Transient characteristic simulation method and system for ibis model and computer device

Abstract

The application provides an IBIS model transient characteristic simulation method and system and a computer device, and the method comprises the following steps: reading I / V data and V / T data in an IBIS model file, and constructing an equivalent circuit equation based on KCL; judging the integrity of the V / T data, and adopting different algorithms for different pre-simulations according to different integrities of the V / T data, and calculating four current modulation parameters of a pull-up transistor PU and a pull-down transistor PD; and performing transient response simulation of the IBIS model according to the four current modulation parameters solved, and obtaining transient currents of the pull-up transistor PU and the pull-down transistor PD. The scheme solves the problem of poor adaptability of the prior art to different versions of IBIS models, and realizes IBIS transient characteristic simulation compatible with all versions.

Description

Technical Field

[0001] This invention relates to the field of device model simulation technology, and more particularly to a method, system and computer equipment for simulating the transient characteristics of an IBIS model. Background Technology

[0002] Advanced behavioral modeling is widely used to replace low-level transistor models to determine the behavior of input / output (I / O) drivers and receivers. IBIS (Input / Output Buffer Informational Specification) is one of the most widely used I / O driver modeling methods because it meets the basic requirements of behavioral models, such as IP protection, simple structure, fast simulation time, and reasonable accuracy.

[0003] IBIS provides I / V curves describing the steady-state characteristics of a buffer, including Power_Clamp, Gnd_Clamp, Pullup, and Pulldown, as well as V / T curves and ramp data describing transient characteristics, including Rising Waveform, Falling Waveform, and ramp. The I / V curve shows the impedance of the buffer in its fully on state, while the V / T curve describes the process of the I / V curve turning on or off over time.

[0004] However, in practical applications, IBIS models provided by different manufacturers vary significantly in the completeness of transient data, causing simulation algorithms to be incompatible with different versions of IBIS models and affecting the smooth progress of simulations. Therefore, there is an urgent need for a simulation method that can adapt to IBIS models of varying accuracy and achieve IBIS transient characteristic simulation that is compatible with all versions. Summary of the Invention

[0005] The purpose of this invention is to provide a method, system, and computer equipment for simulating the transient characteristics of IBIS models, thereby solving the problem of insufficient adaptability of existing technologies to different versions of IBIS models and realizing IBIS transient characteristic simulation that is compatible with all versions.

[0006] The technical solution provided by this invention is as follows:

[0007] Firstly, this application provides a method for simulating the transient characteristics of an IBIS model, comprising the following steps:

[0008] Read the I / V and V / T data from the IBIS model file and construct the equivalent circuit equations based on KCL;

[0009] Determine the integrity of the V / T data, and perform different pre-simulations based on the different integrity of the V / T data to calculate the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD. The different integrity of the V / T data includes any one of the following three cases: the V / T data has at least four sets, the V / T data has only two sets, and the ramp rate data exists but the V / T data does not exist.

[0010] Based on the solved current modulation parameters, the transient response simulation of the IBIS model is performed to obtain the transient currents of the pull-up transistor PU and the pull-down transistor PD.

[0011] In some implementations, the IBIS model includes a power clamping diode PC, a ground clamping diode GC, a pull-up transistor PU, and a pull-down transistor PD;

[0012] The equivalent circuit equation is:

[0013] ,

[0014] ,

[0015] in, , , , ;

[0016] The current at the output terminal OUT. The current modulation parameters for the pull-up transistor PU, The current modulation parameters for the pull-down transistor PD; The voltage for pulling up the transistor PU, The voltage for pulling down the transistor PD, This is the voltage of the power clamping diode PC. The voltage of the ground clamping diode GC; This refers to the branch current from the power supply clamp reference potential PC_ref to the output terminal out. This refers to the branch current from the ground clamping reference potential GC_ref to the output terminal out. This refers to the branch current from the pull-up reference potential PU_ref to the output terminal out. This refers to the branch current from the pull-down reference potential PD_ref to the output terminal out; To buffer the voltage at the output terminal, and The load conditions for the V / T data. and Together they form the output load circuit. This is the terminating power supply used when testing V / T data. It is a termination resistor. This is the equivalent parasitic capacitance.

