Temperature sensor and electronic equipment

Abstract

The invention provides a temperature sensor and electronic equipment, and belongs to the technical field of electronic equipment. The temperature sensor comprises a temperature detection unit and an analog-to-digital conversion unit, the temperature detection unit is connected with the analog-to-digital conversion unit, the analog-to-digital conversion unit comprises a successive approximation register SAR, the digit of the SAR is N, and N is a positive integer greater than 8; the temperature detection unit is used for generating a reference voltage and a temperature detection voltage and outputting the reference voltage and the temperature detection voltage to the analog-to-digital conversion unit, and the temperature detection voltage is in positive correlation with the currently detected temperature; and the analog-to-digital conversion unit is used for adjusting the reference voltage for N times based on the temperature detection voltage, adjusting numerical values on N digits of the SAR according to a sequence from high order to low order based on the magnitude relationship between the reference voltage after N times of adjustment and the temperature detection voltage, and obtaining and outputting a target numerical value sequence. According to the temperature sensor, the register with higher order is adopted, and the measured temperature precision is higher.

Description

Technical Field

[0001] This application relates to the field of electronic equipment technology, and in particular to a temperature sensor and electronic equipment. Background Technology

[0002] The accuracy of temperature sensors is crucial for the stable operation of display chips. Display chips generate a significant amount of heat during operation; inaccurate temperature control can lead to performance fluctuations, abnormal image display, and even hardware damage. High-precision temperature sensor detection enables more timely and refined thermal management, helping the system dynamically adjust power consumption and heat dissipation strategies. This ensures the display chip operates stably and reliably for extended periods at high performance, while simultaneously improving its energy efficiency and reliability.

[0003] Currently available temperature sensors typically have an 8-bit accuracy, meaning they can only quantify temperature changes into 256 levels. This makes it difficult to capture minute temperature fluctuations across the entire temperature range, often achieving only ±1℃ or even lower measurement accuracy. This coarse-grained detection capability cannot meet the temperature control requirements of display chips, causing the system to be unable to respond promptly to minute temperature drifts. Consequently, it affects brightness uniformity and color accuracy, limiting its application in high-end precision display fields. Therefore, there is an urgent need for a high-precision temperature sensor. Summary of the Invention

[0004] This application provides a temperature sensor and electronic device. The temperature sensor uses a higher-order register, resulting in higher temperature measurement accuracy. The technical solution is as follows: In a first aspect, a temperature sensor, a temperature detection unit, and an analog-to-digital conversion unit are provided. The temperature detection unit is connected to the analog-to-digital conversion unit, and the analog-to-digital conversion unit includes a SAR (Successive Approximation Register), wherein the SAR has N bits, and N is a positive integer greater than 8. The temperature detection unit is used to generate a reference voltage and a temperature detection voltage, and outputs the reference voltage and the temperature detection voltage to the analog-to-digital conversion unit. The temperature detection voltage is positively correlated with the currently detected temperature. The analog-to-digital conversion unit is used to adjust the reference voltage N times based on the temperature detection voltage, and based on the relationship between the reference voltage after N adjustments and the temperature detection voltage, adjust the values ​​of the N bits of the SAR in order from the high bit to the low bit to obtain and output the target value sequence, which is composed of the N values ​​of the SAR from the high bit to the low bit.

[0005] In a second aspect, an electronic device is provided, the electronic device including the temperature sensor described in the first aspect.

[0006] The beneficial effects of the technical solutions provided in this application are: The temperature sensor provided in this application includes a temperature detection unit and an analog-to-digital converter (ADC). The ADC includes a SAR (Specific Angle and Value Separator), which has N bits, where N is a positive integer greater than 8. The temperature measurement process using this sensor is as follows: the temperature detection unit generates a reference voltage and a temperature detection voltage, and outputs both to the ADC. Based on the temperature detection voltage, the ADC adjusts the reference voltage N times. Based on the relationship between the adjusted reference voltage and the temperature detection voltage, it adjusts the values ​​of the N bits of the SAR in descending order of bit position to obtain a target value sequence, which is then output. This target value sequence consists of the N values ​​of the SAR from the highest to the lowest bit position. The temperature detection voltage is positively correlated with the currently detected temperature and reflects the current ambient temperature. The number of times the reference voltage is adjusted is related to the number of bits in the SAR; the more bits the SAR has, the more times the reference voltage is adjusted. Each adjustment brings the reference voltage closer to the temperature detection voltage. The more times the reference voltage is adjusted, the closer the adjusted reference voltage is to the temperature detection voltage, and the more accurate the temperature measurement by the temperature sensor. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the structure of a temperature sensor provided in an embodiment of this application; Figure 2 This is a schematic diagram of the circuit structure of a subtractor provided in an embodiment of this application; Figure 3 This is a schematic diagram of the circuit structure of another subtractor provided in an embodiment of this application; Figure 4 This application provides an embodiment of the structure of the input terminal of a digital-to-analog converter; Figure 5 This is a schematic diagram of the input terminal of a digital-to-analog converter provided in an embodiment of this application. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0010] It is understood that the terms "each," "multiple," and "any" used in the embodiments of this application, etc., mean that "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the corresponding multiples. For example, multiple words include 10 words, and "each word" refers to each of the 10 words, while "any word" refers to any one of the 10 words.

