Variable gain photoelectric detector signal processing system

Abstract

The invention discloses a variable gain photoelectric detector signal processing system. The system comprises a current-voltage conversion circuit, a signal gain circuit and a voltage identification circuit. The current-voltage conversion circuit converts a current signal output by the photoelectric detector into a voltage signal; the voltage identification circuit receives the voltage signal and inputs the voltage signal to at least one voltage comparator in the voltage identification circuit to obtain output signals of all the voltage comparators, and the output signals are combined into a voltage interval indication signal; the signal gain circuit is used for receiving the voltage signal and the voltage interval indication signal, performing signal gain processing on the voltage signal based on a preset gain value corresponding to the voltage interval indication signal to obtain a signal gain circuit output signal, and sending the signal gain circuit output signal to the field programmable gate array device. According to the system, the gain speed of the output signal of the photoelectric detector can be increased, the input current receiving range of the system is widened, and the processing capacity of the system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic packaging, and in particular to a photoelectric detector signal processing system with variable gain. Background Art

[0002] A photodetector is a sensor that converts light signals into electrical signals. It can detect properties of light such as intensity, frequency, phase or polarization. Therefore, photodetectors are widely used in various fields of production activities.

[0003] In actual working scenarios, multiple photodetectors are often used to form a photodetector array for spot detection, and each photodetector receives a different light intensity. If a fixed gain value is used in the back-end signal processing circuit of the photodetector to gain the output signal of each photodetector, the output result of the subsequent operation processing will be saturated or the signal will be too small to be submerged by noise, which will seriously affect the use of the photodetector.

[0004] To address the above problems, a readout circuit with variable gain is currently used to reduce the gain value of the output signal of the photodetector whose output result is saturated, and to increase the gain value of the output signal of the photodetector whose output result signal-to-noise ratio is too low, so as to avoid the situation in which the output result of subsequent calculation processing becomes saturated or too small to be submerged by noise due to excessive or insufficient signal amplification during the output signal amplification process.

[0005] At present, the research on variable gain uses a field-programmable gate array (FPGA) to determine whether the gain of the signal needs to be changed. Specifically, the current signal output by the photodetector is first converted into a voltage signal after current-voltage conversion, and the voltage signal is subjected to analog-to-digital conversion processing; then, the voltage signal after analog-to-digital conversion is read by FPGA and compared with the reference voltage to determine whether the gain needs to be changed. If the voltage value of the voltage signal is higher than the reference voltage, the voltage signal needs to be processed with low gain. If the voltage value of the voltage signal is lower than the reference voltage, the voltage signal needs to be processed with high gain. This processing process requires re-sampling and processing the output signal of the photodetector. However, this method is limited by the sampling speed of analog-to-digital conversion and the speed of FPGA judgment. In order to select an analog-to-digital converter with a larger input voltage range, its sampling speed will be limited. At present, the sampling speed of analog-to-digital conversion in the photodetector array signal processing circuit is 5M (200ns), so the speed of gaining the output signal of the photodetector is low and cannot meet actual needs. Summary of the invention

[0006] In view of this, the present application provides a photodetector signal processing system with variable gain, the main purpose of which is to solve the technical problem of low speed of gaining the output signal of the photodetector.

[0007] According to a first aspect of the present invention, there is provided a variable gain photodetector signal processing system for gaining an output signal of a photodetector, the system comprising a current-to-voltage conversion circuit, a signal gain circuit, and a voltage identification circuit comprising at least one voltage comparator;

[0008] The current-to-voltage conversion circuit is used to receive the detector output current signal output by the photodetector and convert the detector output current signal into a voltage signal;

[0009] The voltage identification circuit is used to receive the voltage signal, and input the voltage signal into each of the voltage comparators to obtain the output signal of each of the voltage comparators, and combine all the output signals into a voltage interval indication signal.

[0010] The voltage comparator is used to compare the voltage signal with a reference voltage preset for the voltage comparator, and different voltage comparators correspond to different reference voltages;

[0011] The signal gain circuit is used to receive the voltage signal and the voltage interval indication signal, and perform signal gain processing on the voltage signal based on a preset gain value corresponding to the voltage interval indication signal to obtain a signal gain circuit output signal, and send the signal gain circuit output signal to an external field programmable logic gate array device.

[0012] Optionally, the signal gain circuit includes a negative input resistor, a multi-channel analog switch device, a first operational amplifier and a plurality of gain control circuits; the first end of the negative input resistor is connected to the output end of the current-voltage conversion circuit, the second end of the negative input resistor is connected to the negative input end of the first operational amplifier, the positive input end of the first operational amplifier is grounded, the output end of the first operational amplifier is connected to the field programmable logic gate array device, and is used to output the signal gain circuit output signal to the field programmable logic gate array device; the connection end of the input ends of the plurality of gain control circuits connected in parallel is connected to the negative input end of the first operational amplifier. The multi-way analog switch device comprises a plurality of signal input terminals and a signal output terminal, each of the signal input terminals is respectively connected to an output terminal of the gain control circuit, and the signal output terminal of the multi-way analog switch device is connected to the output terminal of the first operational amplifier, wherein each of the signal input terminals is connected to a different gain control circuit; the control terminal of the multi-way analog switch device is connected to the output terminal of the voltage identification circuit, and is used to receive the voltage interval indication signal, and determine the signal input terminal corresponding to the voltage interval indication signal as the target signal input terminal, and control the target signal input terminal and the signal output terminal to be in a conductive state.

[0013] Optionally, the gain control circuit includes a gain control resistor and a gain control capacitor; the first end of the gain control resistor is connected to the negative input end of the first operational amplifier as the input end of the gain control circuit, and the second end of the gain control resistor is connected to the signal input end of the multi-channel analog switch device as the output end of the gain control circuit; the first end of the gain control capacitor is connected to the first end of the gain control resistor, and the second end of the gain control capacitor is connected to the second end of the gain control resistor.

