CN106919101B - Tunable pulse signal generator for driving LED - Google Patents

Abstract

The present application relates to a tunable pulse signal generator for driving LEDs. The generator includes: a power supply module, a field programmable gate array, a programmable potentiometer, a DC-DC converter, and a level converter; the field programmable gate array is used to generate pulse signals and control instructions The programmable potentiometer is used to adjust the resistance value according to the control instruction; the DC-DC converter is used to convert the power supply voltage input by the power module, and adjust the voltage according to the resistance value of the programmable potentiometer output; the level shifter is used for level shifting the pulse signal according to the adjustable voltage output by the DC-DC converter. The tunable pulse signal generator for driving an LED of the present disclosure can realize a pulse signal generator with precisely adjustable parameters.

Description

Tunable Pulse Generator for Driving LEDs

technical field

The present invention generally relates to a pulse signal generator, in particular, to a tunable pulse signal generator for driving LEDs.

Background technique

Various photoelectric conversion devices such as photomultiplier tubes and silicon photodetectors can convert optical signals into electrical signals and at the same time realize multiplication and amplification of photoelectric signals. They are widely used in scientific research, industrial production, environmental monitoring and medical equipment. . Different applications have different requirements for the performance accuracy of such photoelectric conversion devices, so it is very important to effectively perform performance calibration. By performing performance calibration of different photoelectric conversion devices, suitable devices can be selected for professional testing. At present, the performance of photoelectric conversion devices such as photomultiplier tubes is calibrated by photoelectron spectroscopy, and the more classic one is the single photoelectron calibration method.

Whether the single photoelectron spectrum (SPE) can be tested is one of the most important evaluation indicators for photoelectric conversion devices. Through the single photoelectron spectrum, the gain, peak-to-valley ratio, energy resolution and other characteristics of the photomultiplier tube can be scaled. The Transit Time Spread of the photomultiplier tube is defined as the performance under the single photoelectron spectrum, so the single photoelectron spectrum can also qualitatively know whether the transit time spread of the photomultiplier tube can be obtained. At the same time, the relative quantum efficiency and the relative collection efficiency of the photomultiplier tube can also be scaled by the single photoelectron spectrum. Therefore, the test of single photoelectron spectrum is very important for photoelectric conversion devices, and it is particularly important to successfully generate a single photon light source that meets the test requirements.

For electronic devices to control the light-emitting properties of light-emitting diodes (LEDs), or lasers, it is possible to generate single-photon states. The commonly used instrument and equipment is a signal generator, which generates a pulse signal. By adjusting the trigger frequency, the periodic repetition frequency of the optical signal can be obtained, and then the test trigger signal can be given. Then, by adjusting the magnitude of the voltage signal loaded on the LED, and then adjusting the light intensity, duty cycle, etc., the output of a single photon is realized.

Common commercial pulse generators, such as Tektronix AFG3102 arbitrary function generator, RIGOO's DG5352 signal generator, although there are certain differences in bandwidth, can generate sine wave, square wave, pulse wave, sawtooth wave, triangle wave, Sin Arbitrary waveforms including (x)/x, exponential growth and decay, Gaussian, Lorentz, haversine, DC, noise, etc., are more expensive. To drive LEDs for single-photon detection, only one pulse waveform is required, and due to the limitation of the dynamic range of the detector itself, the frequency requirements of the signal are not high, and only small pulses with small size and low price are generated. A signal generator suffices.

Therefore, a new signal generator is required.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

The invention provides a tunable pulse signal generator for driving an LED, which can output a tunable pulse signal.

Other features and advantages of the present invention will become apparent from the following detailed description, or be learned in part by practice of the present disclosure.

According to an aspect of the present invention, a tunable pulse signal generator for driving LEDs includes: a power supply module, a field programmable gate array, a programmable potentiometer, a DC-DC converter, and a level converter The field programmable gate array is used to generate pulse signals and control instructions; the programmable potentiometer is used to adjust the resistance value according to the control instructions; the DC-DC converter is used to input the power supply voltage to the power module converting, and adjusting the voltage output according to the resistance value of the programmable potentiometer; the level shifter is used for level shifting the pulse signal according to the adjustable voltage output by the DC-DC converter.

