Single event effect simulation method for successive approximation analog-to-digital converter

Abstract

The invention discloses a single event effect simulation method of a successive approximation analog-to-digital converter (ADC), which comprises the following steps: by utilizing a method of combining TCAD and SPICE, obtaining electrical curve data of a device through TCAD analog simulation, extracting the electrical curve data as a library file, calling the library file by the SPICE, and carrying out circuit modeling, so that the simulation of the single event effect of the ADC device can be realized, and the single event effect of the ADC device can be obtained under different LET and different angles. According to the influence of the single event effect on ADC device output, the fault propagation rule of the single event effect is deeply revealed. The problems of limited resources, high economic cost, complex test method design and the like of an ADC device radiation experiment accelerator are solved, and technical support is provided for carrying out anti-radiation evaluation and reinforcement design of the analog-to-digital converter.

Description

Technical Field

[0001] The invention relates to a single particle effect simulation method of a successive approximation analog-to-digital converter, belonging to the technical field of ADC single particle effect simulation. Background Art

[0002] Analog-to-digital converters (ADCs) are crucial in spacecraft, as they are responsible for collecting, feeding back, and adjusting the attitude and position information of spacecraft. However, in the space environment, ADC devices are susceptible to radiation. When high-energy charged particles are injected into the ADC, the generated ionized charges are collected by the internal electric field of the device, which may trigger single-particle effects of the ADC, mainly including single-particle transients (SETs) and single-particle upsets (SEUs).

[0003] Single-event transients occur when high-energy particles (e.g., protons, alpha particles, heavy ions, etc.) strike semiconductor materials and interact with the atoms in the material. These particles have enough energy to excite electron and hole pairs in the material, known as electron-hole pairs (EHPs). This excitation process forms a localized cloud of high-energy electrons in the semiconductor material. In the semiconductor material, the excited electrons and holes move under the action of the electric field. This movement produces a localized charge accumulation effect, which forms a transient current pulse. The intensity and duration of the current pulse depend on the energy of the particle, the impact location, and the characteristics of the semiconductor material. This transient current pulse can affect the voltage or current in the integrated circuit. Specifically, the current pulse can cause voltage changes at certain nodes in the circuit, which may change the logic state of the circuit.

[0004] Single event upset refers to the impact of high-energy particles on semiconductor materials, causing the state of the storage unit to change, thus causing data errors. Take NASA's "High Energy Observatory" project as an example. The mission of this project is to detect high-energy particles and conduct scientific observations. Researchers have found that the ADC in the spacecraft will change the value in the data register due to the SEU effect. This problem is particularly serious during the data acquisition process and may lead to misleading scientific data or system failures.

[0005] Single event transients are mainly generated in the analog circuit part of the ADC, such as the analog comparator, and can cause small fluctuations in the digital output. Single event upsets are mainly generated in the digital circuit part of the ADC, such as the output latch, and can cause large-scale offsets or misalignments in the digital output.

[0006] Research on single-particle effects of ADCs mainly focuses on the mechanisms, effects and protection strategies of SET and SEU. For example, some space agencies conduct detailed radiation testing and modeling of ADCs on spacecraft to study the specific effects of particles on ADC performance and propose targeted design improvement measures. Many research institutions and universities use advanced simulation tools to model the radiation response of ADCs, such as using TCAD (computer-aided design) software to accurately simulate the radiation response of semiconductor materials and circuits. Research institutions and universities have conducted a series of basic research and practical tests on single-particle effects, exploring the impact of radiation on ADC performance. However, for ADC devices with different structures, the degree of impact of single-particle effects on their performance varies greatly, making the cost of conducting irradiation experimental research high. Theoretical simulation research on ADC devices has the advantages of short time consumption, high accuracy and low economic cost, and is used as an important method to study single-particle effects of ADC devices. However, the current simulation of ADC devices is mainly based on the design of performance indicators of ADC devices, and there is a lack of a simulation method for studying single-particle effects of ADC devices. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of the prior art, provide a method for simulating the single particle effect of a successive approximation analog-to-digital converter, use a method combining TCAD and SPICE, extract the electrical curve data of the device obtained by TCAD simulation into a library file, SPICE calls the library file and performs circuit modeling, and can realize the simulation of the single particle effect of the ADC device, and can obtain the influence of the single particle effect on the output of the ADC device under different LET and different angles, and deeply reveal the fault propagation law of the single particle effect. It solves the problems of limited resources, high economic cost, and complex test method design of ADC device radiation experiment accelerator, and provides technical support for the evaluation and reinforcement design of analog-to-digital converter radiation resistance.