[0014] Optionally, the voltage identification circuit includes a voltage reversal subcircuit and at least one voltage comparator; the input end of the voltage reversal subcircuit is connected to the output end of the current-voltage conversion circuit, for receiving the voltage signal, and performing voltage reversal processing on the voltage signal to obtain the voltage signal after voltage reversal processing; the output end of the voltage reversal subcircuit is connected to the input end of each of the voltage comparators, for sending the voltage signal after voltage reversal processing to the input end of each of the voltage comparators; the output end of each of the voltage comparators is connected to the control end of the multi-channel analog switch device of the signal gain circuit, for combining the output signals of all the voltage comparators into the voltage interval indication signal, and sending the voltage interval indication signal to the multi-channel analog switch device.

[0015] Optionally, the current-to-voltage conversion circuit includes a second operational amplifier, a first filtering circuit, a second filtering circuit and a voltage value determination circuit; the negative input terminal of the second operational amplifier is connected to the output terminal of the photodetector, the positive input terminal of the second operational amplifier is grounded, the output terminal of the second operational amplifier is respectively connected to the input terminal of the voltage inversion sub-circuit and the first terminal of the negative input resistor, the first voltage access terminal of the second operational amplifier is connected to the first external power supply, the second voltage access terminal of the second operational amplifier is connected to the second external power supply, and the voltage polarity provided by the first external power supply is opposite to that of the second external power supply; the first terminal of the first filtering circuit is connected to the first external power supply for filtering the voltage output by the first external power supply, the second terminal of the first filtering circuit is grounded, the first terminal of the second filtering circuit is connected to the second external power supply for filtering the voltage output by the second external power supply, and the second terminal of the second filtering circuit is grounded; the voltage value determination circuit is connected in parallel between the negative input terminal of the second operational amplifier and the output terminal of the second operational amplifier, and is used to control the voltage value of the voltage signal.

[0016] Optionally, the voltage value determination circuit includes a first resistor and a feedback capacitor; the connection end after the first end of the first resistor is connected to the first end of the feedback capacitor is connected to the negative input terminal of the second operational amplifier, and the connection end after the second end of the first resistor is connected to the second end of the feedback capacitor is connected to the output terminal of the second operational amplifier.

[0017] Optionally, the first filtering circuit includes a first capacitor and a second capacitor; the connection end after the first end of the first capacitor and the first end of the second capacitor are connected is connected to the first external power supply, and the connection end after the second end of the first capacitor and the second end of the second capacitor are connected is grounded; the second filtering circuit includes a third capacitor and a fourth capacitor; the connection end after the first end of the third capacitor and the first end of the fourth capacitor are connected is connected to the second external power supply, and the connection end after the second end of the third capacitor and the second end of the fourth capacitor are connected is grounded.

[0018] Optionally, the voltage inversion sub-circuit includes a third operational amplifier, a third filtering circuit, a fourth filtering circuit, a second resistor and an amplification factor control circuit; the first end of the second resistor is connected to the output end of the current-voltage conversion circuit, and the second end of the second resistor is connected to the negative input end of the third operational amplifier; the positive input end of the third operational amplifier is grounded, the output end of the third operational amplifier is respectively connected to the input end of each of the voltage comparators, the first voltage access end of the third operational amplifier is connected to the third external power supply, the second voltage access end of the third operational amplifier is connected to the fourth external power supply, and the third external power supply is connected to the fourth external power supply. The voltages provided have opposite polarities; the first end of the third filtering circuit is connected to the third external power supply for filtering the voltage output by the third external power supply, and the second end of the third filtering circuit is grounded; the first end of the fourth filtering circuit is connected to the fourth external power supply for filtering the voltage output by the fourth external power supply, and the second end of the fourth filtering circuit is grounded; the amplification factor control circuit is connected in parallel between the negative input terminal of the third operational amplifier and the output terminal of the third operational amplifier, and is used to control the voltage value of the voltage signal after voltage inversion processing output by the voltage inversion sub-circuit to the input terminal of each of the voltage comparators.

[0019] Optionally, the amplification factor control circuit includes a third resistor and a fifth capacitor; the connection end after the first end of the third resistor is connected to the first end of the fifth capacitor is connected to the negative input terminal of the third operational amplifier, and the connection end after the second end of the third resistor is connected to the second end of the fifth capacitor is connected to the output terminal of the third operational amplifier.

[0020] Optionally, the third filtering circuit includes a sixth capacitor and a seventh capacitor; the connection end after the first end of the sixth capacitor and the first end of the seventh capacitor are connected is connected to the third external power supply, and the connection end after the second end of the sixth capacitor and the second end of the seventh capacitor are connected is grounded; the fourth filtering circuit includes an eighth capacitor and a ninth capacitor; the connection end after the first end of the eighth capacitor and the first end of the ninth capacitor are connected is connected to the fourth external power supply, and the connection end after the second end of the eighth capacitor and the second end of the ninth capacitor are connected is grounded.

[0021] The present invention provides a variable gain photodetector signal processing system, first, the detector output current signal output by the photodetector is converted into a voltage signal through a current-voltage conversion circuit, and the voltage signal is input into a voltage identification circuit. Further, the voltage identification circuit includes a plurality of voltage comparators, each of which is used to receive a voltage signal and determine the magnitude relationship between the voltage signal and a reference voltage set for the voltage comparator; here, the voltage comparator will output an output signal in the form of a high level signal or a low level signal according to the magnitude relationship between the voltage signal received and the reference voltage.

[0022] Further, each voltage comparator in the voltage identification circuit will output an output signal based on the received voltage signal, and then the output signals output by all the voltage comparators can be combined to obtain a voltage interval indication signal. Here, for the high voltage voltage signal and the low voltage voltage signal, the level of the signal contained in the voltage interval indication signal will be different, or the combination of the high level signal and the low level signal will be different. Further, after receiving the voltage interval indication signal, the signal gain circuit performs signal gain processing on the voltage signal based on the preset gain value corresponding to the voltage interval indication signal. Here, different preset gain values ​​can be preset for different voltage interval indication signals, and a high gain value can be preset for the voltage interval indication signal corresponding to the low voltage voltage signal, and a low gain value can be preset for the voltage interval indication signal corresponding to the high voltage voltage signal, so as to perform signal gain processing on voltage signals of different voltages based on the appropriate gain value. The technical solution of the present application determines the gain value of the voltage signal through the output signal of the voltage comparator, and can complete the response within a few nanoseconds, eliminating the process of analog-to-digital conversion and the process of FPGA judgment, reducing the response time for gain selection, and greatly improving the speed of gaining the output signal of the photodetector.