[0017] In some embodiments, the current modulation parameters include a first current modulation parameter when the pull-up transistor PU is turned on, a second current modulation parameter when the pull-up transistor PU is turned off, a third current modulation parameter when the pull-down transistor PD is turned on, and a fourth current modulation parameter when the pull-down transistor PD is turned off.

[0018] When it is determined that there are at least four sets of V / T data, a set of calculation equations for the four current modulation parameters is constructed based on the V / T data and the equivalent circuit equation, and the four current modulation parameters are solved.

[0019] When it is determined that there are only two sets of V / T data, based on the complementary switching states of the pull-up transistor PU and the pull-down transistor PD, constraints are added for the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD. Based on the V / T data, the constraints, and the equivalent circuit equations, a set of calculation equations for the four current modulation parameters is constructed, and the four current modulation parameters are solved.

[0020] When it is determined that only the ramp rate data exists and the V / T data does not exist, four sets of V / T data are recovered based on the ramp rate data, and a set of calculation equations for the four current modulation parameters are constructed based on the four sets of V / T data and the equivalent circuit equations, and the four current modulation parameters are solved.

[0021] In some implementations, when it is determined that at least four sets of V / T data exist, the IBIS model includes a first load condition and a second load condition, and the calculation equations for the four current modulation parameters are as follows:

[0022] ,

[0023] ,

[0024] ,

[0025] ,

[0026] in, The first current modulation parameter, This is the second current modulation parameter. This is the third current modulation parameter. This is the fourth current modulation parameter; This is the output voltage when the first load condition flips from high to low. This refers to the output voltage when the second load condition flips from high to low. This is the output voltage when the first load condition flips from low to high. This is the output voltage when the second load condition flips from low to high.

[0027] In some embodiments, the constraints on the current modulation parameters of the pull-up transistor PU and the current modulation parameters of the pull-down transistor PD are as follows:

[0028] ,

[0029] ;

[0030] When it is determined that there are only two sets of V / T data, the IBIS model only includes the first load condition, and the calculation equations for the four current modulation parameters are as follows:

[0031] ,

[0032] ,

[0033] ,

[0034] ,

[0035] in, The first current modulation parameter, This is the second current modulation parameter. This is the third current modulation parameter. This is the fourth current modulation parameter; This is the output voltage when the first load condition flips from high to low. This is the output voltage when the first load condition flips from low to high.

[0036] In some implementations, when it is determined that only the ramp rate data exists and the V / T data does not exist, four sets of V / T data are recovered based on the ramp rate data, including the following steps:

[0037] Recover the first V / T data curve of the pull-up transistor PU from turn-on to complete turn-off based on the ramp rate data;

[0038] Recover the second V / T data curve of the pull-down transistor PD from off to fully on based on the ramp rate data;

[0039] The third V / T data curve of the pull-down transistor PD during the period from turn-on to complete turn-off is recovered based on the ramp rate data;

[0040] The fourth V / T data curve of the pull-up transistor PU during the period from off to fully on is recovered based on the ramp rate data;

[0041] Four sets of V / T data are obtained based on the first V / T data curve, the second V / T data curve, the third V / T data curve, and the fourth V / T data curve.

[0042] In some implementations, the ramp rate data includes the output rising edge. Data, and records and The ramp rate data also includes the output falling edge. Data, and records and ;

[0043] When calculating the first V / T data curve, the first maximum and first minimum values ​​of the output voltage of the pull-up transistor PU during the period from turn-on to complete turn-off are calculated based on the I / V data, and the difference between the first maximum and the first minimum values ​​is compared with... The magnitude relationship determines the linear and nonlinear regions of the first V / T data curve, and the linear and nonlinear regions of the first V / T data curve are recovered respectively.

