, thereby ensuring the desired sensitivity of the photodiode.
[0034] See also Figure 4 Furthermore, the bias voltage circuit periodically applies a bias voltage to the photodiode, causing the photodiode to alternate between a photodetection state and a temperature measurement state. By alternating between the photodetection state and the temperature measurement state, the photodiode can be precisely adjusted based on its temperature. The duration of the photodetection state and the temperature measurement state can also be controlled to avoid interfering with the photodiode's photodetection process.
[0035] The present invention can be applied to various devices that require the use of photodiodes. For example, when the present invention is applied to a laser ceilometer, the photodiode to be measured is the avalanche photodiode in the laser ceilometer. During the process of detecting cloud height by the laser ceilometer, the temperature of the avalanche photodiode is dynamically measured, and the avalanche photodiode is controlled based on the temperature of the avalanche photodiode to ensure high-precision detection of cloud height.
[0036] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A circuit for measuring the temperature of a photodiode, characterized in that: include: A bias voltage circuit, used for applying a bias voltage to the photodiode to put the photodiode in a photodetection state, the bias voltage circuit comprising a negative voltage generating circuit P1 and an electronic switch S1 for controlling the conduction state between the negative voltage generating circuit P1 and the photodiode; The constant current source P2 is used to provide a stable current to the photodiode so that the photodiode is in a temperature measurement state; a sampling circuit, configured to collect first voltage data of the photodiode when the photodiode is in a photodetection state, or collect second voltage data of the photodiode when the photodiode is in a temperature measurement state; The main control unit M1 is configured to calculate the real-time temperature of the photodiode according to the second voltage data.
2. A circuit for measuring the temperature of a photodiode according to claim 1, characterized in that: The sampling circuit includes a transimpedance amplifier OP1, a buffer circuit B1 and an analog-to-digital converter AD1. The transimpedance amplifier OP1 and the analog-to-digital converter AD1 are used together to collect the first voltage data of the photodiode when the photodiode is in a photodetection state. The buffer circuit B1 and the analog-to-digital converter AD1 are used together to collect the second voltage data of the photodiode when the photodiode is in a temperature measurement state. The analog-to-digital converter AD1 is electrically connected to the main control unit M1.
3. A circuit for measuring the temperature of a photodiode according to claim 2, characterized in that: The sampling circuit includes an electronic switch S2 , and the electronic switch S2 is used to control the conduction state of the transimpedance amplifier OP1 .
4. A circuit for measuring the temperature of a photodiode according to claim 3, characterized in that: The sampling circuit includes an electronic switch S3, which is used to control the conduction between the transimpedance amplifier OP1 and the analog-to-digital converter AD1 or the conduction between the buffer circuit B1 and the analog-to-digital converter AD1.
5. A circuit for measuring the temperature of a photodiode according to claim 4, characterized in that: The electronic switch S1 and the electronic switch S2 are configured as CMOS single-pole single-throw switches, and the electronic switch S3 is configured as a CMOS single-pole double-throw switch. The electronic switches S1, S2 and S3 are all electrically connected to the main control unit M1.
6. A circuit for measuring the temperature of a photodiode according to claim 1, characterized in that: The negative pressure generating circuit P1 is electrically connected to the main control unit M1 , and the main control unit M1 is further configured to control the bias voltage output by the negative pressure generating circuit P1 according to the real-time temperature.
7. A circuit for measuring the temperature of a photodiode according to claim 1, characterized in that: The bias voltage circuit periodically applies a bias voltage to the photodiode, so that the photodiode is alternately in a photodetection state and a temperature measurement state.
8. The circuit for measuring the temperature of a photodiode according to claim 1, wherein: The constant current source P2 includes an operational amplifier and a differential amplifier that are electrically connected.