[0023] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 A schematic structural diagram of a photoelectric detector signal processing system with variable gain provided by an embodiment of the present invention is shown;

[0026] Figure 2 A schematic diagram showing a configuration of a voltage comparator in an exemplary voltage identification circuit provided by an embodiment of the present invention is shown;

[0027] Figure 3 A schematic diagram showing a configuration of a voltage comparator in another exemplary voltage identification circuit provided by an embodiment of the present invention is shown;

[0028] Figure 4a A schematic diagram of the structure of a signal gain circuit provided by an embodiment of the present invention is shown;

[0029] Figure 4b A schematic structural diagram of a gain control circuit provided by an embodiment of the present invention is shown;

[0030] Figure 5 A schematic structural diagram of an exemplary signal gain circuit provided by an embodiment of the present invention is shown;

[0031] Figure 6 A schematic diagram of the structure of a voltage identification circuit provided by an embodiment of the present invention is shown;

[0032] Figure 7 A schematic diagram of the structure of a current-to-voltage conversion circuit provided by an embodiment of the present invention is shown;

[0033] Figure 8 A schematic structural diagram of a voltage inversion sub-circuit provided in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0035] In one embodiment, Figure 1 As shown, a variable gain photodetector signal processing system is provided, and the system is used to gain the signal output by the photodetector in a light spot detection scenario as an example for explanation. It should be noted that other scenarios using photodetectors are also applicable to this embodiment.

[0036] Furthermore, the variable gain photodetector signal processing system includes a current-to-voltage conversion circuit, a signal gain circuit, and a voltage identification circuit including at least one voltage comparator (not shown in the figure). Specifically, the current-to-voltage conversion circuit is used to receive the detector output current signal output by the photodetector and convert the detector output current signal into a voltage signal. The detector output current signal is a signal output by the photodetector for detecting the light spot and used to characterize the light spot related parameters.

[0037] Furthermore, the current-to-voltage conversion circuit can receive the detector output current signal in the form of current, and perform current-to-voltage conversion (IV conversion) on it to obtain a voltage signal.

[0038] Furthermore, the voltage identification circuit is used to receive the voltage signal, and input the voltage signal into each of the voltage comparators to obtain an output signal of each of the voltage comparators, and combine all of the output signals into a voltage interval indication signal.

[0039] The voltage comparator is used to compare the voltage signal with a reference voltage preset for the voltage comparator, and different voltage comparators correspond to different reference voltages. Here, the reference voltage can be input to the non-inverting input terminal or the inverting input terminal of the voltage comparator to provide a reference voltage for the voltage comparator.

[0040] Specifically, in the actual working process, the voltage range in which the voltage signal is located can be determined to determine whether the voltage signal is a saturated voltage signal that exceeds the acceptance range of the current gain circuit, that is, a voltage signal with a high voltage value, or a voltage signal with a low signal-to-noise ratio that is lower than the acceptance range of the current gain circuit, that is, a voltage signal with a low voltage value; here, the number of voltage intervals can be set according to actual needs, such as setting a low voltage interval, a medium voltage interval and a high voltage interval, or only setting a high voltage interval and a low voltage interval. The specific setting method and setting number of voltage intervals can be determined according to actual conditions and are not limited here.

[0041] As an example, Figure 2As shown, if three voltage intervals need to be set, namely, a low voltage interval [0V to 0.2V], a medium voltage interval [0.2V to 2V], and a high voltage interval [above 2V], two voltage comparators can be set, namely, a first example voltage comparator Ua and a second example voltage comparator Ub. The first example voltage comparator Ua obtains a reference voltage from the first power supply Ea by connecting the non-inverting input terminal to the first power supply Ea. Here, the first power supply Ea outputs a voltage of 2V. The second example voltage comparator Ub obtains a reference voltage from the second power supply Eb by connecting the inverting input terminal to the second power supply Eb. Here, the second power supply Eb outputs a voltage of 0.2V. So far, through two voltage comparators, a low voltage interval [0V to 0.2V], a medium voltage interval [0.2V to 2V], and a high voltage interval [above 2V] can be divided; the voltage interval in which the voltage signal is located can be determined by the level of the output signal of each voltage comparator in the voltage interval indication signal. Here, the voltage identification circuit may also include a voltage inversion subcircuit, which is arranged between the current-voltage conversion circuit and each voltage comparator, and is used to reverse the voltage of the negative voltage signal output by the current-voltage conversion circuit to obtain a positive voltage signal, and send the positive voltage signal to each voltage comparator. In the actual working process, if the voltage signal is a low voltage of 0.1V, the first example voltage comparator Ua outputs a high-level output signal, and the second example voltage comparator Ub outputs a low-level output signal. At this time, the voltage interval indication signal is a combination of the high-level signal of the first example voltage comparator Ua and the low-level signal of the second example voltage comparator Ub, which can determine that the voltage signal is in a low voltage interval within [0V to 0.2V].

[0042] Further, if the voltage signal is a medium voltage of 0.3V, the first example voltage comparator Ua outputs a high-level output signal, and the second example voltage comparator Ub outputs a high-level output signal. At this time, the voltage interval indication signal is a combination of the high-level signal of the first example voltage comparator Ua and the high-level signal of the second example voltage comparator Ub, which can determine that the voltage signal is in the medium voltage interval within [0.2V to 2V].

[0043] Furthermore, if the voltage signal is a high voltage of 3V, the first example voltage comparator Ua outputs a low-level output signal, and the second example voltage comparator Ub outputs a high-level output signal. At this time, the voltage interval indication signal is a combination of the low-level signal of the first example voltage comparator Ua and the high-level signal of the second example voltage comparator Ub, which can determine that the voltage signal is in a high voltage interval within [above 2V].

