
Silicon Diode Temperature Sensor Working Principle
The working principle of silicon diode temperature sensor is based on the voltage-temperature characteristics of semiconductor PN junction (especially silicon diode).
The following is a detailed introduction to the working principle of silicon diode temperature sensor.
Basic principle of silicon diode temperature sensor
Silicon diode temperature sensor mainly uses the characteristic that the forward voltage of the PN junction of silicon diode changes with temperature to measure temperature. When the diode is forward biased, there is a certain relationship between its forward voltage (V_F) and temperature.
Under constant current conditions, as the temperature increases, the forward voltage of the diode decreases. This characteristic makes silicon diode an ideal element for making temperature sensors.
If you need to purchase IoT modules, please contact the IoT Cloud Platform Blog (blog.iotcloudplatform.com).
Silicon Diode Temperature Sensor Experiment Theory and Working Principle
Silicon Diode as a Temperature Sensor|Physics Lab Experiment |Theory and Working

Silicon Diode as a Temperature Sensor|Physics Lab Experiment
1. Forward voltage-temperature characteristics of PN junction
The PN junction is the core part of the semiconductor diode, which is formed by the contact between P-type semiconductor and N-type semiconductor. Under forward bias conditions, that is, when the P region is connected to the positive electrode and the N region is connected to the negative electrode, the depletion layer in the PN junction will become narrower, allowing the majority carriers (holes in the P region and electrons in the N region) to pass through the depletion layer more easily to form a forward current. At this time, the relationship between the forward voltage and temperature of the PN junction can be approximately expressed as:
V_F = V_T * ln(I_F / I_S)
Wherein, V_F is the forward voltage, V_T is the thermal voltage (related to temperature), I_F is the forward current, and I_S is the reverse saturation current (also related to temperature, but usually changes less). Since both V_T and I_S are related to temperature, the forward voltage V_F will also change with temperature. Under the condition of constant current I_F, as the temperature increases, V_T increases, but the change in I_S is relatively small, so V_F will decrease. This characteristic is the basis for the operation of silicon diode temperature sensors.
2. Temperature coefficient and linearity
The voltage-temperature characteristics of silicon diodes usually have a certain linearity. Within a certain temperature range, the relationship between the forward voltage V_F and the temperature T can be approximated as a linear relationship. The temperature coefficient (that is, the voltage change caused by a unit temperature change) is usually expressed as mV/°C or μV/°C. For silicon diodes, the temperature coefficient is generally around -2mV/°C (measured near 25°C). This means that when the temperature rises by 1°C, the forward voltage decreases by about 2mV. It should be noted that this temperature coefficient may vary depending on the specific type of diode, the manufacturing process, and the measurement conditions.
Implementation of Silicon Diode Temperature Sensor
Silicon diode temperature sensors can be implemented in a variety of ways, including analog output, digital output, and integrated temperature sensors. The following is a detailed introduction to these implementations.
1. Analog Output Silicon Diode Temperature Sensor
Analog output silicon diode temperature sensors usually directly use the voltage-temperature characteristics of the diode to measure temperature. By forward biasing the diode and measuring its forward voltage V_F, it is then converted to a temperature value based on a known temperature coefficient. In order to achieve higher accuracy and stability, the diode usually needs to be calibrated and temperature compensated. In addition, differential circuits or operational amplifiers can also be used to reduce noise interference and improve measurement accuracy.
2. Digital output silicon diode temperature sensor
Digital output silicon diode temperature sensor converts analog signal into digital signal for output. This usually involves steps such as amplifying the forward voltage V_F of the diode, filtering, analog-to-digital conversion (ADC). Digital output sensors have higher accuracy, stability and anti-interference ability, and are easy to interface and communicate with digital systems such as microprocessors and computers. In order to achieve higher accuracy and resolution, technical means such as high-resolution ADC, temperature compensation algorithm and calibration technology can be used.
3. Integrated temperature sensor
Integrated temperature sensor is a temperature sensor that integrates silicon diode and its auxiliary circuit on the same chip. This sensor has the advantages of small size, low cost, easy use, etc., and can achieve high accuracy and linear output. Integrated temperature sensors usually use differential circuits or bandgap references to improve accuracy and stability. In addition, functional modules such as temperature compensation circuits, amplifier circuits, and filter circuits can be added according to application requirements to achieve more complex functions and higher performance.
Application of Silicon Diode Temperature Sensors
Silicon diode temperature sensors are widely used in various fields, including industrial control, automotive electronics, consumer electronics, aerospace, etc. The following is a detailed introduction to their applications.
