Method and power supply for enabling SiPM bias voltage to have temperature self-adaptive function

Abstract

The invention belongs to the technical field of photoelectric detection, and particularly relates to a method for enabling SiPM bias voltage to have a temperature self-adaption function and a power supply, and the method comprises the following steps: 1, carrying out the voltage conversion of an input voltage through a multi-stage voltage boosting unit, and enabling an output voltage to reach the working voltage of SiPM; 2, the output voltage in the step 1 serves as input voltage through a linear voltage stabilizing unit, temperature compensation control is conducted on the output voltage, and SiPM bias voltage changing along with the temperature is output. The SiPM bias voltage source with the temperature self-adaption function is designed, the power supply adopts a multi-stage voltage boosting and stabilizing mode, the function that the output voltage changes along with the change of the environment temperature is achieved in cooperation with the temperature-sensitive resistor, and the SiPM bias voltage source has the advantages of being low in ripple wave, high in precision, large in output current and high in conversion efficiency.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detection technology, specifically relating to a method and power supply for enabling SiPM bias voltage to have temperature adaptive function. Background Technology

[0002] Silicon photomultipliers (SiPMs) are an emerging type of photodetector device that can be powered by low voltage and fabricated into large-area detector arrays. A SiPM consists of hundreds or thousands of self-quenching single-photon avalanche photodiodes (SAPDs), also known as pixels or microcells. The internal structure of a SiPM is as follows... Figure 1 As shown, when a photon is incident on a photodiode, an electron-hole pair is generated. Due to the electric field distribution of the PN junction inside the photodiode, the electrons and holes are accelerated and separated, forming a current. This current is called dark current, which is proportional to the energy of the photon and the intensity of the incident light.

[0003] When the energy of the incident photons reaches a certain level, the dark current increases rapidly. This is because the electron-hole pairs within the photodiode begin to exhibit a gain effect. The gain effect refers to the phenomenon where, when electron-hole pairs are accelerated to sufficiently high energies, they excite surrounding electron-hole pairs, creating an electron avalanche effect. This avalanche effect leads to a rapid increase in charge. The SiPM output signal is the superposition of signals from all micro-units, thus forming a considerable current pulse.

[0004] However, when the ambient temperature changes, the breakdown voltage (V) br The voltage (V) will change accordingly, thus affecting the overvoltage. ov The magnitude of the overvoltage (V) ov ) refers to the bias voltage (V bias ) and breakdown voltage (V br The difference in gain and photon detection efficiency (PDE) of SiPM ultimately leads to fluctuations. Therefore, when using SiPM in contexts requiring precise measurements, a temperature-adaptive bias power supply is necessary.

[0005] Domestic and international research institutions have studied temperature-adaptive power supply mechanisms, primarily employing two methods. The first method uses a temperature sensor to acquire the ambient temperature, transmits this information to a control chip, and then outputs a compensation voltage for control. This method typically requires a microcontroller, resulting in bulky additional circuitry. The second method utilizes the temperature-sensitive characteristic of a thermistor, changing its resistance based on temperature variations to directly control the output voltage amplitude, thus achieving temperature adaptation. This method results in smaller circuitry, flexible resistance settings, and the ability to meet diverse application needs. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention aims to provide a method and power supply that enables SiPM bias voltage to have temperature adaptive function. By dynamically adjusting the bias voltage, the influence of temperature changes on the key performance parameters of SiPM is offset, ensuring that SiPM operates stably over a wide temperature range and improving system reliability, accuracy, and energy resolution.

[0007] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0008] A method for enabling temperature-adaptive bias voltage in SiPM includes the following steps:

[0009] Step 1: The input voltage is converted by a multi-stage voltage boosting unit so that the output voltage reaches the operating voltage of the SiPM.

[0010] Step 2: Using the linear voltage regulator unit, the output voltage from Step 1 is used as the input voltage to perform temperature compensation control on the output voltage, resulting in a SiPM bias voltage that varies with temperature.