[0044] Further, as an example, Figure 3As shown, if two voltage intervals need to be set, namely, a low voltage interval [0V to 2V] and a high voltage interval [above 2V], a voltage comparator, namely, a third example voltage comparator Uc, can be set in the voltage identification circuit. The third example voltage comparator Uc obtains a reference voltage from the third power supply Ec by connecting the in-phase input terminal to the third power supply Ec. Here, the third power supply Ec outputs a voltage of 2V. Thus, a low voltage interval [0V to 2V] and a high voltage interval [above 2V] can be divided by a voltage comparator. Here, the voltage identification circuit can also include a voltage inversion subcircuit, which is arranged between the current-voltage conversion circuit and the third example voltage comparator Uc, and is used to perform voltage inversion on the negative voltage signal output by the current-voltage conversion circuit to obtain a positive voltage signal, and send the positive voltage signal to the third example voltage comparator Uc.

[0045] In the actual working process, if the voltage signal is a low voltage of 0.1V, the third example voltage comparator Uc outputs a high-level output signal. At this time, the voltage interval indication signal is a high-level signal of the third example voltage comparator Uc, which can determine that the voltage signal is in a low voltage interval within [0V to 2V].

[0046] Furthermore, if the voltage signal is a voltage of 5V, the third example voltage comparator Uc outputs a low-level output signal. At this time, the voltage interval indication signal is the low-level output signal output by the third example voltage comparator Uc, which can determine that the voltage signal is in the high voltage interval within [above 2V].

[0047] It should be noted that, depending on actual conditions, the current-to-voltage conversion circuit can be connected to the non-inverting input terminal or the inverting input terminal of the voltage comparator, and the power supply that provides the reference voltage for the voltage comparator can be connected to the non-inverting input terminal or the inverting input terminal of the voltage comparator, and this embodiment does not limit this.

[0048] Further, such as Figure 1 As shown, the signal gain circuit is used to receive the voltage signal and the voltage interval indication signal, and perform signal gain processing on the voltage signal based on a preset gain value corresponding to the voltage interval indication signal to obtain a signal gain circuit output signal, and send the signal gain circuit output signal to an external field programmable gate array device (Field Programmable Gate Array, FPGA). Here, the signal gain circuit output signal can be used as a signal obtained by performing gain processing on the output signal of the photodetector.

[0049] Furthermore, the signal gain circuit can send the signal gain circuit output signal to a preset analog-to-digital converter in the system or an external analog-to-digital converter, so that the analog-to-digital converter performs analog-to-digital conversion on the signal gain circuit output signal in the form of an analog signal, obtains the signal gain circuit output signal in the form of a digital signal, and sends the signal gain circuit output signal in the form of a digital signal to the FPGA device. The FPGA device can be a control device that receives the signal gain circuit output signal and performs subsequent processing on the signal gain circuit output signal.

[0050] Specifically, after receiving the voltage interval indication signal, the signal gain circuit performs signal gain processing on the voltage signal based on the preset gain value corresponding to the voltage interval indication signal. Here, different preset gain values ​​can be preset for different voltage interval indication signals. For the voltage interval indication signal corresponding to the low voltage voltage signal, a high gain value can be preset, and for the voltage interval indication signal corresponding to the high voltage voltage signal, a low gain value can be preset, so as to perform signal gain processing on voltage signals of different voltages based on appropriate gain values. Figure 2 In the corresponding example, the voltage interval indication signal corresponding to the low voltage interval representing that the voltage signal is too low is the high level signal of the first example voltage comparator Ua and the low level signal of the second example voltage comparator Ub, the voltage interval indication signal corresponding to the medium voltage interval representing that the voltage signal is normal is the high level signal of the first example voltage comparator Ua and the high level signal of the second example voltage comparator Ub, and the voltage interval indication signal corresponding to the high voltage interval representing that the voltage signal is too high is the low level signal of the first example voltage comparator Ua and the high level signal of the second example voltage comparator Ub.

[0051] Here, a preset gain value of 4 may be preset for the voltage interval indication signal corresponding to the low voltage interval, a preset gain value of 2 may be preset for the voltage interval indication signal corresponding to the medium voltage interval, and a preset gain value of 1 may be preset for the voltage interval indication signal corresponding to the high voltage interval. For example, when the received voltage interval indication signal is a high level signal of the first example voltage comparator Ua and a low level signal of the second example voltage comparator Ub, the voltage signal may be processed with a high gain, and the preset gain value is 4 at this time, so as to obtain the output signal of the signal gain circuit.

[0052] Furthermore, when the received voltage interval indication signal is a high level signal of the first example voltage comparator Ua and a high level signal of the second example voltage comparator Ub, the voltage signal can be processed with medium gain, and the preset gain value is 2 to obtain the signal gain circuit output signal.

[0053] Furthermore, when the received voltage interval indication signal is a low level signal of the first example voltage comparator Ua and a high level signal of the second example voltage comparator Ub, the voltage signal can be processed with low gain, and the preset gain value is 1 to obtain the signal gain circuit output signal.

[0054] It should be noted that, in the actual working process, the setting quantity and setting value of the preset gain value corresponding to the voltage interval indication signal can be determined according to the actual situation, which is not limited here and is also applicable to this embodiment.

[0055] The present embodiment provides a photodetector signal processing system with variable gain. First, the detector output current signal output by the photodetector is converted into a voltage signal through a current-voltage conversion circuit, and the voltage signal is input into a voltage identification circuit. Further, the voltage identification circuit includes a plurality of voltage comparators, each of which is used to receive a voltage signal and determine the magnitude relationship between the voltage signal and a reference voltage set for the voltage comparator; here, the voltage comparator outputs an output signal in the form of a high-level signal or a low-level signal according to the magnitude relationship between the voltage signal received and the reference voltage. Further, each voltage comparator in the voltage identification circuit will output an output signal based on the received voltage signal, and then the output signals output by all the voltage comparators can be combined to obtain a voltage interval indication signal. Here, for a high voltage voltage signal and a low voltage voltage signal, the combination of the high-level signal and the low-level signal contained in the voltage interval indication signal will be different. Further, after receiving the voltage interval indication signal, the signal gain circuit performs signal gain processing on the voltage signal based on the preset gain value corresponding to the voltage interval indication signal. Here, different preset gain values ​​can be preset for different voltage interval indication signals, a high gain value can be preset for the voltage interval indication signal corresponding to the low voltage voltage signal, and a low gain value can be preset for the voltage interval indication signal corresponding to the high voltage voltage signal, so as to perform signal gain processing on the voltage signals of different voltages based on the appropriate gain value. The technical solution of the present application determines the gain value of the voltage signal through the output signal of the voltage comparator, and can complete the response within a few nanoseconds, eliminating the process of analog-to-digital conversion and the process of FPGA judgment, reducing the response time for gain selection, and greatly improving the speed of gaining the output signal of the photodetector.