According to an embodiment of the present invention, it further includes a main control CPU for parsing data and sending the data to the field programmable gate array.

According to an embodiment of the present invention, the data analyzed by the main control CPU includes level amplitude, duty cycle, period, voltage source feedback resistance resistance, high level time and low level time.

According to an embodiment of the present invention, an Ethernet controller is further included for receiving an instruction.

According to an embodiment of the present invention, a host computer is further included for issuing an instruction.

According to an embodiment of the present invention, the main control CPU interacts with the field programmable gate array through a UART asynchronous serial port interface.

According to an embodiment of the present invention, the field programmable gate array interacts with the programmable potentiometer through an SPI interface.

According to an embodiment of the present invention, the field programmable gate array parses the received data, and sends the parsed parameters into corresponding registers.

According to an embodiment of the present invention, a delay unit is further included for controlling the delay of the pulse signal.

According to an embodiment of the present invention, a configuration module is further included for managing configuration data.

According to an embodiment of the present invention, the programmable potentiometer has a center contact and an input terminal, and the DC-DC converter has a high-potential output terminal and a low-potential output terminal, which are respectively connected with the center contact and an input terminal. The input terminal is connected.

The tunable pulse signal generator for driving an LED of the present disclosure is based on a field programmable gate array, and realizes pulse output with adjustable duty cycle and period, and is composed of a level converter, a DC-DC converter and a programmable potentiometer. The high-precision output voltage source realizes the output amplitude transformation, and finally realizes the pulse signal generator with precisely adjustable parameters. Through the interaction between the main control CPU and the host computer, the output of the signal generator can be easily adjusted.

Description of drawings

The above and other objects, features and advantages of the present invention will become more apparent from the detailed description of example embodiments thereof with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the composition of a tunable pulse signal generator for driving an LED according to an exemplary embodiment of the present disclosure.

FIG. 2 is a schematic diagram of the composition of a level conversion circuit according to an exemplary embodiment of the present disclosure.

FIG. 3 is a schematic diagram of the composition of a tunable pulse signal generator for driving an LED according to another exemplary embodiment of the present disclosure.

FIG. 4 is a frame diagram of a host CPU embedded program according to an example embodiment of the present disclosure.

FIG. 5 is a flowchart of a host CPU embedded program according to an example embodiment of the present disclosure.

FIG. 6 is a comparison diagram of output waveforms of a signal generator and a RIGOO DG5352 signal source according to an example embodiment of the present disclosure.

7 is a graph showing the results of a single photoelectron spectrum test using a tunable pulse signal generator for driving an LED according to an example embodiment of the present disclosure.

Detailed ways

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments, however, can be embodied in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The drawings are merely schematic illustrations of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated descriptions will be omitted.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided in order to give a thorough understanding of the embodiments of the present invention. However, those skilled in the art will appreciate that the technical solutions of the present invention may be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be employed. In other instances, well-known structures, methods, devices, implementations, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the invention.

The present disclosure uses the signal of the pulse generator to drive the LED, and the time characteristics and amplitude characteristics of the pulse signal generator will have a relatively large influence on the light-emitting characteristics of the LED. For the present disclosure, the more important parameters of the pulse signal generator include: rise time, fall time, frequency, duty cycle, output level, and the like.

FIG. 1 schematically shows a schematic diagram of the composition of a tunable pulse signal generator for driving an LED according to an exemplary embodiment of the present invention.

As shown in Figure 1, the tunable pulse signal generator for driving LED includes: power supply module, field programmable gate array, programmable potentiometer, DC-DC converter, and level shifter. Field programmable gate arrays are used to generate pulse signals and control instructions. The programmable potentiometer is used to adjust the resistance value according to the control command. The DC-DC converter is used to convert the power supply voltage input by the power supply module, and adjust the voltage output according to the resistance value of the programmable potentiometer. The level shifter is used to level shift the pulse signal according to the adjustable voltage output by the DC-DC converter.