[0011] Furthermore, in step 1, the multi-stage voltage boosting unit includes multiple voltage boosting units, which sequentially perform voltage conversion to progressively increase the output voltage.

[0012] Furthermore, in step 1, the multi-stage voltage boosting unit performs voltage conversion on the input DC voltage.

[0013] Furthermore, in step 2, an adjustable resistor is connected in series in the linear voltage regulator unit to measure changes in ambient temperature.

[0014] Furthermore, in step 2, the adjustable resistor is a thermistor with a positive temperature coefficient.

[0015] A power supply that enables the SiPM bias voltage to have temperature adaptive function using the above method includes a multi-stage voltage conversion circuit and a linear voltage regulator circuit connected in sequence; the multi-stage voltage conversion circuit is used to convert the input voltage so that the output voltage reaches the SiPM operating voltage; the linear voltage regulator circuit is used to perform temperature compensation control on the output voltage and output a SiPM bias voltage that varies with temperature.

[0016] Furthermore, the multi-stage voltage conversion circuit includes a first-stage voltage conversion circuit and a second-stage voltage conversion circuit connected in sequence.

[0017] Furthermore, the first-stage voltage conversion circuit uses a boost power supply chip to increase the input voltage from +5V to the output voltage from +12V.

[0018] Furthermore, the second-stage voltage conversion circuit uses a boost power supply chip to increase the input voltage from +12V to the output voltage from +32V.

[0019] Furthermore, a thermistor is connected in series in the linear voltage regulator circuit to make the output SiPM bias voltage change with temperature.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. A SiPM bias voltage source with temperature adaptive function was designed. The power supply adopts a multi-stage boost + regulation mode and, together with a thermistor, realizes the function of output voltage changing with the ambient temperature. It has the advantages of low ripple, high accuracy, large output current and high conversion efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of multiple SAPDs arranged in parallel inside a SiPM.

[0023] Figure 2 A flowchart illustrating a method for enabling temperature-adaptive bias voltage in SiPM systems.

[0024] Figure 3 This is the circuit diagram for the first-stage voltage conversion circuit;

[0025] Figure 4 The circuit diagram for the second-stage voltage conversion circuit;

[0026] Figure 5 This is a circuit diagram of a linear voltage regulator circuit;

[0027] Figure 6 This is a schematic diagram of the output voltage ripple. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0030] The terms “comprising”, “including”, etc., as used herein indicate the presence of the steps, features, operations, or components, but do not preclude the addition of one or more other steps, features, operations, or components.

[0031] The breakdown voltage of SiPM increases with increasing temperature (approximately 0.1-0.3% / ℃), leading to changes in overvoltage and consequently affecting the gain of SiPM.

[0032] Dark current increases exponentially with increasing temperature (it doubles for every 8-10°C increase in temperature), leading to increased noise and decreased signal-to-noise ratio.

[0033] SiPMs are commonly used in medical imaging (requiring constant temperature control), high-energy physics experiments (such as the GECAM project), aerospace (with large temperature differences), and outdoor lidar. In these applications, it is necessary to eliminate the impact of temperature variations on the key performance parameters of SiPMs and ensure that they operate stably over a wide temperature range.

[0034] The power supply is equipped with temperature adaptive function, and the output voltage changes with temperature as the bias voltage of SiPM. By monitoring the temperature in real time and dynamically adjusting the bias voltage, a constant overvoltage can be maintained, which can ensure the gain stability of SiPM and suppress dark current and crosstalk (such as signal interference between adjacent SPAD cells).

[0035] In some embodiments, the present invention provides a method for enabling SiPM bias voltage to have temperature adaptive function, comprising the following steps:

[0036] Step 1: The input voltage is converted using a multi-stage voltage boosting unit to bring the output voltage up to the SiPM's operating voltage. The multi-stage voltage boosting unit includes multiple voltage boosting units, which sequentially perform voltage conversion to progressively increase the output voltage. The multi-stage voltage boosting unit converts the input DC voltage.