[0056] In an optional embodiment, if Figure 4a As shown, the signal gain circuit includes a negative input resistor Rs, a multi-channel analog switch device, a first operational amplifier U1 and a plurality of gain control circuits. Here, the impedance of each gain control circuit is different.

[0057] Specifically, the first end of the negative input resistor Rs is connected to the output end of the current-voltage conversion circuit to receive a voltage signal, the second end of the negative input resistor Rs is connected to the negative input end of the first operational amplifier U1, the positive input end of the first operational amplifier U1 is grounded, and the output end of the first operational amplifier U1 is connected to a field programmable logic gate array device to output the signal gain circuit output signal to the field programmable logic gate array device. Here, an analog-to-digital converter can be set between the output end of the first operational amplifier U1 and the field programmable logic gate array device to perform analog-to-digital conversion on the signal gain circuit output signal. Further, the positive input end of the first operational amplifier U1 can be grounded through a fifth resistor (not shown in the figure) serving as a balancing resistor.

[0058] Further, the connection end after the input ends of the multiple gain control circuits are connected is connected to the negative input end of the first operational amplifier U1. Further, the multi-way analog switch device includes multiple signal input ends Sin and a signal output end Sout, each of the signal input ends Sin is respectively connected to an output end of the gain control circuit, and the signal output end Sout of the multi-way analog switch device is connected to the output end of the first operational amplifier U1, wherein the gain control circuit connected to each of the signal input ends Sin is different.

[0059] Further, the control end of the multi-channel analog switch device is connected to the output end of the voltage identification circuit, and is used to receive the voltage interval indication signal, and determine the signal input end Sin corresponding to the voltage interval indication signal as the target signal input end, and control the target signal input end and the signal output end Sout to be in a conductive state. Here, the corresponding signal input end Sin can be set in advance for different voltage interval indication signals, and when different voltage interval indication signals are received, the signal input end Sin corresponding to the voltage interval indication signal can be determined. Among them, a signal channel is formed between each signal input end Sin and the signal output end Sout, and each signal input end Sin corresponds to a signal channel. When the voltage interval indication signal indicates that a certain signal input end Sin is the target signal input end, the signal channel between the target signal input end and the signal output end Sout is conductive, and the signal channels between other signal input ends Sin and the signal output ends Sout are disconnected.

[0060] Here, the voltage range indication signal can be directly read by the multi-channel analog switch device, and the encoding form of the control signal output by the voltage comparator determines which signal input terminal Sin and signal output terminal Sout the multi-channel analog switch controls to be turned on, so as to connect the gain control circuit with different impedances between the negative input terminal of the first operational amplifier U1 and the output terminal of the first operational amplifier U1, thereby determining the value of the gain.

[0061] Further, such as Figure 4b As shown, the gain control circuit includes a gain control resistor and a gain control capacitor; specifically, the first end of the gain control resistor is connected to the negative input terminal of the first operational amplifier U1 as the input terminal of the gain control circuit, and the second end of the gain control resistor is connected to a signal input terminal Sin of the multi-channel analog switch device as the output terminal of the gain control circuit.

[0062] Furthermore, a first end of the gain control capacitor is connected to a first end of the gain control resistor, and a second end of the gain control capacitor is connected to a second end of the gain control resistor.

[0063] Here, the resistance value of each gain control resistor in the gain control circuit is different. Different gain control resistors can be connected in parallel between the negative input terminal and the output terminal of the first operational amplifier U1 to set an impedance between the negative input terminal and the output terminal of the first operational amplifier U1, so as to change the ratio of the impedance between the negative input terminal and the output terminal of the first operational amplifier U1 to the resistance of the negative input resistor Rs, thereby controlling the preset gain value when the voltage signal is gain-performed. Here, gain control resistors with different resistance values ​​can be pre-set in the gain control circuit to pre-set the impedance of the gain control circuit; further, the ratio of the impedance between the negative input terminal and the output terminal of the first operational amplifier U1 to the resistance of the negative input resistor Rs is the preset gain value.

[0064] Furthermore, in the actual working process, the preset gain value of the voltage signal can be controlled by connecting the gain control circuit with different resistors between the negative input terminal and the output terminal of the first operational amplifier U1. Figure 2 Take the corresponding example as an example, Figure 5 As shown, if the number of gain control circuits is 3, namely the first gain control circuit, the second gain control circuit and the third gain control circuit, the signal input end of the multi-way analog switch device connected to the first gain control circuit is the first signal input end Sin1, the signal input end of the multi-way analog switch device connected to the second gain control circuit is the second signal input end Sin2, and the signal input end of the multi-way analog switch device connected to the third gain control circuit is the third signal input end Sin3.

[0065] Furthermore, the signal input terminal preset for the voltage interval indication signal of the low voltage interval is the first signal input terminal Sin1. When the multi-channel analog switch device receives the voltage interval indication signal corresponding to the low voltage interval, the first signal input terminal Sin1 can be determined as the target signal input terminal, and the first signal input terminal Sin1 and the signal output terminal Sout are connected, and the second signal input terminal Sin2 and the third signal input terminal Sin3 and the signal output terminal Sout are disconnected, so as to connect the first gain control circuit between the negative input terminal and the output terminal of the first operational amplifier U1, so that the signal gain circuit determines the gain value based on the ratio of the impedance of the target gain control circuit to the resistance of the negative input resistor Rs, and performs gain processing on the voltage signal.