[0044] When calculating the second V / T data curve, the second maximum and second minimum values ​​of the output voltage of the pull-down transistor PD during the period from off to fully on are calculated based on the I / V data, and the difference between the second maximum and the second minimum values ​​is compared with... The magnitude relationship determines the linear and nonlinear regions of the second V / T data curve, and the linear and nonlinear regions of the second V / T data curve are recovered respectively;

[0045] When calculating the third V / T data curve, the third maximum and third minimum values ​​of the output voltage of the pull-down transistor PD during its transition from turn-on to complete turn-off are calculated based on the I / V data, and the difference between the third maximum and the third minimum values ​​is compared with... The magnitude relationship determines the linear and nonlinear regions of the third V / T data curve, and the linear and nonlinear regions of the third V / T data curve are recovered respectively;

[0046] When calculating the fourth V / T data curve, the fourth maximum and fourth minimum values ​​of the output voltage of the pull-up transistor PU during the period from off to fully on are calculated based on the I / V data, and the difference between the fourth maximum and the fourth minimum values ​​is compared with... The magnitude relationship determines the linear and nonlinear regions of the fourth V / T data curve, and the linear and nonlinear regions of the fourth V / T data curve are restored respectively.

[0047] In some embodiments, obtaining the transient currents of the pull-up transistor PU and the pull-down transistor PD includes:

[0048] The I / V data of the pull-up transistor PU and the pull-down transistor PD at the current output voltage are multiplied by the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD in the corresponding states to obtain the transient current corresponding to the pull-up transistor PU and the pull-down transistor PD.

[0049] Secondly, this application provides an IBIS model transient characteristic simulation system, including a simulator, which executes the steps of the IBIS model transient characteristic simulation method described in the first aspect.

[0050] Thirdly, this application provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the IBIS model transient characteristic simulation method described in the first aspect.

[0051] The present invention provides an IBIS model transient characteristic simulation method, system, and computer device that can effectively handle IBIS models with different accuracy levels, including only Ramp data, two sets of V / T data, and multiple sets of V / T data, by automatically identifying the model data type and matching the corresponding calculation strategy. It constructs a unified simulation framework, which can solve the problem of insufficient adaptability of existing simulation systems to different versions of IBIS models, and is conducive to realizing IBIS transient characteristic simulation that is compatible with all versions. Attached Figure Description

[0052] The preferred embodiments will now be described in a clear and easy-to-understand manner, with reference to the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages, and implementation methods of this solution.

[0053] Figure 1 This is a schematic diagram of the overall process of one embodiment of the present invention;

[0054] Figure 2 This is a flowchart illustrating an embodiment of the present invention;

[0055] Figure 3 This is a flowchart illustrating an embodiment of the present invention;

[0056] Figure 4 This is an equivalent circuit schematic diagram of an IBIS model according to an embodiment of the present invention. Detailed Implementation

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0058] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of components with the same structure or function is shown schematically, or only one is labeled. In this document, "one" can mean not only "only one" but also "more than one".

[0059] Advanced behavioral modeling is widely used to replace low-level transistor models to determine the behavior of input / output (I / O) drivers and receivers. IBIS (Input / Output Buffer Informational Specification) is one of the most widely used I / O driver modeling methods because it meets the basic requirements of behavioral models, such as IP protection, simple structure, fast simulation time, and reasonable accuracy.

[0060] IBIS provides I / V curves describing the steady-state characteristics of the buffer, including Power_Clamp (the ESD diode of the chip pin to power supply VDD), Gnd_Clamp (the ESD diode of the chip pin to ground), the pull-up PMOS (or PNP) network in the Pullup output driver, and Pulldown (the pull-down NMOS (or NPN) network in the output driver), as well as V / T curves and ramp data describing transient characteristics, including Rising Waveform (the rising edge when Pullup is on and Pulldown is off), Falling Waveform (the falling edge when Pulldown is on and Pullup is off), and Ramp (the slew rate of the output rising and falling edges). The I / V curves show the impedance of the buffer in the fully on state, while the V / T curves describe the process of the I / V curve turning on or off over time. Typically, V / T data is converted to K / T data. When the simulator decides to change the state of the buffer, it uses these K / T tables to adjust the I / V curves. For example, for a transition from low to high, the pulldown I / V curve will be scaled from 100% to 0%, while the pullup I / V curve will be scaled from 0% to 100% over time, starting from the event that triggered the transition.