As the core component of the signal generator, the field programmable gate array can generate pulse signals with adjustable duty cycle and period, and at the same time generate control instructions to control the programmable potentiometer. The programmable potentiometer, as the load of the DC-DC converter, receives the control command of the field programmable gate array to adjust the resistance value, so that the DC-DC converter can produce an adjustable level output. The power supply end of the level converter receives the adjustable voltage output by the DC-DC converter, and performs level conversion on the pulse signal generated by the field programmable gate array. The level shifter outputs the converted pulse signal whose amplitude is controlled by the adjustable voltage output by the DC-DC converter. Therefore, the output end of the level shifter is used as the output end of the signal generator, and can output a pulse signal with adjustable duty cycle, period and amplitude.

FIG. 2 schematically shows a schematic composition diagram of a level conversion circuit according to an exemplary embodiment of the present invention.

As shown in Figure 2, the DC-DC converter is powered by a power module, and the programmable potentiometer is used as a load to be electrically connected to the DC-DC converter. Under the control of the field programmable gate array, the two parts of the programmable potentiometer, the programmable potentiometer 1 and the programmable potentiometer 2, change the resistance value. By changing the resistance value of the programmable potentiometer 2, the DC-DC converter can generate a adjusted level output. The DC-DC converter and the programmable potentiometer form a programmable controllable high-precision output voltage source, the output voltage of which is determined by the resistance of the programmable potentiometer 2 of the feedback resistor. The programmable potentiometer can use an n-bit programmable potentiometer, so the resolution of the output level is 2.4/2^n, but the present disclosure is not limited to this.

FIG. 3 is a schematic diagram of the composition of a tunable pulse signal generator for driving an LED according to another exemplary embodiment of the present disclosure.

As shown in Figure 3, the tunable pulse signal generator for driving LED includes: host computer, main control CPU, Ethernet controller, power supply module, field programmable gate array, configuration module, programmable potentiometer, DC-DC conversion , level shifter.

The host computer, such as a PC, can be used to provide a human-computer interaction interface, and the program can be compiled and modified. In this embodiment, a PC is used, and those skilled in the art can also imagine that other devices can also be used to achieve the above functions, such as tablet computers, etc. , the present disclosure is not limited thereto.

The Ethernet controller is used to connect the host computer and the main control CPU to realize data transmission between the host computer and the main control CPU. Other data transmission methods can also be used, such as connection through a USB interface, WIFI connection, Bluetooth transmission, etc. This is limited. The Ethernet controller, for example, can use TI's DP83848 Ethernet physical layer driver chip, which supports 100M/10M self-adaptation, and is connected to the main control CPU through the MII/RMII interface.

The main control CPU receives the data sent by the host computer through the Ethernet controller. For example, the STM32F107 chip of ST company can be used. The chip takes cortex-m3 as the core and has a maximum operating frequency of 72MHz. The MII/RMII physical layer interface is connected to the 100M Ethernet physical layer chip. The main control CPU parses the received data, converts the level amplitude, duty cycle, and period into corresponding parameters. The two parts of the programmable potentiometer have resistance values R1 and R2, high-level time T1, and low-level time T2. Among them, R1 is 2bytes data, R2 is 2bytes data, T1 is 4bytes data, T2 is 4bytes data, all data is 12bytes in total. Before sending data each time, the main control CPU will pull down the IO pin synchronously as the write data frame identifier. When the IO pin is low, it means that a data frame starts, and when the IO pin is high, it means the data Frame ends.

As the core component of the signal generator, the field programmable gate array can generate pulse signals with adjustable duty cycle and period, and at the same time generate control instructions to control the programmable potentiometer. The main control CPU interacts with the field programmable gate array through the UART asynchronous serial port interface. After receiving the data frame of the main control CPU, the field programmable gate array parses the data frame, and respectively transmits the R1, R2, T1, The value of T2 is sent to the corresponding register. At the same time, start the forwarding part of the logic, write R1 and R2 into the programmable potentiometer through the SPI interface, and write T1 and T2 into the internal registers of the field programmable gate array.