[0008] Preferably, the present invention provides a method for simulating a single event effect of a successive approximation analog-to-digital converter, comprising: Based on the process parameters in the device product manual, three-dimensional modeling of the device in the ADC device is performed to generate the device structure; Conduct electrical modeling of the device structure, optimize the parameters of the device structure, and obtain electrical curves; Extract the parameter data of the optimized device structure as a library file; By performing single-particle effect simulation on the device structure, we can obtain single-particle transient current curves at different linear energy transfer values ​​and different angles.

[0009] Prioritize, conduct circuit modeling on several modules of the overall circuit of the ADC device, and compile and obtain a netlist file based on the library file; The obtained single-particle transient current curve data is fitted with a double exponential model, and the current source is injected into each node of the overall circuit of the ADC device. The output voltage changes before and after the injection of each node are compared to determine the most sensitive node.

[0010] Prioritizes that single-particle transient currents with different linear energy transfer values ​​and angles are injected into the most sensitive node in the overall circuit of the ADC device to obtain the linear energy transfer threshold at which the single-particle effect occurs in the overall circuit of the ADC device, as well as the effects of different linear energy transfer values ​​and different angles on the single-particle effect of the ADC device.

[0011] Preferably, the plurality of modules include a DAC module, a comparator module and a successive approximation logic module.

[0012] Preferably, the same single-particle transient current is injected into all the most sensitive nodes on the switch branches of the DAC module in the form of a current source to obtain the single-particle effect variation law of all the most sensitive node devices on the switch branches of the DAC module.

[0013] Preferably, the parameters of the device structure include substrate, drift region, source region size and concentration.

[0014] Preferably, the parameters of the incident particle in the single-particle effect simulation include the LET value, incident position, exit position, track radius, characteristic time parameter and peak time of the incident particle.

[0015] Preferably, the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the methods described in the first aspect when executing the program.

[0016] Preferably, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods described in the first aspect.

[0017] The beneficial effects achieved by the present invention are: The present invention innovatively proposes a method for simulating single particle effects of ADC based on TCAD and SPICE. By combining TCAD and SPICE, the electrical curve data of the device is extracted into a library file through TCAD simulation. SPICE calls the library file and performs circuit modeling, which can realize the simulation of single particle effects of ADC devices. The influence of single particle effects on the output of ADC devices under different LETs and different angles can be obtained, and the fault propagation law of single particle effects can be deeply revealed. It solves the problems of limited resources, high economic cost, and complex test method design of ADC device radiation experiment accelerators, and provides technical support for the evaluation and reinforcement design of analog-to-digital converters. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] Figure 1 is a flow chart of some embodiments of the present application; Figure 2 This is a structural diagram of the MOS tube, a core unit inside the ADC device in some embodiments of the present application; Figure 3 is a transfer characteristic curve diagram of a MOS tube in some embodiments of the present application; Figure 4 is an output characteristic curve diagram of a MOS tube in some embodiments of the present application; Figure 5 is a schematic diagram of the heavy ion incident position in some embodiments of the present application; Figure 6 is a graph of single particle transient current at different LET values ​​in some embodiments of the present application; Figure 7 is a graph of single-particle transient current at different angles in some embodiments of the present application; Figure 8 is a basic topological structure diagram of a SAR ADC in some embodiments of the present application; Fig. 9 is a circuit structure diagram of a DAC module in some embodiments of the present application; Fig.10 is a diagram of a comparator circuit structure in some embodiments of the present application; Fig.11 is a diagram of a successive approximation logic circuit structure in some embodiments of the present application; Fig.12 is an output waveform diagram of a DAC in some embodiments of the present application; Fig.13 is a comparator output waveform diagram in some embodiments of the present application; Fig.14 is a successive approximation logic output waveform diagram in some embodiments of the present application; Fig.15 is a waveform diagram of ADC output signal in some embodiments of the present application; Fig.16 is a schematic diagram of the change in analog output voltage of the ADC under different LETs in some embodiments of the present application; Fig.17 is a schematic diagram of changes in analog output voltage of an ADC at different incident angles in some embodiments of the present application; Fig.18 This is a schematic diagram of the change in ADC output voltage when a DAC is injected with a fault in some embodiments of the present application. DETAILED DESCRIPTION