1. Industrial Control
In the field of industrial control, silicon diode temperature sensors are often used to monitor the temperature status of machinery and equipment to prevent overheating damage or fault warning. For example, installing temperature sensors in the cooling system of equipment such as motors, transformers, and power supplies can monitor their temperature in real time and control the speed of the cooling fan or start the alarm system to protect the safe operation of the equipment. In addition, in industrial automation production lines, temperature sensors are also often used to monitor parameters such as material temperature and ambient temperature to control the stability and efficiency of the production process.
2. Automotive Electronics
In the field of automotive electronics, silicon diode temperature sensors are often used in engine cooling systems, battery management systems, and air conditioning systems. For example, installing a temperature sensor in the engine cooling system can monitor the coolant temperature in real time and control the speed of the cooling fan to keep the engine running within the normal operating temperature range; using a temperature sensor in the battery management system can monitor the temperature status of the battery to prevent performance degradation or safety issues caused by overheating or low temperature; using a temperature sensor in the air conditioning system can monitor the temperature in the car in real time and adjust the output of the air conditioning system according to passenger needs to provide a comfortable riding environment.
3. Consumer electronics
In the field of consumer electronics, silicon diode temperature sensors are often used in the thermal management systems of devices such as smartphones, tablets, and laptops. These devices generate a lot of heat during operation, which may cause performance degradation or damage if not dissipated in time. Therefore, installing temperature sensors in these devices can monitor their temperature in real time and start the heat dissipation mechanism (such as fans, heat sinks, etc.) as needed to keep the device running within the normal operating temperature range. In addition, in some high-end consumer electronic products (such as smart wearable devices, smart home devices, etc.), temperature sensors are also used to monitor parameters such as user body temperature or ambient temperature to achieve more intelligent functions and services.
4. Aerospace
In the field of aerospace, silicon diode temperature sensors are often used to monitor the temperature status of aircraft, rockets and other aircraft to ensure their safe operation. For example, installing temperature sensors in key parts such as engines, fuel tanks, and wings can monitor their temperatures in real time and start cooling mechanisms or adjust flight attitudes as needed to prevent performance degradation or safety issues caused by overheating. In addition, in some high-end aerospace equipment (such as satellites, space stations, etc.), temperature sensors are also used to monitor the temperature environment inside the equipment to ensure its normal operation and long-term stability.
Advantages and Disadvantages of Silicon Diode Temperature Sensors
Silicon diode temperature sensors have some significant advantages and disadvantages. The following is a detailed introduction to their advantages and disadvantages.
Advantages:
- High Precision: Silicon diode temperature sensors have high precision and stability and can meet various high-precision measurement needs.
- Wide Temperature Measurement Range: Silicon diode temperature sensors can measure in a wide temperature range and are suitable for temperature monitoring in various high or low temperature environments.
- Small Size: Silicon diode temperature sensors are small in size and light in weight, making them easy to install and use.
- Low Cost: Silicon diode temperature sensors have low manufacturing costs and are easy to mass produce and apply.
- Good long-term stability: Silicon diode temperature sensors have good long-term stability and reliability, and can operate stably for a long time in harsh environments.
Disadvantages:
- Nonlinearity: Although the voltage-temperature characteristics of silicon diode temperature sensors are linear within a certain range, nonlinear deviations may occur at extreme temperatures. This requires calibration and compensation techniques to reduce errors.
- Limited sensitivity: The sensitivity of silicon diode temperature sensors is limited by their physical properties and manufacturing processes, and may not meet some extremely high-precision or extremely fast-response measurement requirements.
- Susceptible to interference: Silicon diode temperature sensors may be affected by external factors such as electromagnetic interference and thermal noise during measurement, resulting in increased measurement errors. Therefore, corresponding shielding and filtering measures need to be taken to improve anti-interference capabilities.
- Calibration required: In order to improve measurement accuracy and stability, silicon diode temperature sensors usually require regular calibration and temperature compensation to ensure that their performance meets the requirements.
Conclusion and Prospect
As a temperature sensor based on the voltage-temperature characteristics of semiconductor PN junction, silicon diode temperature sensor has the advantages of high precision, wide temperature measurement range, small size, low cost and good long-term stability.
It has been widely used in industrial control, automotive electronics, consumer electronics, aerospace and other fields. However, silicon diode temperature sensor also has some disadvantages, such as nonlinearity, limited sensitivity, susceptibility to interference and the need for calibration.