[0066] It should be noted that the signal input terminals preset for different voltage interval indication signals and the resistance value of the gain control resistor in each gain control circuit can be determined according to actual conditions, which is not limited here and is also applicable to this embodiment. The embodiment provided by the present application can connect a specific gain control circuit to the first operational amplifier based on the received voltage interval indication signal to realize that the signal gain circuit determines the gain coefficient based on the ratio of the impedance of the gain control circuit connected in parallel with the first operational amplifier to the resistance value of the negative input resistor, and gains the voltage signal, thereby improving the system's selection speed and processing speed for signal gain, and significantly improving the system's speed of gaining the output signal of the signal gain circuit of the photodetector.

[0067] In an optional embodiment, if Figure 6 As shown, the voltage identification circuit includes a voltage inversion subcircuit and at least one voltage comparator.

[0068] Specifically, the input end of the voltage inversion subcircuit is connected to the output end of the current-voltage conversion circuit, and is used to receive the voltage signal, and perform voltage inversion processing on the voltage signal to obtain a voltage signal after voltage inversion processing. In actual work, the voltage value of the voltage signal obtained by current-voltage conversion of the current signal output by the photodetector is usually a negative value, and it is necessary to perform voltage inversion on it so that the voltage comparator can better perform voltage comparison on it. As an example, if the voltage signal output by the current-voltage conversion circuit is -0.3V, it is necessary to perform voltage inversion on it to obtain a voltage signal of 0.3V.

[0069] Furthermore, the output end of the voltage reversal subcircuit is connected to the input end of each of the voltage comparators, so as to send the voltage signal after the voltage reversal processing to the input end of each of the voltage comparators. Here, based on the actual situation, the voltage comparator can be connected to the output end of the voltage reversal subcircuit through its non-inverting input end or inverting input end, which is not limited here.

[0070] Further, the output end of each of the voltage comparators is connected to the control end of the multi-channel analog switch device of the signal gain circuit, so as to use the output signals of all the voltage comparators as the voltage interval indication signal, and send the voltage interval indication signal to the multi-channel analog switch device. Here, if the number of voltage comparators in the voltage identification circuit is 2, the first voltage comparator outputs a high-level signal "1" and the second voltage comparator outputs a high-level signal "1", then the form of the voltage interval indication signal can be "11", if the first voltage comparator outputs a high-level signal "1" and the second voltage comparator outputs a low-level signal "0", then the form of the voltage interval indication signal can be "10"; further, the method of combining the output signals of other numbers of voltage comparators into a voltage interval indication signal and the form of the voltage interval indication signal can be determined according to actual conditions, which is not limited in this embodiment and is also applicable to this embodiment.

[0071] The embodiments provided in the present application can convert the voltage signal output by the current-to-voltage conversion circuit into a positive voltage signal, so as to facilitate the subsequent voltage comparator to process the voltage signal.

[0072] In an optional embodiment, if Figure 7 As shown, the current-to-voltage conversion circuit includes a second operational amplifier U2, a first filtering circuit, a second filtering circuit and a voltage value determination circuit.

[0073] Specifically, the negative input terminal of the second operational amplifier U2 is connected to the output terminal of the photodetector, the positive input terminal of the second operational amplifier U2 is grounded, the output terminal of the second operational amplifier U2 is respectively connected to the input terminal of the voltage reversal sub-circuit and the first end of the negative input resistor RS, the first voltage access terminal of the second operational amplifier U2 is connected to the first external power supply E1, and the second voltage access terminal of the second operational amplifier U2 is connected to the second external power supply E2, and the voltage polarities provided by the first external power supply E1 and the second external power supply E2 are opposite.

[0074] Furthermore, the first end of the first filter circuit is connected to the first external power supply E1 for filtering the voltage output by the first external power supply E1, the second end of the first filter circuit is grounded, the first end of the second filter circuit is connected to the second external power supply E2 for filtering the voltage output by the second external power supply E2, and the second end of the second filter circuit is grounded.

[0075] Further, the voltage value determination circuit is connected in parallel between the negative input terminal of the second operational amplifier U2 and the output terminal of the second operational amplifier U2, and is used to control the voltage value of the voltage signal output by the output terminal of the current-voltage conversion circuit. Here, the output terminal of the second operational amplifier U2 serves as the output terminal of the current-voltage conversion circuit. Further, resistors with different resistance values ​​can be added to the voltage value determination circuit to adjust the voltage of the voltage signal output by the current-voltage conversion circuit.

[0076] The embodiment provided in the present application can filter the working power supply of the second operational amplifier based on the first filtering circuit and the second filtering circuit, and can set the voltage level of the voltage signal output by the current-voltage conversion circuit through the voltage value determination circuit, thereby improving the signal quality of the voltage signal output by the current-voltage conversion circuit.

[0077] In an optional embodiment, if Figure 7 As shown, the voltage value determination circuit includes a first resistor R1 and a feedback capacitor Cf. Here, the first resistor R1 is used as a gain resistor.

[0078] Specifically, the connection end after the first end of the first resistor R1 is connected to the first end of the feedback capacitor Cf is connected to the negative input terminal of the second operational amplifier U2, and the connection end after the second end of the first resistor R1 is connected to the second end of the feedback capacitor Cf is connected to the output terminal of the second operational amplifier U2.

[0079] In the embodiment provided in the present application, before the system operates, a first resistor with a specific resistance value can be connected to a voltage value determination circuit to adjust the signal voltage of a voltage signal output by a current-to-voltage conversion circuit, thereby improving the operability of the system.

[0080] In an optional embodiment, if Figure 7 As shown, the first filtering circuit includes a first capacitor C1 and a second capacitor C2.

[0081] Specifically, a connection end where the first end of the first capacitor C1 and the first end of the second capacitor C2 are connected is connected to the first external power supply E1, and a connection end where the second end of the first capacitor C1 and the second end of the second capacitor C2 are connected is grounded.

[0082] Furthermore, the second filtering circuit includes a third capacitor C3 and a fourth capacitor C4.

[0083] Specifically, the connection end after the first end of the third capacitor C3 and the first end of the fourth capacitor C4 are connected is connected to the second external power supply E2, and the connection end after the second end of the third capacitor C3 and the second end of the fourth capacitor C4 are connected is grounded. The embodiment provided by the present application can filter the working power supply of the second operational amplifier based on the first filtering circuit and the second filtering circuit, thereby improving the power supply quality of the second operational amplifier.