[0020] See also Figure 1 The present application discloses a method for simulating single particle effects of a successive approximation ADC based on TCAD and SPICE, which is characterized by comprising: (1) Step 1: Based on the process parameters in the device product manual, the core unit MOS tube in the ADC device is 3D modeled using the mainstream semiconductor process and device simulation tool TCAD. The device structure is first generated, and then meshing is performed to generate a meshed device structure. (2) Step 2: Based on step 1, use TCAD to perform electrical modeling on the device structure, optimize the parameters of the device structure such as substrate, drift region, source region size and concentration, so that the obtained electrical curve is consistent with the device product manual, and extract the optimized parameter data into a library file format; (3) Step 3: Add a single particle effect statement based on step 2; define the LET value of the incident particle (Linear Energy Transfer, which physically means the energy deposited per unit density and unit length, and can also be expressed as the number of charges deposited per unit trajectory length, in MeV cm 2 / mg), incident position, exit position, track radius, characteristic time parameters and peak time parameters, and perform single particle effect simulation on the device structure to obtain single particle transient current curves at different linear energy transfer values ​​and different angles; (5) Step 4: Divide the overall circuit of the ADC device into three modules: DAC module, comparator module, and successive approximation logic module. Use SPICE software to model the circuits of each module and write a netlist file, which requires calling the library file extracted in step 2 to finally complete the overall modeling of the ADC device. (6) Step 5: Fit the single-particle transient current curve data obtained in step 3 with a double exponential model, inject it into each node of the circuit in the form of a current source, compare the output voltage changes before and after the injection of each node, and find the most sensitive node of the overall circuit of the ADC device; (7) Step 6: For the most sensitive node in the overall circuit of the ADC device, inject single-particle transient currents with different linear energy transfer values ​​and different angles to obtain the linear energy transfer threshold at which the single-particle effect occurs in the overall circuit of the ADC device and the influence of different linear energy transfer values ​​and different angles on the single-particle effect of the ADC device; (8) Step 7: For the different most sensitive nodes on the DAC module switch branch, the same single-particle transient current is injected into each node in the form of a current source, and the variation law of the single-particle effect of the different most sensitive node devices is obtained.

[0021] In an embodiment of the present application, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the above methods when executing the program.

[0022] In an embodiment of the present application, the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0023] like Figure 1 As shown, a method for simulating single particle effects of a successive approximation ADC based on TCAD and SPICE includes the following steps: Step 1: Figure 2 As shown in the figure, it is a two-dimensional cross-sectional view of the core unit MOS tube structure inside the ADC device. According to the process parameters in the device product manual, the core unit MOS tube in the ADC device is 3D modeled using TCAD. First, the device structure is generated. The lateral width of the device is 0.1μm, the longitudinal width is 0.4μm, and the height is 0.6μm. Si substrate material is selected, and the thickness, doping material, and doping concentration of each region such as the substrate, buffer layer, channel, and barrier layer are set. Each region is meshed to generate a gridded device structure.

[0024] Step 2: Use TCAD to perform electrical modeling on the device, optimize the device's substrate, drift region, source region size and concentration and other parameters, so that the obtained electrical curve is consistent with the device product manual. The transfer and output characteristic curves of the MOS device are as follows: Figure 3 , Figure 4 As shown, the transfer characteristic curve is obtained by adding a gate voltage of 1V and a drain voltage of 0.05V; the output characteristic curve is obtained by adding a drain voltage of 1V and gate voltages of 0.5V, 1V, and 1.5V. The optimized model parameter data is extracted in the form of a library file for subsequent circuit simulation software SPICE software to call.

[0025] Step 3: Add the single particle effect module to the model established in the TCAD software. After all parameters are set, perform single particle effect simulation on the device. You can get the single particle transient current curves under different LET values. Figure 6 As shown, it can be seen that the amplitude of the single-particle transient current increases with the increase of the LET value.

[0026] Step 3-1: Set the parameters of the single event effect module in the following order. Define the LET value of the incident particle as 3MeV·cm 2 / mg, 10MeV·cm 2 / mg, 25MeV·cm 2 / mg, 37MeV·cm 2 / mg, 50MeV·cm 2 / mg, 65MeV·cm 2 / mg, the incident and exit coordinates are (0.01, -0.02, -0.15) and (0.01, 0.4, -0.15) respectively, ensuring that the particles are incident vertically from the drain position of the device. After the heavy ion is incident, the spatial distribution diagram of the single particle upset generation rate of the device is as follows Figure 5 As shown, in addition, the incident particle track radius is set to 0.02 μm, and the characteristic time parameter and peak time parameter of charge generation are set to 4e-12 s and 2e-12 s, respectively.