[0061] However, in practical applications, the IBIS models provided by different manufacturers vary significantly in the completeness of transient data, leading to incompatibility between simulation algorithms and different versions of IBIS models, thus affecting the smooth progress of simulations. For example, the early IBIS 1.0 version only required [Ramp] data; IBIS 2.1 introduced the keywords [Rising Waveform] and [Falling Waveform]; and IBIS 3.2 proposed that accurately describing the switching behavior of the buffer requires Rising Waveform and Falling Waveform curves corresponding to two different load conditions. Therefore, there is an urgent need for a simulation method that can adapt to IBIS models of different accuracies and achieve IBIS transient characteristic simulation that is compatible with all versions. The purpose of this invention is to provide a simulation method and system for the transient characteristics of IBIS models. By identifying IBIS models with different accuracy levels (such as those containing only Ramp data, single or multiple V / T tables), it automatically matches the pre-simulation algorithm, solving the problem of insufficient adaptability of existing technologies to different versions of IBIS models, and achieving IBIS transient characteristic simulation that is compatible with all versions. The following is a detailed description of this solution with reference to the accompanying drawings:

[0062] In one embodiment, refer to the appendix to the specification. Figure 1This application provides a method for simulating the transient characteristics of an IBIS model, including the following steps:

[0063] S10. Read the I / V and V / T data from the IBIS model file and construct the equivalent circuit equation based on KCL.

[0064] S20. Determine the integrity of the V / T data and perform different pre-simulations based on the different integrity of the V / T data. Calculate the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD. The different integrity of the V / T data includes any one of the following three cases: the V / T data has at least four sets, the V / T data has only two sets, and the ramp rate data exists but the V / T data does not exist.

[0065] S30. Perform transient response simulation of the IBIS model based on the solved current modulation parameters to obtain the transient currents of the pull-up transistor PU and the pull-down transistor PD.

[0066] For example, the equivalent circuit schematic of the IBIS model is as follows: Figure 4 As shown, the IBIS model includes a power clamp diode PC, a ground clamp diode GC, a pull-up transistor PU, and a pull-down transistor PD. Here, 'out' is the output terminal, PC_ref is the power clamp reference potential, GC_ref is the ground clamp reference potential, PU_ref is the pull-up reference potential, and PD_ref is the pull-down reference potential. This refers to the branch current from the power supply clamp reference potential PC_ref to the output terminal out. This refers to the branch current from the ground clamping reference potential GC_ref to the output terminal out. This refers to the branch current from the pull-up reference potential PU_ref to the output terminal out. This is the branch current from the pull-down reference potential PD_ref to the output terminal out.

[0067] The I / V data in the IBIS model file, i.e., static data, includes Power_Clamp, Gnd_Clamp, Pullup, and Pulldown; while the V / T data is transient data, including Rising / Falling Waveform and Ramp data. Static data is composed of... The corresponding DC current composition for various voltage values. The Power_Clamp table lists... and The relationship between the voltage difference and the power supply clamp reference potential is listed in the Gnd_Clamp table. and The relationship between the voltage difference between the ground clamping reference potential and the ground clamping potential is listed in the Pullup table. and The relationship between the voltage difference and the pull-up reference potential is listed in the Pulldown table. and The relationship between the voltage difference and the pull-down reference potential. Transient data is expressed as a V / T meter or ramp rate. V / T data is expressed under different load conditions. , Under the conditions, A dynamic table of the rise and fall waveforms of transient information that varies with time. The ramp rate, represented by the [Ramp] keyword, indicates the slew rate of the output rise and fall edges, i.e., the time required for the voltage output amplitude to decrease from 20% to 80%, or from 80% to 20%. The IBIS model simulation algorithm uses time-varying multiplication to link the static I / V and dynamic V / T data tables, describing the switching behavior of pull-up and pull-down transistors respectively. Parameters and It depends on the dynamic behavior of the device, and is used as the current. and The multiplicative factor.