In order to overcome these shortcomings and further improve its performance and application scope, future research directions may include the following aspects:
- New materials and technologies: Explore new semiconductor materials (such as silicon carbide, gallium nitride, etc.) and new manufacturing processes and technologies to improve the sensitivity and accuracy of temperature sensors.
- Intelligence and networking: Combine temperature sensors with microprocessors, sensor networks and other technologies to realize intelligent and networked functions, so as to better meet the needs of various complex application scenarios.
- Miniaturization and integration: Further reduce the size and weight of temperature sensors, and integrate them with other sensors or actuators to achieve more compact and efficient system design.
- Adaptive calibration and compensation: Develop adaptive calibration and compensation algorithms to automatically adjust the parameters and performance of temperature sensors to cope with changes in different environments and application conditions.
In summary, silicon diode temperature sensors, as an important type of temperature sensor, play an important role in various fields.
With the advancement of science and technology and the in-depth development of applications, silicon diode temperature sensors will develop towards higher accuracy, higher sensitivity, smaller size, and more intelligent and networked in the future to meet the needs of various complex application scenarios.
About IoT Cloud Platform
IOT Cloud Platform (blog.iotcloudplatform.com) focuses on IOT solutions, smart homes, new materials for the Internet of Things, IoT design, security Internet of Things, industrial IOT, military Internet of Things, IOT modules, VR/AR, chips, semiconductors, embedded development, smart cities, smart agricultural factories, robots, smart hardware, new energy, photovoltaic solar energy, lithium batteries, RFID and other scientific and technological knowledge and product sales. At the same time, the Internet of Things Cloud Platform provides advertising alliance services for global users, welcome to consult.
FAQs
The following are common questions and answers about silicon diode temperature sensors:
A silicon diode is a diode made of silicon material. It is a semiconductor device composed of two semiconductor materials, P-type and N-type, and has unidirectional conductivity.
This unidirectional conductivity is achieved by contacting P-type and N-type semiconductors to form a PN junction. When the PN junction is forward biased, the diode is in the on state; when the PN junction is reverse biased, the diode is in the off state. Silicon diodes play an important role in electronic engineering due to their unique electrical properties and wide range of applications.
The working principle of silicon diode temperature sensors is to use the relationship between the forward voltage of the PN junction and temperature. Under constant current conditions, the base-emitter voltage (VBE) of the silicon diode shows an approximately linear relationship with the temperature. As the temperature rises, the VBE will decrease, and this rate of change is relatively constant. By measuring the change in VBE, the temperature can be detected.
Silicon diode temperature sensors have the advantages of high precision, high stability, small size, low cost, good linearity, and fast response speed. In addition, because it is made of silicon materials, it has good compatibility with integrated circuits and is easy to integrate and digitally process. It is suitable for various industrial control occasions.
Common faults of silicon diode temperature sensors include inaccurate readings, slow response time, unstable output signals, etc. These faults may be caused by sensor aging, dirt accumulation, environmental interference, improper calibration, electromagnetic interference, or unstable power supply.
When dealing with a fault in a silicon diode temperature sensor, you can take the following measures: clean the sensor to remove dirt and dust; check and recalibrate the sensor to ensure accuracy; optimize the sensor’s mounting position to shorten the response time; use shielded cables to reduce electromagnetic interference; ensure a stable power supply to avoid unstable output signals, etc. If the fault cannot be eliminated, the sensor may need to be replaced.
The cause of inaccurate readings from a silicon diode temperature sensor could be sensor aging, dirt accumulation, environmental interference, or improper calibration, etc.
The cause of a slow response time from a silicon diode temperature sensor could be the sensor’s thermal inertia, material properties, or improper mounting position, etc.
The service life of a silicon diode temperature sensor depends on a variety of factors, such as the use environment, working conditions, and maintenance. Under normal circumstances, if the sensor is properly maintained and cared for, its service life can be relatively long. However, if the sensor is exposed to extreme conditions for a long time or is subject to adverse factors such as frequent thermal cycling, chemical corrosion, etc., its service life may be shortened.
In order to extend the service life of silicon diode temperature sensors, the following measures can be taken: select sensor types and specifications suitable for specific application scenarios; ensure that the sensor is used within the specified working range; regularly clean and maintain the sensor; avoid long-term exposure of the sensor to extreme environments; minimize the number of thermal cycles to reduce the effects of wear and corrosion, etc.
Silicon diode temperature sensors are mainly used in industrial control for temperature measurement, temperature control, temperature monitoring, etc., such as motor temperature monitoring, equipment overheating protection, ambient temperature control, etc.