[0011] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with the relevant laws, regulations and standards of the relevant countries and regions, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0012] Before implementing the embodiments of this application, the terms involved in the embodiments of this application will be explained first.

[0013] An ADC (Analog-to-Digital Converter) converts continuous signals (such as sound, temperature, and light intensity) into binary digital signals that can be processed by a digital system. For example, analog voltages collected by sensors are converted into digital values ​​by an ADC for computer analysis.

[0014] A DAC (Digital-to-Analog Converter), in contrast to an ADC, converts digital signals (such as binary code) into analog voltage or current signals to drive analog devices such as speakers and displays. For example, a digital audio file is converted into an analog signal by a DAC and output to headphones.

[0015] The successive approximation register (SAR) is the core control circuit in an analog-to-digital converter (ADC). Its function is to convert analog input signals into digital outputs using a successive approximation algorithm. The SAR works by employing a binary search algorithm, starting from the most significant bit (MSB) and gradually probing the input voltage. The conversion process begins by initializing the register to an intermediate value (e.g., setting the most significant bit to 1 after N bits are all zeros), generating the corresponding analog voltage, and comparing it with the input voltage. Based on the comparison result, the bit is determined to be either 1 or 0, and its value is retained. The process is then repeated to the next bit until the least significant bit (LSB) is reached. The entire process requires N clock cycles to complete the N-bit conversion, and the final digital result is stored in the register.

[0016] A buffer is a digital circuit device used to enhance signal driving capability or coordinate data transmission. Its core function is to ensure that signals are synchronized between high-speed and slow-speed components, reduce interference, and improve system stability.

[0017] The bit count of a temperature sensor typically refers to the resolution bit depth of its analog-to-digital converter (ADC), indicating the fineness with which the sensor can quantify temperature changes into a digital signal. A higher bit count means higher resolution and the ability to detect minute temperature changes.

[0018] Temperature drift refers to the phenomenon where changes in ambient temperature alter the parameters of semiconductor devices, leading to instability in the circuit's static operating point. This phenomenon is primarily caused by zero-point drift resulting from changes in the transistor's current amplification factor with temperature fluctuations. It manifests as a deviation of the output voltage from a fixed value when the input signal to the amplifier circuit is zero. In directly coupled amplifier circuits, the drift voltage propagates and amplifies interference signals at each stage, while in RC coupling circuits, the drift voltage is blocked from propagation by the capacitor.

[0019] Temperature drift (ppm / °C) of a voltage reference refers to the fraction of a millionth that the voltage deviates from its nominal voltage value for every 1°C change in temperature. For a reference voltage, its output voltage value will deviate from its nominal voltage value as temperature changes. Temperature drift (ppm / °C) is a quantification of this deviation, indicating how many parts per million the voltage changes for every 1°C change in temperature.

[0020] Current-mode architecture is a circuit design method that uses current signals as the core processing variable. Its basic principle is to utilize the superposition or transmission characteristics of current to achieve functions such as signal amplification, conversion, or reference generation. In practical applications, current-mode architecture is often used in bandgap reference circuits. By superimposing currents with positive and negative temperature coefficients according to specific weights, a reference current insensitive to changes in process technology, power supply voltage, and temperature is generated. For example, in the current-mode architecture of a bandgap reference, the temperature coefficient needs to be optimized through parameter scanning (such as adjusting resistor values ​​R2, R4, etc.). After first-order compensation, a curvature compensation branch may be introduced to further reduce higher-order temperature drift. However, it is important to note that improper current mirror replication ratio may introduce new temperature coefficient problems. The advantages of current-mode circuits include wide bandwidth, high slew rate, large dynamic range, and low power consumption, making them particularly suitable for high-speed or low-voltage scenarios. Typical circuits include current mirrors, transconductance amplifiers, and switching current circuits. These structures simplify MOS transistor circuit design and achieve accurate current transmission and processing.