[0068] The equivalent circuit equation for Kirchhoff's current law at node out can be expressed as:

[0069] ,

[0070] ,

[0071] in, , , , ;

[0072] The current at the output terminal OUT. The current modulation parameters for the pull-up transistor PU, The current modulation parameters for the pull-down transistor PD; The voltage for pulling up the transistor PU, The voltage for pulling down the transistor PD, This is the voltage of the power clamping diode PC. The voltage of the ground clamping diode GC; To buffer the voltage at the output terminal, and The load conditions for the V / T data. and Together they form the output load circuit. This is the terminating power supply used when testing V / T data. It is a termination resistor. This is the equivalent parasitic capacitance. The question then becomes: how to obtain the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD? and This is the key to modeling the transient characteristics of the IBIS model.

[0073] In one embodiment, refer to the appendix to the specification. Figure 2 and attached Figure 3 This application provides a method for simulating the transient characteristics of an IBIS model, including the following steps:

[0074] S100: Read the I / V and V / T data from the IBIS model file and construct the equivalent circuit equation based on KCL.

[0075] S200. Determine the integrity of the V / T data and perform different pre-simulations based on the different integrity of the V / T data. Calculate the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD. The different integrity of the V / T data includes any one of the following three cases: the V / T data has at least four sets, the V / T data has only two sets, and the ramp rate data exists but the V / T data does not exist.

[0076] S300. When it is determined that there are at least four sets of V / T data, construct a set of calculation equations for four current modulation parameters based on the V / T data and the equivalent circuit equations, and solve for the four current modulation parameters.

[0077] S400. When it is determined that there are only two sets of V / T data, based on the complementary switching states of the pull-up transistor PU and the pull-down transistor PD, constraints are added for the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD. Based on the V / T data, constraints, and equivalent circuit equations, a set of calculation equations for the four current modulation parameters is constructed, and the four current modulation parameters are solved.

[0078] S500. When it is determined that only ramp rate data exists but V / T data does not exist, four sets of V / T data are recovered based on the ramp rate data. Based on the four sets of V / T data and the equivalent circuit equation, a set of calculation equations for four current modulation parameters is constructed, and the four current modulation parameters are solved.

[0079] S600. Based on the four current modulation parameters obtained, perform transient response simulation of the IBIS model to obtain the transient currents of the pull-up transistor PU and the pull-down transistor PD.

[0080] Specifically, the current modulation parameters include a first current modulation parameter when the pull-up transistor PU is turned on, a second current modulation parameter when the pull-up transistor PU is turned off, a third current modulation parameter when the pull-down transistor PD is turned on, and a fourth current modulation parameter when the pull-down transistor PD is turned off.

[0081] This solution can automatically identify the data type of the IBIS model and match the corresponding calculation strategy. It judges the integrity of the V / T data and uses different algorithms for different pre-simulations based on the different levels of V / T data integrity. The data type of the IBIS model can specifically include only ramp data, two sets of V / T data, and multiple sets of V / T data. This classification is because in the most widely used IBIS 3.2 version, the transient response of the IBIS model is described by four sets of V / T data corresponding to different load conditions; while in earlier versions of IBIS, the transient response of the IBIS model only recorded one set of falling waveform and rising waveform under one load condition, i.e., two sets of V / T data. Furthermore, since the IBIS specification only stipulates that the keyword [Ramp] is mandatory, while the keywords [rising waveform] and [falling waveform] are optional, in practical applications, some IBIS models only provide ramp data. Therefore, this application classifies the V / T data integrity into three categories: only ramp data, two sets of V / T data, and multiple sets (at least four sets) of V / T data.

[0082] When the output voltage level transitions from high to low, the PD device gradually turns from off to on, and the PU device gradually turns from on to off; when the output voltage level transitions from low to high, the PU device gradually turns from off to on, and the PD device gradually turns from on to off. Therefore, the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD are divided into four types, which are the first current modulation parameters when the pull-up transistor PU is on. Second current modulation parameters when the pull-up transistor PU is turned off The third current modulation parameter when the pull-down transistor PD is turned on. and the fourth current modulation parameter when the pull-down transistor PD is turned off .