To deal with inaccurate readings of silicon diode temperature sensors, you can clean the sensor, check and recalibrate, and replace the sensor if necessary.
To improve the response time of silicon diode temperature sensors, you can choose sensors with faster response times or optimize the installation location of the sensor.
To prevent silicon diode temperature sensor failure in industrial control, you can take measures such as regular maintenance, sensor calibration, ensuring that the sensor is properly installed according to the manufacturer’s instructions, and avoiding overload, shock or improper use.
Silicon diode temperature sensors have higher accuracy and stability than other temperature sensors such as thermocouples, and they also have faster response speeds. However, the cost of silicon diode temperature sensors may be relatively high, and the measurement range may be limited. When choosing, you need to weigh it based on the specific application requirements and budget.
Silicon diode temperature sensors are mainly used in automotive electronics to detect the temperature of the engine, intake gas, fuel, and inside and outside the car, providing temperature data for the car’s electronic control system to help the system achieve more precise control and regulation.
Silicon diode temperature sensors are usually installed in the engine compartment, such as the intake manifold, exhaust manifold, water tank, etc., as well as locations where temperature needs to be monitored inside and outside the car.
Possible faults of silicon diode temperature sensors in automotive electronics include inaccurate readings, unstable signals, and long response times. These faults may be caused by factors such as sensor aging, dirt accumulation, electromagnetic interference, or power supply problems.
When diagnosing silicon diode temperature sensor failures, you can use a dedicated diagnostic tool to read the sensor data and compare it with the actual temperature. At the same time, check whether the sensor’s connection lines, power supply, and grounding are normal, and whether there are problems such as electromagnetic interference.
Silicon diode temperature sensor failures may cause the automotive electronic control system to be unable to accurately obtain temperature data, thereby affecting the control and regulation accuracy of the system. For example, when the engine temperature is too high, if the sensor failure fails to alarm in time, it may cause engine damage.
Methods to prevent silicon diode temperature sensor failures include regular cleaning of sensors, checking connection lines and power supplies, and avoiding electromagnetic interference. At the same time, choosing high-quality sensors and suitable installation locations can also reduce the failure rate.
The replacement cycle of silicon diode temperature sensors varies depending on the model and the environment in which they are used. Generally speaking, if the sensor is working properly and there are no signs of failure, it does not need to be replaced regularly. However, if the sensor is aging, damaged, or has performance degradation, it should be replaced in a timely manner. For specific replacement cycles, it is recommended to refer to the car manufacturer’s maintenance manual or consult a professional technician.
Silicon diode temperature sensors are mainly used in consumer electronics to monitor and control the temperature of equipment to ensure that the equipment operates within a safe temperature range and prevent overheating damage.
Silicon diode temperature sensors have the advantages of high precision, high stability, low power consumption, and small size, which are very suitable for the requirements of consumer electronics products for temperature sensors.
Silicon diode temperature sensors are commonly used in battery temperature monitoring, CPU temperature control, ambient temperature sensing, etc. for consumer electronics such as smartphones, tablets, laptops, cameras, etc.
Possible faults of silicon diode temperature sensors in consumer electronics include inaccurate readings, slow response speed, unstable signals, etc. These faults may be caused by sensor aging, dirt accumulation, environmental interference or improper calibration.
To solve the problem of inaccurate readings of silicon diode temperature sensors, you can try to clean the sensor surface, recalibrate the sensor, or replace the sensor with a new one.
The response time of silicon diode temperature sensors is affected by factors such as the thermal inertia, material properties and packaging method of the sensor. Choosing sensors with faster response times and optimizing packaging methods can shorten the response time.
The service life of silicon diode temperature sensors depends on many factors, such as working environment, frequency of use, sensor quality, etc. Under normal use, the service life of silicon diode temperature sensors is usually longer, but the specific life depends on the actual application.
To extend the service life of silicon diode temperature sensors in consumer electronics, measures such as regular maintenance, sensor calibration, avoiding exposure of sensors to extreme environments, and correct use and installation of sensors according to the manufacturer’s instructions can be taken.
Silicon diode temperature sensors have good compatibility in consumer electronics and can be connected to various control systems and display devices to achieve real-time monitoring and control of temperature data.
The cost of silicon diode temperature sensors varies depending on factors such as brand, model, and quality. Generally speaking, high-precision and high-stability silicon diode temperature sensors are relatively expensive, but they can meet the strict requirements of consumer electronics products for temperature sensors. When choosing, you need to weigh the actual application needs and budget.