[0021] Negative temperature coefficient (NTC) and positive temperature coefficient (PTC) are two different types of temperature-sensitive elements that play important roles in electronic devices and systems, typically used for temperature measurement, temperature control, and overheat protection. For a negative temperature coefficient, its resistance decreases as temperature rises and increases as temperature falls. This characteristic allows it to provide protection or trigger certain actions when the temperature increases. For a positive temperature coefficient (PTC), its resistance increases as temperature rises and decreases as temperature falls.

[0022] The temperature sensors currently used in the market have an 8-bit bit count and a measurement accuracy of ±1℃, which cannot meet the requirements of display chips for precise temperature control. This results in the system being unable to respond to minute temperature drifts in a timely manner, which in turn affects the uniformity of brightness and the accuracy of color, thus limiting its application in the field of high-end precision displays.

[0023] To address the issue of low measurement accuracy in existing temperature sensors, this application proposes the following improvements based on existing temperature sensors: Firstly, the effective number of bits in the register has been increased, thus enabling the measurement of temperatures with higher accuracy.

[0024] Secondly, compensation is performed on the higher-order terms of the reference voltage output by the bandgap reference circuit, which improves the PPM of the reference voltage and reduces the influence of temperature on the reference voltage.

[0025] Thirdly, by adjusting the resistance values ​​of the resistors (specifically the second and fourth resistors) in the subtractor circuit, the temperature detection voltage output by the subtractor is adjusted. This temperature detection voltage is positively correlated with the temperature. By adjusting this temperature detection voltage, the temperature curve is adjusted to ensure that the measured temperature is within the required range.

[0026] In addition, by adjusting the structure of the input terminal of the digital-to-analog converter (DAC), the dual-ended differential input of the DAC is changed to a single-ended input, which can achieve ideal measurement accuracy while saving the area of ​​the input terminal.

[0027] This application provides a temperature sensor, see [link to relevant documentation] Figure 1 The temperature sensor includes a temperature detection unit and an analog-to-digital converter (ADC). The temperature detection unit is connected to the ADC, which includes a successive approximation register (SAR). The SAR has N bits, each of which is a binary number 0 or 0. N is a positive integer greater than 8, such as 14 or 16.

[0028] The temperature detection unit generates a reference voltage and a temperature detection voltage, and outputs these two voltages to the analog-to-digital conversion unit. The reference voltage is a reference voltage provided by the temperature sensor, and this reference voltage is related to the inherent properties of the temperature sensor and is independent of the external temperature. In this embodiment, the reference voltage can be represented as V. REF The temperature detection voltage is positively correlated with the currently detected temperature. By measuring the voltage value of this temperature detection voltage, the detected temperature value can be calculated. In this embodiment, the temperature detection voltage can be expressed as V. TEMP .

[0029] The analog-to-digital conversion unit is used to adjust the reference voltage N times based on the temperature detection voltage. Based on the relationship between the adjusted reference voltage and the temperature detection voltage, it adjusts the values ​​of N bits of the SAR in descending order of the most significant bit to obtain and output the target value sequence. This target value sequence consists of N values ​​from the SAR in descending order of the most significant bit, forming a binary value sequence.

[0030] Furthermore, to facilitate the determination of the temperature measured by the temperature sensor, this embodiment of the application pre-stores the correspondence between decimal value ranges and temperatures. For example, a decimal value range of 1300~1315 corresponds to a temperature of 20.1℃, a decimal value range of 1316~1320 corresponds to a temperature of 20.2℃, and so on. When the temperature sensor outputs a target value sequence, a binary-to-decimal conversion method is used to convert the target value sequence into decimal values. Then, by querying the correspondence between the decimal value range and the temperature, the temperature represented by the target value sequence is determined.

[0031] The temperature sensor provided in this embodiment employs a high-bit SAR structure. Since the temperature detection voltage is positively correlated with the currently detected temperature, it can reflect the current ambient temperature. The number of times the reference voltage is adjusted is related to the number of bits in the SAR; the more bits in the SAR, the more times the reference voltage is adjusted. Each adjusted reference voltage approaches the temperature detection voltage. The more times the reference voltage is adjusted, the closer the adjusted reference voltage is to the temperature detection voltage, and the more accurate the temperature measurement by the temperature sensor.