[0084] In an optional embodiment, if Figure 8 As shown, the voltage inversion sub-circuit includes a third operational amplifier U3, a third filtering circuit, a fourth filtering circuit, a second resistor R2 and an amplification factor control circuit.

[0085] Specifically, a first end of the second resistor R2 is connected to the output end of the current-voltage conversion circuit, and a second end of the second resistor R2 is connected to the negative input end of the third operational amplifier U3.

[0086] Furthermore, the positive input terminal of the third operational amplifier U3 is grounded, the output terminal of the third operational amplifier U3 serves as the output terminal of the voltage inversion sub-circuit, and is respectively connected to the input terminal of each voltage comparator (not shown in the figure), the first voltage access terminal of the third operational amplifier U3 is connected to the third external power supply E3, the second voltage access terminal of the third operational amplifier U3 is connected to the fourth external power supply E4, and the voltage polarity provided by the third external power supply E3 and the fourth external power supply E4 is opposite.

[0087] Furthermore, the first end of the third filter circuit is connected to the third external power supply E3 for filtering the voltage output by the third external power supply E3, the second end of the third filter circuit is grounded, the first end of the fourth filter circuit is connected to the fourth external power supply E4 for filtering the voltage output by the fourth external power supply E4, and the second end of the fourth filter circuit is grounded.

[0088] Further, the amplification factor control circuit is connected in parallel between the negative input terminal of the third operational amplifier U3 and the output terminal of the third operational amplifier U3, and is used to control the voltage value of the voltage signal after voltage inversion processing output by the voltage inversion subcircuit to the input terminal of each voltage comparator. Here, the ratio between the impedance of the amplification factor control circuit and the resistance of the second resistor R2 can be adjusted. Here, the voltage of the voltage signal may not be amplified when the voltage is reversed, and thus the ratio between the impedance of the amplification factor control circuit and the second resistor R2 is 1.

[0089] The embodiment provided in the present application can filter the working power supply of the third operational amplifier based on the third filtering circuit and the fourth filtering circuit, and can set the amplification factor of the voltage signal through the amplification control circuit when the voltage signal is reversed, thereby improving the signal quality of the voltage signal output by the voltage reversal sub-circuit, and can determine the amplification factor of the voltage signal according to actual conditions, thereby improving the operability of the voltage reversal sub-circuit.

[0090] In an optional embodiment, if Figure 8 As shown, the amplification factor control circuit includes a third resistor R3 and a fifth capacitor C5.

[0091] Specifically, the connection end after the first end of the third resistor R3 is connected to the first end of the fifth capacitor C5 is connected to the negative input end of the third operational amplifier U3, and the connection end after the second end of the third resistor R3 is connected to the second end of the fifth capacitor C5 is connected to the output of the third operational amplifier U3. Here, before the system works, the third resistor R3 with different resistance values ​​can be connected to the amplification control circuit to adjust the resistance ratio of the third resistor R3 to the second resistor R2, thereby adjusting the amplification factor of the voltage signal, thereby improving the operability of the voltage reversal sub-circuit.

[0092] In an optional embodiment, if Figure 8 As shown, the third filtering circuit includes a sixth capacitor C6 and a seventh capacitor C7.

[0093] Specifically, a connection end where the first end of the sixth capacitor C6 and the first end of the seventh capacitor C7 are connected is connected to the third external power supply E3, and a connection end where the second end of the sixth capacitor C6 and the second end of the seventh capacitor C7 are connected is grounded.

[0094] Furthermore, the fourth filtering circuit includes an eighth capacitor C8 and a ninth capacitor C9.

[0095] Specifically, the connection end after the first end of the eighth capacitor C8 and the first end of the ninth capacitor C9 are connected is connected to the fourth external power supply E4, and the connection end after the second end of the eighth capacitor C8 and the second end of the ninth capacitor C9 are connected is grounded.

[0096] The embodiment provided in the present application can filter the working power supply of the third operational amplifier based on the third filtering circuit and the fourth filtering circuit, thereby improving the power supply quality of the third operational amplifier.

[0097] The present embodiment provides a variable gain photodetector signal processing system that can determine the gain value of a voltage signal through the output signal of a voltage comparator, and can complete the response within a few nanoseconds, eliminating the analog-to-digital conversion process and the FPGA judgment process, reducing the response time for gain selection, and greatly improving the speed of gaining the output signal of the photodetector.

[0098] The above serial numbers of this application are only for description and do not represent the advantages and disadvantages of the implementation scenarios. The above disclosure is only a few specific implementation scenarios of this application, but this application is not limited to them, and any changes that can be thought of by technicians in this field should fall within the scope of protection of this application.

Claims

1. A variable gain photodetector signal processing system, used to gain the signal output by the photodetector, characterized in that: The system includes a current-to-voltage conversion circuit, a signal gain circuit, and a voltage identification circuit including at least one voltage comparator; The current-to-voltage conversion circuit is used to receive the detector output current signal output by the photodetector and convert the detector output current signal into a voltage signal; The voltage identification circuit is used to receive the voltage signal, and input the voltage signal into each of the voltage comparators to obtain the output signal of each of the voltage comparators, and combine all the output signals into a voltage interval indication signal. The voltage comparator is used to compare the voltage signal with a reference voltage preset for the voltage comparator, and different voltage comparators correspond to different reference voltages; The signal gain circuit is used to receive the voltage signal and the voltage interval indication signal, and perform signal gain processing on the voltage signal based on a preset gain value corresponding to the voltage interval indication signal to obtain a signal gain circuit output signal, and send the signal gain circuit output signal to an external field programmable logic gate array device.