[0037] Step 2: Using the output voltage from Step 1 as the input voltage through the linear voltage regulator unit, the output voltage is temperature compensated and controlled to output a SiPM bias voltage that varies with temperature. The linear voltage regulator unit has an adjustable resistor in series to measure changes in ambient temperature. The adjustable resistor is a thermistor with a positive temperature coefficient.

[0038] In some embodiments, the present invention provides a power supply that enables the SiPM bias voltage to have a temperature adaptive function, comprising a multi-stage voltage conversion circuit and a linear voltage regulator circuit connected in sequence; the multi-stage voltage conversion circuit is used to convert the input voltage so that the output voltage reaches the SiPM operating voltage; the linear voltage regulator circuit is used to perform temperature compensation control on the output voltage and output a SiPM bias voltage that varies with temperature.

[0039] The multi-stage voltage conversion circuit includes a first-stage voltage conversion circuit and a second-stage voltage conversion circuit connected in sequence. The first-stage voltage conversion circuit boosts the input voltage of +5V to the output voltage of +12V using a boost power supply chip; the second-stage voltage conversion circuit boosts the input voltage of +12V to the output voltage of +32V using the same boost power supply chip. A linear regulator circuit is connected in series with a thermistor to make the output SiPM bias voltage change with temperature.

[0040] Example

[0041] A power supply that enables temperature-adaptive bias voltage in SiPM consists of two parts: a DC-DC converter and a linear regulator (LDO). First, an LT3436 boosts the input +5V to +12V; then, the +12V is input to an LT8336, which converts it to +32V; finally, an LM317A is used for linear regulation, with a thermistor connected in series in the linear regulator circuit, thereby enabling the output bias voltage to change with temperature.

[0042] The circuit diagram for the first-stage voltage conversion circuit is as follows: Figure 3 As shown. The first-stage boost converter raises the power supply from +5V to +12V using the LT3436 boost power supply chip. With an input voltage of 3V to 25V, its maximum output current can reach 3A. The B220A is a Schottky diode with a rated average forward current of 2A and a reverse voltage of 20V. A typical forward voltage at 2A is 0.5V. The B220A only conducts current during the off-time. Its peak reverse voltage equals the regulator's output voltage, and its average forward current during normal operation equals the output current.

[0043] The second-stage voltage conversion circuit is shown in the circuit diagram below. Figure 4 As shown. The second-stage boost further boosts the +12V to +32V. The LT8336, as a new type of boost power supply chip, can minimize EMI radiation while providing high efficiency at high switching frequencies. It has the advantages of high efficiency, low power consumption, and low noise. The output voltage can be regulated by changing the values ​​of R3 and R4.

[0044] Linear voltage regulator circuit, circuit diagram as follows Figure 5As shown. The LM317A is an adjustable three-terminal regulator from Texas Instruments (TI), capable of providing over 1.5A of current over an output range of 1.25V to 37V, with 1% output voltage accuracy. Compared to standard fixed regulators, the LM317A offers better line and load regulation. In the LM317A regulator module, the adjustable resistor RT is a KOA LP731JTTE102F3600, designed to measure ambient temperature changes. This is a positive temperature coefficient (PTC) thermistor, characterized by low error, high voltage withstand capability, and a wide temperature coefficient range, making it suitable for power supplies requiring temperature adaptation.

[0045] The circuit uses the low-noise, high-efficiency LT3436 and LT8336 chips to gradually boost the +5V to +32V. Finally, the LM317A LDO linear regulator chip, paired with an LP73 series PTC thermistor, provides temperature compensation to control the output voltage between +26V and +30V. Simulation software was used to test the power supply, demonstrating the output voltage changes caused by variations in the thermistor resistance at different temperatures. Overshoot voltage and output current were also measured. The simulation results met design requirements. Power supply ripple was also measured using an oscilloscope. Figure 6 As shown, the ripple factor RF = 0.04%.