[0032] In another embodiment of this application, see Figure 1The temperature detection unit of this temperature sensor includes a bandgap reference circuit, a subtractor, a first buffer, a second buffer, and a third buffer. The first output terminal of the bandgap reference circuit is connected to the input terminal of the first buffer, the second output terminal of the bandgap reference circuit is connected to the input terminal of the second buffer, and the third output terminal of the bandgap reference voltage is connected to the input terminal of the third buffer. The output terminal of the first buffer is connected to the first input terminal of the subtractor, and the output terminal of the second buffer is connected to the second input terminal of the subtractor. The first, second, and third buffers are composed of operational amplifiers configured in unity gain, used to buffer the output signal of the bandgap reference circuit.

[0033] The working process of the temperature detection unit includes: after acquiring the external temperature signal, the bandgap reference circuit generates a positive temperature coefficient voltage, a negative temperature coefficient voltage, and a reference voltage. The positive temperature coefficient voltage can be generated through the positive feedback loop of the bandgap reference circuit and can be expressed as V. PTAT The negative feedback coefficient voltage can be generated through the negative feedback loop of the bandgap reference circuit and can be expressed as V. CTAT After generating the positive temperature coefficient voltage, negative temperature coefficient voltage, and reference voltage, the bandgap reference circuit inputs the positive temperature coefficient voltage into the first buffer through the first output terminal, the negative temperature coefficient voltage into the second buffer through the second output terminal, and the reference voltage into the third buffer through the third output terminal. Upon receiving the positive temperature coefficient voltage, the first buffer buffers it to obtain a buffered positive temperature coefficient voltage, which is then input into the first input terminal of the subtractor. Similarly, upon receiving the negative temperature coefficient voltage, the second buffer buffers it to obtain a buffered negative temperature coefficient voltage, which is then input into the second input terminal of the subtractor. Finally, upon receiving the reference voltage, the third buffer buffers it to obtain the reference voltage. By using the first, second, and third buffers to buffer the voltage output by the bandgap reference circuit, the driving capability of the bandgap reference circuit's output voltage is enhanced.

[0034] Furthermore, after receiving the buffered positive temperature coefficient voltage and the buffered negative temperature coefficient voltage, the subtractor calculates the difference between the two to obtain the temperature detection voltage. Generally, the positive temperature coefficient voltage itself has good linearity and can be used as a temperature sensing signal. However, because the voltage variation range of the positive temperature coefficient voltage is very small, directly using it as the temperature detection voltage would waste a large portion of the temperature sensor's operating range. Therefore, to expand the operating range of the temperature sensor, this embodiment uses the difference between the buffered positive temperature coefficient voltage and the buffered negative temperature coefficient voltage to determine the temperature detection voltage.

[0035] In another embodiment of this application, see Figure 1 The analog-to-digital conversion unit includes a comparator, a digital-to-analog converter (DAC), and a logic control module. The SAR is located within the logic control module. Specifically, the output of the third buffer is connected to the first input of the DAC; the outputs of the subtractor and the DAC are connected to the first and second inputs of the comparator, respectively; the output of the comparator is connected to the input of the logic control module; the first output of the logic control module is connected to the second input of the DAC; and the second output of the logic control module is connected to external electronic components of the temperature sensor.

[0036] Furthermore, after obtaining the temperature detection voltage, the subtractor inputs this voltage into the comparator of the analog-to-digital converter (ADC) unit. This allows the ADC unit to determine the value of the N bits of the SAR based on the SAR control logic. The core task of the SAR control logic is to perform bit-by-bit guessing in the control register, from the most significant bit (MSB) to the least significant bit (LSB). During guessing, the adjusted reference voltage is not accumulated starting from 0, but rather the midpoint of the previous value is used for each guess, thus determining the N-bit value within N comparisons. To implement the SAR control logic, the successive approximation register (SAR) stores the value corresponding to the currently guessed voltage. The digital-to-analog converter (DAC) converts the value in the successive approximation register (SAR) into the guessed voltage and inputs it into the comparator. The comparator compares the temperature detection voltage with the guessed voltage to verify whether the guessed voltage is higher or lower than the temperature detection voltage.

[0037] The following example illustrates the working process of SAR control logic, using a reference voltage of 5V, an actual temperature detection voltage of 3.2V, and a successive approximation register (SAR) with 4 bits.

[0038] Step 1: Guess the highest point The logic control module sets the value in the most significant bit (MSB) of the successive approximation register (SAR) to 1, and the values ​​in the remaining bits to 0. At this time, the value sequence stored in the successive approximation register SAR is 1000. The digital-to-analog converter (DAC) converts 1000 into the corresponding analog voltage of 2.5V and outputs it. The comparator compares the temperature detection voltage of 3.2V with the DAC output voltage of 2.5V. It finds that the temperature detection voltage is greater than the DAC output voltage, indicating that the initial guessed voltage value is too small. Therefore, the value of 1 in the most significant bit is retained.