2. The system according to claim 1, characterized in that The signal gain circuit includes a negative input resistor, a multi-channel analog switch device, a first operational amplifier and a plurality of gain control circuits; A first end of the negative input resistor is connected to the output end of the current-voltage conversion circuit, a second end of the negative input resistor is connected to the negative input end of the first operational amplifier, a positive input end of the first operational amplifier is grounded, and an output end of the first operational amplifier is connected to the field programmable logic gate array device, for outputting the signal gain circuit output signal to the field programmable logic gate array device; A connection end of the input ends of the plurality of gain control circuits connected in parallel is connected to the negative input end of the first operational amplifier; The multi-channel analog switch device comprises a plurality of signal input terminals and a signal output terminal, each of the signal input terminals is respectively connected to an output terminal of the gain control circuit, and the signal output terminal of the multi-channel analog switch device is connected to the output terminal of the first operational amplifier, wherein the gain control circuit connected to each of the signal input terminals is different; The control end of the multi-channel analog switch device is connected to the output end of the voltage identification circuit, and is used to receive the voltage interval indication signal, determine the signal input end corresponding to the voltage interval indication signal as the target signal input end, and control the target signal input end and the signal output end to be in a conductive state.

3. The system according to claim 2, characterized in that The gain control circuit includes a gain control resistor and a gain control capacitor; The first end of the gain control resistor is connected to the negative input end of the first operational amplifier as the input end of the gain control circuit, and the second end of the gain control resistor is connected to the signal input end of one of the multi-channel analog switch devices as the output end of the gain control circuit; The first end of the gain control capacitor is connected to the first end of the gain control resistor, and the second end of the gain control capacitor is connected to the second end of the gain control resistor.

4. The system according to claim 2, characterized in that The voltage identification circuit includes a voltage inversion subcircuit and at least one of the voltage comparators; The input end of the voltage inversion subcircuit is connected to the output end of the current-voltage conversion circuit, and is used to receive the voltage signal and perform voltage inversion processing on the voltage signal to obtain a voltage signal after voltage inversion processing; The output end of the voltage inversion subcircuit is connected to the input end of each of the voltage comparators, and is used to send the voltage signal after the voltage inversion process to the input end of each of the voltage comparators; The output end of each voltage comparator is connected to the control end of the multi-channel analog switch device of the signal gain circuit, so as to combine the output signals of all the voltage comparators into the voltage interval indication signal and send the voltage interval indication signal to the multi-channel analog switch device.

5. The system according to claim 4, characterized in that The current-to-voltage conversion circuit includes a second operational amplifier, a first filtering circuit, a second filtering circuit, and a voltage value determination circuit; The negative input terminal of the second operational amplifier is connected to the output terminal of the photodetector, the positive input terminal of the second operational amplifier is grounded, the output terminal of the second operational amplifier is respectively connected to the input terminal of the voltage inversion sub-circuit and the first terminal of the negative input resistor, the first voltage access terminal of the second operational amplifier is connected to the first external power supply, the second voltage access terminal of the second operational amplifier is connected to the second external power supply, and the voltage polarity provided by the first external power supply is opposite to that provided by the second external power supply; A first end of the first filter circuit is connected to the first external power supply for filtering the voltage output by the first external power supply, a second end of the first filter circuit is grounded, a first end of the second filter circuit is connected to the second external power supply for filtering the voltage output by the second external power supply, and a second end of the second filter circuit is grounded; The voltage value determination circuit is connected in parallel between the negative input terminal of the second operational amplifier and the output terminal of the second operational amplifier, and is used to control the voltage value of the voltage signal.

6. The system according to claim 5, characterized in that The voltage value determination circuit includes a first resistor and a feedback capacitor; The connection end after the first end of the first resistor is connected to the first end of the feedback capacitor is connected to the negative input terminal of the second operational amplifier, and the connection end after the second end of the first resistor is connected to the second end of the feedback capacitor is connected to the output terminal of the second operational amplifier.

7. The system according to claim 5, characterized in that The first filtering circuit includes a first capacitor and a second capacitor; A connection end where the first end of the first capacitor and the first end of the second capacitor are connected is connected to the first external power supply, and a connection end where the second end of the first capacitor and the second end of the second capacitor are connected is grounded; The second filtering circuit includes a third capacitor and a fourth capacitor; The connection end where the first end of the third capacitor and the first end of the fourth capacitor are connected is connected to the second external power supply, and the connection end where the second end of the third capacitor and the second end of the fourth capacitor are connected is grounded.

8. The system according to claim 4, characterized in that The voltage inversion subcircuit includes a third operational amplifier, a third filtering circuit, a fourth filtering circuit, a second resistor and an amplification factor control circuit; A first end of the second resistor is connected to the output end of the current-voltage conversion circuit, and a second end of the second resistor is connected to the negative input end of the third operational amplifier; The positive input terminal of the third operational amplifier is grounded, the output terminal of the third operational amplifier is respectively connected to the input terminal of each of the voltage comparators, the first voltage access terminal of the third operational amplifier is connected to the third external power supply, the second voltage access terminal of the third operational amplifier is connected to the fourth external power supply, and the voltage polarity provided by the third external power supply is opposite to that provided by the fourth external power supply; The first end of the third filter circuit is connected to the third external power supply for filtering the voltage output by the third external power supply, the second end of the third filter circuit is grounded, the first end of the fourth filter circuit is connected to the fourth external power supply for filtering the voltage output by the fourth external power supply, and the second end of the fourth filter circuit is grounded; The amplification factor control circuit is connected in parallel between the negative input terminal of the third operational amplifier and the output terminal of the third operational amplifier, and is used to control the voltage value of the voltage signal after voltage inversion processing output by the voltage inversion subcircuit to the input terminal of each voltage comparator.

9. The system according to claim 8, characterized in that The amplification factor control circuit includes a third resistor and a fifth capacitor; The connection end after the first end of the third resistor is connected to the first end of the fifth capacitor is connected to the negative input terminal of the third operational amplifier, and the connection end after the second end of the third resistor is connected to the second end of the fifth capacitor is connected to the output terminal of the third operational amplifier.

10. The system according to claim 8, characterized in that The third filtering circuit includes a sixth capacitor and a seventh capacitor; The connection end of the first end of the sixth capacitor and the first end of the seventh capacitor is connected to the third external power supply, and the connection end of the second end of the sixth capacitor and the second end of the seventh capacitor is grounded; The fourth filtering circuit includes an eighth capacitor and a ninth capacitor; The connection end after the first end of the eighth capacitor and the first end of the ninth capacitor are connected is connected to the fourth external power supply, and the connection end after the second end of the eighth capacitor and the second end of the ninth capacitor are connected is grounded.

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