The DC-DC converter is used to convert the power supply voltage of the power module. The programmable potentiometer is electrically connected with the DC-DC converter as a load, and the values of R1 and R2 are changed under the control of the field programmable gate array. Programmable potentiometers are generally composed of digital control circuits, memory and RDAC circuits. The RDAC circuit is an important part of the digital potential. It is a special digital/analog conversion circuit. Different from the general digital/analog circuit, the converted analog quantity is not a voltage value but a resistance value. Different types of programmable The digital control circuit of the potentiometer has different structures, but the main function is to control the RDAC after processing the input control signal, and the non-volatile memory is used to store the control signal and the tap position of the potentiometer. The DC-DC converter and the programmable potentiometer form a programmable controllable high-precision output voltage source, the output voltage of which is determined by the resistance value of the feedback resistor R2. The calculation formula of the output terminal voltage is: 1.2*R1/(R1+R2). The output terminal has an output capacity of 200mA and can drive a level shifter. The programmable potentiometer is 10-bit programmable, so the resolution of the output level is 3.6/2^10, the resistance error is 1‰, the resistance value range is 0~20K, and the output voltage range that can be controlled is 1.2V~3.6V .

The level shifter is used to level shift the pulse signal output by the field programmable gate array. It is powered by a programmable high-precision voltage source composed of a DC-DC converter and a programmable potentiometer. The level shifter is based on DC-DC. The adjustable voltage output by the converter adjusts the level of the pulse signal. The level shifter acts as a converter at the output end, which can change the signal level without causing signal distortion. The maximum digital frequency supported by this level shifter is above 500M.

The configuration module is used to manage configuration data.

The tunable pulse signal generator for driving an LED of the present disclosure is based on a field programmable gate array, and realizes pulse output with adjustable duty cycle and period, and is composed of a level converter, a DC-DC converter and a programmable potentiometer. The high-precision output voltage source realizes the output amplitude transformation, and finally realizes the pulse signal generator with precisely adjustable parameters. Through the interaction between the main control CPU and the host computer, the output of the signal generator can be easily adjusted.

It should be clearly understood that this disclosure describes how to make and use specific examples and that the principles of this disclosure are not limited to any details of these examples. Rather, these principles can be applied to many other implementations based on the teachings of this disclosure.

FIG. 4 is a frame diagram of an embedded program of the main control CPU according to an example embodiment of the present disclosure.

As shown in Figure 4, the embedded program in the main control CPU mainly implements the TCP/IP protocol stack, receives the data sent by the upper computer through the TCP/IP protocol, and processes and forwards the data at the application layer. The embedded program code structure realizes the porting of the Ethernet chip driver and the application layer program under the framework of the rt-thread operating system, and realizes the data transmission of the application layer through the UART driver.

5 is a flowchart of a host CPU embedded program according to an example embodiment of the present disclosure.

As shown in Figure 5, after the main control CPU receives the data through the Ethernet controller, it first checks the integrity of the data packet. Then the data such as duty ratio and level are converted to the value of the corresponding register in the field programmable gate array. The values of the corresponding registers include: high-level time, low-level time, and programmable potentiometer resistance. The CPU writes the value of the corresponding register of the field programmable gate array through the UART asynchronous serial port interface to realize the control of the field programmable gate array.

Field programmable gate array logic mainly includes data packet reception, data packet distribution and so on. The field programmable gate array receives the data value transmitted by the main control CPU through the UART asynchronous serial port, checks its integrity, and then writes the corresponding register. The high-level time and low-level time registers are processed inside the field programmable gate array to adjust the phase of the output clock of the phase-locked loop inside the field programmable gate array, and the pulse signals generated according to different phases are combined with logic to form an output waveform. Among them, the programmable potentiometer resistance value register value is sent into the programmable potentiometer through the SPI interface, which is used to control the feedback terminal voltage of the high-precision output voltage source, and then control the output terminal level of the high-precision output voltage source. The value in the delay register is put into the counter to control the delay between the input and output signals. Thus, the configuration of the period, duty cycle and output level of the pulse signal is completed in the field programmable gate array.