[0039] Step 2: Guess the second highest point The logic control module retains the most significant bit (MSB) of the successive approximation register (SAR) at 1, and sets the value of the second most significant bit to 1. At this point, the SAR register stores the value sequence 1100. The digital-to-analog converter (DAC) converts 1100 to the corresponding analog voltage 3.75V and outputs it. The comparator compares the temperature detection voltage 3.2V with the DAC output voltage 3.75V. Finding that the temperature detection voltage is less than the DAC output voltage, it indicates that the second guessed voltage value is too large. Therefore, it retains the most significant bit value of 1 and changes the value of the second most significant bit to 0. The SAR register now stores the value sequence 1000.

[0040] Step 3: Guess the second lowest position The logic control module retains the most significant bit (MSB) of the successive approximation register (SAR) as 1 and the second most significant bit as 0, and sets the value of the second least significant bit to 1. At this point, the SAR register stores the numerical sequence 1010. The digital-to-analog converter (DAC) converts 1010 into the corresponding analog voltage 3.125V and outputs it. The comparator compares the temperature detection voltage (3.2V) with the DAC output voltage (3.125V). Finding that the temperature detection voltage is greater than the DAC output voltage, it indicates that the third guessed voltage value is too small, and retains the value of 1 in the second least significant bit. Therefore, the SAR register stores the numerical sequence 1010.

[0041] Step 4: Guess the lowest digit The logic control module retains the most significant bit (MSB) of the successive approximation register (SAR) as 1, the second most significant bit as 0, and the second least significant bit as 1, and sets the value of the least significant bit to 1. At this point, the SAR register stores the numerical sequence 1011. The digital-to-analog converter (DAC) converts 1011 into the corresponding analog voltage 3.4375V and outputs it. The comparator compares the temperature detection voltage (3.2V) with the DAC output voltage (3.4375V). Finding that the temperature detection voltage is less than the DAC output voltage, it indicates that the fourth guess's voltage value is too large. Therefore, the least significant bit is changed from 1 to 0, and the SAR register stores the numerical sequence 1010.

[0042] After the above four comparisons, the SAR control logic finally determines that the numerical sequence stored in the SAR register is 1010, and then outputs this numerical sequence. In simple terms, the SAR control logic uses a binary search method, through repeated trial and error and comparisons, to determine the numerical sequence corresponding to the temperature detection voltage.

[0043] Based on SAR control logic, after receiving a reference voltage, the digital-to-analog converter adjusts the reference voltage N times to obtain a N-adjusted reference voltage, which is then input into a comparator. The comparator compares the temperature detection voltage with the N-adjusted reference voltage, obtaining N comparison results, which are then input into the logic control module. Based on the N comparison results, the logic control module adjusts the values ​​of N bits in the SAR in descending order of the most significant bit to obtain the target value sequence and output it.

[0044] Traditionally, bandgap reference circuits obtain a zero-temperature-coefficient voltage by linearly adding a voltage with a negative temperature coefficient and a voltage with a positive temperature coefficient. However, these voltages are not perfectly linear; their voltage-temperature curves exhibit curvature. Without addressing this curvature, the reference voltage will drift significantly under extreme high and low temperatures, affecting the accuracy of temperature measurements by the temperature sensor. To improve the measurement accuracy of the temperature sensor, this embodiment employs second-order compensation to compensate for the higher-order terms of the reference voltage output by the bandgap reference circuit. Specifically, the bandgap reference circuit can extract a positive compensation current (less than a preset value) from the positive feedback loop containing the positive temperature coefficient voltage and a negative compensation current (less than a preset value) from the negative feedback loop containing the negative temperature coefficient voltage. Then, based on these positive and negative compensation currents, the higher-order terms of the reference voltage are compensated. The positive and negative compensation currents can be extracted using high-impedance branches or mirror transistors. By employing high-impedance branches or mirror transistors, small currents can be extracted without interfering with the stability of the main loop. For the extracted positive and negative compensation currents, the nonlinear characteristics of MOS (Metal-Oxide-Semiconductor) transistors or series bipolar transistors can be used to compensate for higher-order terms of the reference voltage.

[0045] The compensation process utilizing the nonlinear characteristics of the MOSFET involves designing the MOSFET in the compensation circuit to operate in the subthreshold region. In the subthreshold region, the drain current... With gate-source voltage It exhibits an exponential relationship, while Temperature-dependent. As temperature changes, the current in the positive feedback loop increases and the current in the negative feedback loop decreases. This causes a change in the gate potential of the MOS transistor in the compensation branch, causing it to move from the saturation region to the linear region (or vice versa). This state switching generates a current component that is dependent on the square of the temperature. The voltage generated by this current component flowing through a specific resistor can compensate for the higher-order terms of the reference voltage.