[0083] In the most widely used version of IBIS, 3.2, the transient response of the IBIS model is described by four sets of V / T data corresponding to different load conditions, as shown in the table below:

[0084]

[0085] The IBIS model includes the first load condition and the second load condition, and the calculation equations for the four current modulation parameters are as follows:

[0086] ,

[0087] ,

[0088] ,

[0089] ,

[0090] in, The first current modulation parameter, This is the second current modulation parameter. This is the third current modulation parameter. This is the fourth current modulation parameter; This is the output voltage when the first load condition flips from high to low. This refers to the output voltage when the second load condition flips from high to low. This is the output voltage when the first load condition flips from low to high. This represents the output voltage when the second load condition flips from low to high. By solving the above equations, the four current modulation parameters of the pull-up transistor PU and the pull-down transistor PD can be calculated.

[0091] In early versions of IBIS, the transient response of the IBIS model only recorded the falling and rising waveforms under one set of load conditions, resulting in only one VT curve. However, there were two modulation parameters for each of the PU and PD devices. Therefore, it was necessary to find an approximate relationship between the PU and PD modulation parameters. For the transition from low to high level, at time zero, the PU device is completely off and the PD device is completely on. After reaching steady state, the PU device is completely on and the PD device is completely off. Therefore, during the switching process, the switching states of the PU and PD devices can be approximated as complementary, and can be approximately represented as follows:

[0092] ,

[0093] The same principle applies to the transition from high to low level. Therefore, this application can add constraints on the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD based on the complementary switching states of the pull-up transistor PU and the pull-down transistor PD:

[0094] ,

[0095] .

[0096] When it is determined that there are only two sets of V / T data, the IBIS model only includes the first load condition, and the calculation equations for the four current modulation parameters are as follows:

[0097] ,

[0098] ,

[0099] ,

[0100] ,

[0101] in, The first current modulation parameter, This is the second current modulation parameter. This is the third current modulation parameter. This is the fourth current modulation parameter; This is the output voltage when the first load condition flips from high to low. This represents the output voltage when the first load condition flips from low to high. By solving the above equations, the four current modulation parameters of the pull-up transistor PU and the pull-down transistor PD can be calculated.

[0102] Since the IBIS specification only stipulates that the keyword [Ramp] is mandatory, while the keywords [rising waveform] and [falling waveform] are optional, in practical applications, some IBIS models only provide ramp data, so it is necessary to recover the corresponding V / T curve based on the ramp data.

[0103] Ramp rate data describes and Two parameters. Rise time is defined as the time it takes for the signal's rising edge to change from 20% to 80%, measured by placing a termination resistor for testing from the output to GND. This is achieved by switching the output from low to high. The fall time is defined as the time it takes for the signal's falling edge to change from 80% to 20%, measured by placing a termination resistor for testing between the output and VCC. This is achieved by switching the output from high to low. Therefore, the ramp rate data includes the output rising edge. Data, recorded in this solution and The ramp rate data also includes the output falling edge. Data, recorded in this solution and .

[0104] When it is determined that only slope rate data exists but V / T data does not, the specific steps for recovering four sets of V / T data based on the slope rate data are as follows:

[0105] S510: Recover the first V / T data curve of the pull-up transistor PU from turn-on to full turn-off based on the ramp rate data.

[0106] When calculating the first V / T data curve, the first maximum and first minimum values ​​of the output voltage of the pull-up transistor PU during the period from turn-on to full turn-off are calculated based on the I / V data, and the difference between the first maximum and first minimum values ​​is then compared with... The magnitude relationship determines the linear and nonlinear regions of the first V / T data curve, and the linear and nonlinear regions of the first V / T data curve are restored respectively.

[0107] Specifically, reading The data are denoted as follows: and Calculate the maximum output voltage of the pull-up transistor PU device from turn-on to complete turn-off based on its static I / V characteristics. and minimum value . When the output is connected to GND Output voltage when reduced to 0 When the output is connected to GND The output voltage when it decreases to 0.

[0108] judge , and The size relationship, if This indicates that the measured ramp data of this IBIS does not meet the requirements. Given a voltage output amplitude defined as approximately 80%-20%, the following adjustments are made:

[0109] ,

[0110] ,

[0111] ;

[0112] The recovered V / T curve is divided into a linear region and a nonlinear region. The linear region is where the voltage transitions from... arrive The range, the slope is The nonlinear region is where the voltage changes from... arrive The range is fitted using complementary error functions. Determined by the following formula:

[0113] Linear region: ;

[0114] Nonlinear region:

[0115] ;

[0116] in, Defined as The minimum time. The V / T curve recovered at this point is the first V / T data curve, marked as... .