[0027] Step 4: Fix the LET value of the particle to a certain value, change the incident coordinate and the exit coordinate of the ion, and obtain the single particle transient current at different incident angles.

[0028] Step 4-1: Refer to the following example for setting coordinates at different angles. Set the particle LET value to 37 MeV cm 2 / mg, when the coordinates are changed to (0.01, 0.00, -0.15) and (0.01, 0.4, 0.08), the single particle transient current with an incident angle of 30° is obtained. When the coordinates are changed to (0.01, 0.00, -0.15) and (0.01, 0.4, 0.25), the single particle transient current with an incident angle of 45° is obtained. The single particle transient current at the vertical incidence device drain is 0°, and the single particle transient current at this time has been obtained in step 3. Figure 7 Single particle transient current at 0°, 30°, and 45° incidence.

[0029] Step 5: Figure 8The figure shows the basic topology of SAR ADC. The working principle of SAR ADC is that the sampling and holding unit (which can be incorporated into the DAC capacitor array module) samples and holds the analog input signal VIN and uses it as an input of the comparator. Subsequently, the successive approximation register (SAR unit) starts the binary search algorithm. Initially, the highest bit (MSB) is set to "1" and the other bits are set to "0". Then the bit string (100...0) is added to the DAC capacitor array, so that the DAC output analog voltage is 1 / 2VREF, where VREF is the reference voltage of the SAR ADC. At this time, the analog voltage converted by the DAC is compared with the input signal VIN in the comparator. If VIN is greater than 1 / 2VREF, the comparator outputs a logic low level and the highest bit MSB remains "1"; if VIN is less than 1 / 2VREF, the comparator outputs a logic high level and the highest bit MSB is set to "0". After the highest bit is determined, keep the bit unchanged, set the second highest bit to "1", set the other bits to "0", and add the codeword to the DAC array, and compare again to determine the codeword of the second highest bit. This process is repeated until the least significant bit (LSB) is determined, and finally the digital code corresponding to the input signal VIN is obtained.

[0030] The circuit modeling of ADC is divided into three modules: DAC module, comparator module, and successive approximation logic module. Fig. 9 , Fig.10 , Fig.11 The following are the circuit structures of each module. According to the circuit structure, the circuit netlist file of each module is written using the circuit simulation software SPICE, and the library file extracted from TCAD is called to perform circuit simulation. Fig.12 , Fig.13 , Fig.14 The output waveform of each module is shown in Figure 2. After verifying the circuit function of each module, the circuit is connected as a whole. The reference voltage is set to 1.8V, the clock pulse period is 100ns, the sampling period of the comparator is 1400ns, and the analog input voltage is 1.5v. The circuit is simulated for a transient period of 4us with a time step of 1ns. When the analog input voltage is 1.5V, the output waveform of the ADC is as follows: Fig.15 As shown, it can be seen that the output of the ADC is 1101011000. According to the circuit principle of the successive approximation ADC: the theoretical value obtained after the binary output is converted into an analog output voltage = (D9*2 9 +D8*2 8 +D7*2 7 +D6*2 6 +D5*2 5 +D4*2 4 +D3*2 3 +D2*2 2 +D1*21 +D0*2 0 )*1.8 / 1024=1.5046V. The difference between the converted analog output voltage and the input voltage is within the allowable error range, completing the circuit modeling of the ADC device.

[0031] Step 6: According to the double exponential current source model Figure 6 The single-particle transient current curve data in is fitted to obtain its peak current, rise time, fall time, rise time constant and fall time constant. The double exponential function formula is shown in (1). (1) The parameters in the above formula are the current rising time (t r ), current rise time constant (τ α ), current drop time (t f ), current fall time constant (τ β ), peak current (I m ). The fault injection circuit is implemented in the form of current sources. The simulated output voltage changes of each node are compared and the most sensitive node net109 of the circuit is determined.

[0032] Step 7: Inject the single-particle transient current with different LET as a fault into the most sensitive node net109 of the circuit. When LET = 22 MeV·cm 2 / mg, the ADC output signal flipped, indicating a single-particle effect, but no flipping occurred before that. Therefore, the LET threshold of the circuit was determined to be 22 MeV·cm 2 / mg. Figure 6 Medium LET value is greater than 22 MeV·cm 2 / mg single-event transient current as fault injection net109, Fig.16 is the change in analog output voltage of ADC under different LET. It can be seen that the change in analog output voltage of ADC increases with the increase of LET. The larger the LET of the incident particles, the greater the destructiveness to the circuit.