[0046] The compensation process using series bipolar transistors involves connecting one or more PNP transistors in series at the output of the bandgap reference circuit. An auxiliary circuit controls the current flowing through these series PNP transistors, ensuring a smaller current at low temperatures and a larger current at high temperatures (or vice versa). By changing the bias current of multiple series-connected PNP transistors, their voltage, which has a negative temperature coefficient, can be altered. The temperature characteristics of this additional The voltage drop constitutes the second-order compensation term of the reference voltage.

[0047] The temperature sensor provided in this application embodiment draws a current less than a preset value from the positive and negative feedback loops of the bandgap reference circuit to cancel the higher-order terms related to temperature in the bandgap reference expression, so that the reference voltage has a relatively good PPM over the full temperature range. The adjustment range of the drawn current is 1uA~6uA.

[0048] In another embodiment of this application, see Figure 2 The subtractor circuit includes an operational amplifier, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The operational amplifier includes a non-inverting input INP, an inverting input INN, and an output OUT. The power supply pins VDDA and GMDA of the operational amplifier are connected to the positive and negative power supplies, respectively. The positive temperature coefficient voltage is input to the non-inverting input INP of the operational amplifier through the first resistor R1, and the negative temperature coefficient voltage is input to the inverting input INN through the third resistor R3. The second resistor R2 is connected between the non-inverting input INP and ground, forming positive feedback. The fourth resistor is connected between the inverting input INN and the output OUT of the operational amplifier, forming negative feedback.

[0049] The subtractor in this embodiment utilizes an operational amplifier, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4 to amplify the difference in input voltage. It can be applied to scenarios that require precise measurement of the difference between two signals, such as sensor signal processing and audio signal processing.

[0050] In actual manufacturing processes, the effects of resistance and PVT (process, voltage, temperature) can significantly impact the temperature-dependent curve amplified by the subtractor, rendering the curve unusable within the required temperature range. To address deviations in the temperature curve caused by process variations, this embodiment requires adjustment of the subtractor's temperature curve. Since the subtractor's temperature curve is a positive correlation between temperature and the temperature detection voltage output by the subtractor, adjustment can be achieved by regulating the temperature detection voltage output by the subtractor.

[0051] like Figure 2As shown, the first resistor R1 and the second resistor R2 are located in the positive feedback loop, and the current flowing through the first resistor R1 and the second resistor R2 is equal; similarly, the third resistor R3 and the fourth resistor R4 are located in the negative feedback loop, and the current flowing through the third resistor R3 and the fourth resistor R4 is equal. Based on the principle that the current is equal in both the positive and negative feedback loops, we can conclude that: As can be seen from the two formulas above, the resistance values ​​of the second and fourth resistors affect the input voltage value of the subtractor, which in turn affects the output temperature detection voltage value of the subtractor. Therefore, in this embodiment, the output temperature detection voltage value of the subtractor can be adjusted by regulating the resistance values ​​of the second and fourth resistors, thereby adjusting the temperature curve of the subtractor so that the curve within the required temperature range is usable.

[0052] For specific implementation details, please refer to [link / reference]. Figure 3 The second resistor can be divided into multiple resistor units. The resistance values ​​of these multiple resistor units can be the same or different; this embodiment does not impose specific limitations on this. For each resistor unit, a switch can be connected in parallel. By controlling the opening and closing of the switches connected in parallel to the multiple resistor units, the resistance value of the circuit connected to the subtractor is adjusted, thereby adjusting the voltage value of the temperature detection voltage output by the subtractor. The adjustable resistance value of the second resistor is in the range of 180 ohms to 1200 ohms; the specific resistance value to be adjusted can be determined based on simulation results.

[0053] For specific implementation details, please refer to [link / reference]. Figure 3 The fourth resistor can be divided into multiple resistor units. The resistance values ​​of these multiple resistor units can be the same or different; this embodiment does not impose specific limitations on this. For each resistor unit, a switch can be connected in parallel. By controlling the opening and closing of the switches connected in parallel to the multiple resistor units, the resistance value of the circuit connected to the subtractor by the fourth resistor can be adjusted, thereby adjusting the voltage value of the temperature detection voltage output by the subtractor. The adjustable resistance value of the fourth resistor is in the range of 180 ohms to 1200 ohms; the specific resistance value to be adjusted can be determined based on simulation results.