FIG. 6 is a comparison diagram of output waveforms of a signal generator and a RIGOO DG5352 signal source according to an exemplary embodiment of the present disclosure.

As shown in Figure 6, RIGOO DG5352 is a signal source produced by RIGOO Company, the maximum output analog bandwidth is 350MHz, and the output sampling rate is 1GSPS. The test oscilloscope model is RIGOO DS6104 oscilloscope, the bandwidth of this oscilloscope is 1G, the sampling rate is 5Gsps, and the 1.5G analog bandwidth probe is used together. The comparison of output waveform characteristics can be seen from the test result comparison table (see Table 1).

Table 1. Comparison table of test results

DG5352 output Signal generator output of the present disclosure rising edge 3.800ns 2.500ns falling edge 3.000ns 1.400ns frequency 1Hz～350MHz adjustable 0.01Hz～300Mhz adjustable duty cycle adjustable adjustable signal level 0～10V adjustable 1.2～3.6V adjustable

FIG. 7 is a graph of the results of a single photoelectron spectrum test using a tunable pulse signal generator for driving an LED according to an example embodiment of the present disclosure.

As shown in FIG. 7 , in a photomultiplier tube single photoelectron spectrum test test, the test data of the RIGOODG5352 signal source and the test data of the signal generator of the present disclosure are compared (see Table 2), it can be seen that the signal generator of the present disclosure , which can fully meet the test requirements of single photoelectron spectroscopy.

Table 2 Comparison of test results of photomultiplier tube single photoelectron spectrum

light supply equipment high pressure frequency duty cycle Amplitude DG5352 signal source 1560V 1KHZ 0.001% 1872mv Signal generator of the present disclosure 1560V 1KHZ 0.001% 2664mv

Exemplary embodiments of the present disclosure have been specifically shown and described above. It should be understood that the invention is not limited to the details of construction, arrangements, or implementations described herein; on the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (11)

1. A tunable pulse signal generator for driving an LED to generate a pulse signal with precisely adjustable parameters for driving the LED to generate a single photon output, comprising: the system comprises a power module, a field programmable gate array, a programmable potentiometer, a DC-DC converter and a level converter;

the field programmable gate array is used for generating pulse signals and control instructions;

the programmable potentiometer is used for adjusting the resistance value according to the control instruction, wherein the programmable potentiometer is an n-bit programmable potentiometer, and n is greater than or equal to 2;

the DC-DC converter is used for converting the power supply voltage input by the power supply module and adjusting the voltage output according to the resistance value of the programmable potentiometer;

the level converter is used for carrying out level conversion on the pulse signal according to the adjustable voltage output by the DC-DC converter.

2. The tunable pulse signal generator for driving an LED of claim 1, further comprising a master CPU for parsing data and sending to said field programmable gate array.

3. The tunable pulse signal generator for driving an LED of claim 2, wherein the data parsed by the master CPU includes level amplitude, duty cycle, period, voltage source feedback resistor resistance, high level time, and low level time.

4. The tunable pulse signal generator for driving an LED of claim 3, further comprising an ethernet controller for receiving the command.

5. The tunable pulse signal generator for driving an LED of claim 4, further comprising an upper computer for issuing commands.

6. The tunable pulse signal generator for driving an LED of claim 2, wherein said master CPU interacts with said field programmable gate array through a UART asynchronous serial port interface.

7. The tunable pulse signal generator for driving an LED of claim 1, wherein said field programmable gate array interacts with said programmable potentiometer through an SPI interface.

8. The tunable pulse signal generator for driving an LED of claim 1, wherein the field programmable gate array parses the received data, and feeds the parsed parameters into corresponding registers.

9. The tunable pulse signal generator for driving an LED of claim 1, further comprising a delay unit for controlling a delay of the pulse signal.

10. The tunable pulse signal generator for driving an LED of claim 1, further comprising a configuration module for managing configuration data.

11. The tunable pulse signal generator for driving an LED according to any one of claims 1 to 10, wherein the programmable potentiometer has a center contact and an input, and the DC-DC converter has a high potential output and a low potential output connected to the center contact and the input, respectively.

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