[0033] Step 8: Fig.17 The figure shows the change in analog output voltage of the ADC at different incident angles. Fig.17The single-particle transient current in net109 is used as a fault injection. When the incident angle is 0°, the output signal of the ADC is 1011100111, the corresponding analog output is 1.3060V, and ΔVout is 0.198V. When the incident angle is 30°, the output signal of the ADC is 1011100000, the corresponding analog output is 1.29375V, and ΔVout is 0.21025V. When the incident angle is 45°, the output signal of the ADC is 1011001000, the corresponding analog output is 1.2516V, and ΔVout is 0.2524V. The output voltage change increases with the increase of the incident angle, and the damage to the device is the greatest at 45°.

[0034] Step 9: Fig.18 The figure shows the output voltage change of the ADC after injecting faults at different sensitive nodes. Injecting LET=37MeV·cm in the form of a double exponential current source 2 / mg single-particle transient pulse is defined as i2 net20 0exp(0 9.54m 150n 10n 200n 20n) in the SPICE model, that is, the initial value of the pulse current is 0, the amplitude current is i2, the rising edge start time of the pulse waveform is 150ns, the falling edge start time is 200ns, the rising edge time constant and the falling edge time constant of the waveform are 10ns and 20ns respectively, and the injection position is the sensitive nodes on the ten switch branches of the AD converter circuit DAC. These ten sensitive nodes correspond to the output signals D9-D0. The relationship between the position of the injected fault and the change in the ADC output voltage is obtained by transient simulation. It can be seen that when a single particle hits the sensitive node on the DAC switch branch, the higher the number of bits of the output signal controlled by the switch branch, the greater the impact on the ADC output.

[0035] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0036] Those skilled in the art will readily appreciate other embodiments of the invention after considering the specification and practicing the invention invented herein. This application is intended to cover any variations, uses or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art that are not invented by the present invention. The specification and examples are intended to be exemplary only, and the true scope and spirit of the invention are indicated by the claims.

[0037] The above specific implementation methods further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above are only specific implementation methods of the present application and are not used to limit the protection scope of the present application. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. A method for simulating single-particle effects of a successive approximation analog-to-digital converter, characterized in that: include: Based on the process parameters in the device product manual, three-dimensional modeling of the device in the ADC device is performed to generate the device structure; Conduct electrical modeling of the device structure, optimize the parameters of the device structure, and obtain electrical curves; Extract the parameter data of the optimized device structure as a library file; By performing single-particle effect simulation on the device structure, we can obtain single-particle transient current curves at different linear energy transfer values ​​and different angles.

2. The single event effect simulation method of a successive approximation analog-to-digital converter according to claim 1, characterized in that: Divide the overall circuit of the ADC device into several modules for circuit modeling, and compile and obtain the netlist file based on the library file; The obtained single-particle transient current curve data is fitted with a double exponential model, and the current source is injected into each node of the overall circuit of the ADC device. The output voltage changes before and after the injection of each node are compared to determine the most sensitive node.

3. The single event effect simulation method of a successive approximation analog-to-digital converter according to claim 2, characterized in that: Different linear energy transfer values ​​and single-particle transient currents at different angles are injected into the most sensitive node in the overall circuit of the ADC device to obtain the linear energy transfer threshold of the single-particle effect in the overall circuit of the ADC device and the influence of different linear energy transfer values ​​and different angles on the single-particle effect of the ADC device.

4. The single event effect simulation method of a successive approximation analog-to-digital converter according to claim 2, characterized in that: The several modules include a DAC module, a comparator module, and a successive approximation logic module.

5. The single event effect simulation method of a successive approximation analog-to-digital converter according to claim 4, characterized in that: The same single-particle transient current is injected into all the most sensitive nodes on the switch branches of the DAC module in the form of a current source, and the single-particle effect variation law of all the most sensitive node devices on the switch branches of the DAC module is obtained.

6. The single event effect simulation method of a successive approximation analog-to-digital converter according to claim 4, characterized in that: The parameters of the device structure include substrate, drift region, source region size and concentration.

7. The single event effect simulation method of a successive approximation analog-to-digital converter according to claim 4, characterized in that: The parameters of the incident particle in the single particle effect simulation include the LET value, incident position, exit position, track radius, characteristic time parameter and peak time of the incident particle.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the method according to any one of claims 1 to 7 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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