[0054] Of course, in addition to the above-mentioned method of adjusting the resistance value, you can also choose a resistor material with a smaller temperature coefficient, or add a temperature compensation element to the circuit to ensure the stability of the temperature control curve at different temperatures.

[0055] The analog-to-digital conversion unit in this application includes a SAR register. To implement the SAR control logic, the analog-to-digital conversion unit includes a SAR digital-to-analog converter (DAC). Traditional SAR DACs have differential inputs, with symmetrical capacitor arrays at the input. This results in a large capacitor array area at the input, increasing not only the chip area and manufacturing cost of the temperature sensor, but also the space occupied on the wafer, increasing the probability of wafer defects and reducing chip manufacturing yield. Furthermore, a large capacitor array introduces significant parasitic capacitance, severely limiting the high-frequency performance and accuracy of the circuit. A larger capacitor array also leads to higher power consumption. These problems affect the performance of the temperature sensor; therefore, to improve the performance of the temperature sensor, it is necessary to reduce the area of ​​the SAR DAC's input.

[0056] Therefore, this application embodiment improves the input terminal of the digital-to-analog converter by selecting any one of the original differential input terminals in the digital-to-analog converter as the input. By changing the dual-ended input to a single-ended input, the area of ​​the input terminal capacitor array is reduced by half.

[0057] Furthermore, in this embodiment, the capacitors included at the input of the original digital-to-analog converter are divided into two capacitor arrays. Each capacitor array includes multiple capacitors connected in parallel, and an equivalent capacitor is connected in series between two adjacent capacitor arrays. The capacitance value of the equivalent capacitor is equal to the total capacitance value of any capacitor array. When determining the input of the digital-to-analog converter, any capacitor array and equivalent capacitor can be selected as the input capacitors. By segmenting the capacitors included at the input, the area of ​​the capacitors is further reduced. Figure 5 The capacitor structure at the input of the digital-to-analog converter is shown; see [link / reference]. Figure 5 The original digital-to-analog converter (DAC) input terminal included 14 capacitors connected in parallel. These 14 capacitors were split into two capacitor arrays, each containing 7 capacitors connected in parallel. Each capacitor array and its series equivalent capacitor can form the input terminal of one DAC. The two capacitor arrays and their equivalent capacitors can form the input terminals of two DACs, thus allowing two temperature sensors to be deployed on the original chip, achieving high-precision temperature measurement.

[0058] This embodiment of the application reduces the area of ​​the capacitor array by half by changing the input of the digital-to-analog converter to a single-ended input. Furthermore, by segmenting the capacitor array at the input of the original digital-to-analog converter, the area of ​​the capacitor array is further reduced, significantly improving the performance of the temperature sensor.

[0059] The temperature sensor provided in this application embodiment can be applied to silicon-based OLED (Organic Light-Emitting Diode) and AMOLED (Active-matrix organic light-emitting diode) fields, and can measure the temperature of display chips in these fields.

[0060] The temperature sensor provided in this application adopts a higher-order SARADC structure and, with a high-precision bandgap, can provide a reference voltage with smaller temperature drift, achieving higher measurement accuracy and providing a more reliable temperature measurement for the display chip, thereby achieving better display effects.

[0061] All of the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this application, and will not be described in detail here.

[0062] This application provides an electronic device, the electronic device including... Figure 1 The temperature sensor shown.

[0063] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0064] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A temperature sensor, characterized in that, The temperature sensor includes a temperature detection unit and an analog-to-digital conversion unit. The temperature detection unit is connected to the analog-to-digital conversion unit. The analog-to-digital conversion unit includes a successive approximation register (SAR), wherein the SAR has N bits, and N is a positive integer greater than 8. The temperature detection unit is used to generate a reference voltage and a temperature detection voltage, and outputs the reference voltage and the temperature detection voltage to the analog-to-digital conversion unit. The temperature detection voltage is positively correlated with the currently detected temperature. The analog-to-digital conversion unit is used to adjust the reference voltage N times based on the temperature detection voltage, and based on the relationship between the reference voltage after N adjustments and the temperature detection voltage, adjust the values ​​of the N bits of the SAR in order from the high bit to the low bit to obtain and output the target value sequence, which is composed of the N values ​​of the SAR from the high bit to the low bit.