[0046] Subsequently, the temperature stability of the power supply was tested in an adjustable temperature chamber. Within the test temperature range, the bias accuracy of the power supply was 0.18%, and the output voltage variation was consistent with the simulated test results. To further compare the performance of the temperature-adaptive power supply, a control experiment was designed, and the effect of using a power supply with and without temperature adaptation on the preamplifier count rate was measured. The results show that using a temperature-adaptive power supply can effectively stabilize the SiPM gain and significantly reduce the fluctuation of the count rate with temperature. It can be used for outdoor detection power supply of multi-channel SiPM detectors (containing 100-150 SiPMs).

[0047] A power supply with temperature adaptive (compensation) function dynamically adjusts the bias voltage by monitoring the temperature in real time to maintain a constant overvoltage and ensure stable SiPM gain. By reducing the bias voltage at high temperatures or optimizing the operating point, dark current and crosstalk (such as signal interference between adjacent SPAD cells) are suppressed, improving the low-light detection capability of the SiPM. Automatic bias voltage calibration is achieved by establishing a temperature-bias voltage function relationship (such as a linear model). Consistent SiPM performance is ensured across a wide temperature range of -30℃ to +60℃, avoiding performance drift caused by temperature fluctuations.

[0048] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. Thus, the invention also intends to include any such variations, uses, or adaptations that fall within the scope of the claims and their equivalents.

[0049] The above embodiments are merely illustrative examples of the present invention. The present invention may also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of protection of the present invention should be defined by the claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A method for enabling SiPM bias voltage to have temperature adaptive function, characterized in that, Includes the following steps: Step 1: The input voltage is converted by a multi-stage voltage boosting unit so that the output voltage reaches the operating voltage of the SiPM. Step 2: Using the linear voltage regulator unit, the output voltage from Step 1 is used as the input voltage to perform temperature compensation control on the output voltage, resulting in a SiPM bias voltage that varies with temperature.

2. The method for enabling SiPM bias voltage to have temperature adaptive function as described in claim 1, characterized in that: In step 1, the multi-stage voltage boosting unit includes multiple voltage boosting units, which sequentially perform voltage conversion to progressively increase the output voltage.

3. The method for enabling SiPM bias voltage to have temperature adaptive function as described in claim 2, characterized in that: In step 1, the multi-stage voltage boost unit performs voltage conversion on the input DC voltage.

4. The method for enabling SiPM bias voltage to have temperature adaptive function as described in claim 1, characterized in that: In step 2, an adjustable resistor is connected in series in the linear voltage regulator unit to measure changes in ambient temperature.

5. A method for enabling SiPM bias voltage to have temperature adaptive function as described in claim 4, characterized in that: In step 2, the adjustable resistor is a thermistor with a positive temperature coefficient.

6. A power supply employing the method described in any one of claims 1-5, enabling the SiPM bias voltage to have temperature adaptive function, characterized in that: It includes a multi-stage voltage conversion circuit and a linear voltage regulator circuit connected in sequence; the multi-stage voltage conversion circuit is used to convert the input voltage so that the output voltage reaches the working voltage of SiPM; the linear voltage regulator circuit is used to perform temperature compensation control on the output voltage and output a SiPM bias voltage that varies with temperature.

7. A power supply with temperature-adaptive bias voltage as described in claim 6, characterized in that: The multi-stage voltage conversion circuit includes a first-stage voltage conversion circuit and a second-stage voltage conversion circuit connected in sequence.

8. A power supply with temperature-adaptive function for SiPM bias voltage as described in claim 7, characterized in that: The first-stage voltage conversion circuit uses a boost power supply chip to increase the input voltage from +5V to the output voltage from +12V.

9. A power supply with temperature-adaptive function for SiPM bias voltage as described in claim 7, characterized in that: The second-stage voltage conversion circuit uses a boost power supply chip to increase the input voltage from +12V to the output voltage from +32V.

10. A power supply with temperature-adaptive function for SiPM bias voltage as described in claim 6, characterized in that: The linear voltage regulator circuit incorporates a thermistor to enable the output SiPM bias voltage to vary with temperature.

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