2. The temperature sensor according to claim 1, characterized in that, The temperature detection unit includes a bandgap reference circuit, a subtractor, a first buffer, a second buffer, and a third buffer; the first output terminal of the bandgap reference circuit is connected to the input terminal of the first buffer, the second output terminal of the bandgap reference circuit is connected to the input terminal of the second buffer, and the third output terminal of the bandgap reference voltage is connected to the input terminal of the third buffer; the output terminal of the first buffer is connected to the first input terminal of the subtractor, and the output terminal of the second buffer is connected to the second input terminal of the subtractor. The bandgap reference circuit is used to generate a positive temperature coefficient voltage, a negative temperature coefficient voltage, and a reference voltage, and inputs the positive temperature coefficient voltage, the negative temperature coefficient voltage, and the reference voltage to the first buffer, the second buffer, and the third buffer, respectively. The first buffer is used to buffer the positive temperature coefficient voltage to obtain a buffered positive temperature coefficient voltage, and the buffered positive temperature coefficient voltage is input into the subtractor; The second buffer is used to buffer the negative temperature coefficient voltage to obtain a buffered negative temperature coefficient voltage, and then input the buffered negative temperature coefficient voltage into the subtractor. The subtractor is used to calculate the difference between the buffered positive temperature coefficient voltage and the buffered negative temperature coefficient voltage to obtain the temperature detection voltage; The third buffer is used to buffer the reference voltage to obtain the reference voltage.

3. The temperature sensor according to claim 2, characterized in that, The analog-to-digital conversion unit includes a comparator, a digital-to-analog converter, and a logic control module. The SAR is located in the logic control module. The output of the third buffer is connected to the first input of the digital-to-analog converter. The output of the subtractor and the output of the digital-to-analog converter are respectively connected to the first and second inputs of the comparator. The output of the comparator is connected to the input of the logic control module. The first output of the logic control module is connected to the second input of the digital-to-analog converter. The second output of the logic control module is connected to an external electronic component of the temperature sensor. The subtractor is also used to input the temperature detection voltage into the comparator; The digital-to-analog converter is used to adjust the reference voltage N times to obtain the reference voltage after N adjustments, and input the reference voltage after N adjustments to the comparator; The comparator is used to compare the temperature detection voltage with the reference voltage after N adjustments to obtain N comparison results, and input the N comparison results into the logic control module; The logic control module is used to adjust the values ​​of the N bits of the SAR in order from the most significant bit to the least significant bit based on the N comparison results, so as to obtain the target value sequence and output it.

4. The temperature sensor according to claim 2, characterized in that, The bandgap reference circuit is also used to extract a positive compensation current less than a preset value from the positive feedback loop where the positive temperature coefficient voltage is located, and to extract a negative compensation current less than a preset value from the negative feedback loop where the negative temperature coefficient voltage is located, and to compensate the reference voltage based on the positive compensation current and the negative compensation current.

5. The temperature sensor according to claim 2, characterized in that, The subtractor circuit includes an operational amplifier, a first resistor, a second resistor, a third resistor, and a fourth resistor. The operational amplifier includes a non-inverting input terminal, an inverting input terminal, and an output terminal. The positive temperature coefficient voltage is input to the non-inverting input terminal of the operational amplifier through the first resistor, and the negative temperature coefficient voltage is input to the inverting input terminal of the operational amplifier through the third resistor; The second resistor is connected between the non-inverting input of the operational amplifier and ground, and the fourth resistor is connected between the inverting input and the output of the operational amplifier.

6. The temperature sensor according to claim 5, characterized in that, The second resistor includes multiple resistor units, each of which is connected in parallel with a switch. By controlling the opening and closing of the switches connected in parallel with the multiple resistor units, the resistance value of the circuit of the second resistor connected to the subtractor is adjusted, thereby adjusting the voltage value of the temperature detection voltage output by the subtractor.

7. The temperature sensor according to claim 5, characterized in that, The fourth resistor includes multiple resistor units, each with a switch connected in parallel. By controlling the opening and closing of the switches connected in parallel on the multiple resistor units, the resistance value of the circuit connected to the subtractor of the fourth resistor is adjusted, thereby adjusting the voltage value of the temperature detection voltage output by the subtractor.

8. The temperature sensor according to claim 3, characterized in that, The input terminal of the digital-to-analog converter can be any one of the original differential input terminals in the digital-to-analog converter.

9. The temperature sensor according to claim 8, characterized in that, The input terminal of the digital-to-analog converter includes a capacitor array and an equivalent capacitor. The equivalent capacitor is connected in series with the capacitor array. The capacitor array includes multiple capacitors connected in parallel. The total capacitance value of the capacitor array is the same as the capacitance value of the equivalent capacitor.

10. An electronic device, characterized in that, The electronic device includes the temperature sensor according to any one of claims 1 to 9.

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