[0117] S520: Recover the second V / T data curve of the pull-down transistor PD from off to fully on based on the ramp rate data.

[0118] When calculating the second V / T data curve, the second maximum and second minimum values ​​of the output voltage of the pull-down transistor PD during its transition from off to fully on are calculated based on the I / V data. The difference between the second maximum and second minimum values ​​is then compared with... The magnitude relationship determines the linear and nonlinear regions of the second V / T data curve, and the linear and nonlinear regions of the second V / T data curve are restored respectively.

[0119] Specifically, reading The data are denoted as follows: and Calculate the maximum output voltage of the pull-down transistor PD from off to fully on based on its static I / V characteristics. and minimum value . When the output is connected to VCC Output voltage when reduced to 0 When the output is connected to VCC The output voltage when it decreases to 0.

[0120] judge , and The size relationship, if This indicates that the measured ramp data of this IBIS does not meet the requirements. Given a voltage output amplitude defined as approximately 80%-20%, the following adjustments are made:

[0121] ,

[0122] ,

[0123] ;

[0124] The recovered V / T curve is divided into a linear region and a nonlinear region. The linear region is where the voltage transitions from... arrive The range, the slope is The nonlinear region is where the voltage changes from... arrive The range is fitted using complementary error functions. Determined by the following formula:

[0125] Linear region: ;

[0126] Nonlinear region:

[0127] ;

[0128] in, Defined as The minimum time. The recovered V / T curve at this point is the second V / T data curve, marked as... .

[0129] S530: Recover the third V / T data curve of the pull-down transistor PD from turn-on to full turn-off based on the ramp rate data.

[0130] When calculating the third V / T data curve, the third maximum and third minimum values ​​of the output voltage of the pull-down transistor PD during its transition from turn-on to complete turn-off are calculated based on the I / V data. The difference between the third maximum and third minimum values ​​is then compared with... The magnitude relationship determines the linear and nonlinear regions of the third V / T data curve, and the linear and nonlinear regions of the third V / T data curve are restored respectively.

[0131] Specifically, reading The data are denoted as follows: and Calculate the maximum output voltage of the pull-down transistor PD from turn-on to fully turn-off based on its static I / V characteristics. and minimum value . When the output is connected to VCC Output voltage when reduced to 0 When the output is connected to VCC The output voltage when it decreases to 0.

[0132] judge , and The size relationship, if This indicates that the measured ramp data of this IBIS does not meet the requirements. Given a voltage output amplitude defined as approximately 20%-80%, the following adjustments are made:

[0133] ,

[0134] ,

[0135] ;

[0136] The recovered V / T curve is divided into a linear region and a nonlinear region. The linear region is where the voltage transitions from... arrive The range, the slope is The nonlinear region is where the voltage changes from... arrive The range is fitted using complementary error functions. Determined by the following formula:

[0137] Linear region: ;

[0138] Nonlinear region:

[0139] ;

[0140] in, Defined as The minimum time. The recovered V / T curve at this point is the third V / T data curve, marked as... .

[0141] S540: Recover the fourth V / T data curve of the pull-up transistor PU from off to fully on based on the ramp rate data.

[0142] When calculating the fourth V / T data curve, the fourth maximum and fourth minimum values ​​of the output voltage of the pull-up transistor PU during the period from off-state to full on-state are calculated based on the I / V data. The difference between the fourth maximum and fourth minimum values ​​is then compared with... The magnitude relationship determines the linear and nonlinear regions of the fourth V / T data curve, and the linear and nonlinear regions of the fourth V / T data curve are restored respectively.

[0143] Specifically, reading The data are denoted as follows: and Calculate the maximum output voltage of the pull-up transistor PU during the period from off to fully on based on its static I / V characteristics. and minimum value . When the output is connected to GND Output voltage when reduced to 0 When the output is connected to GND The output voltage when it decreases to 0.

[0144] judge , and The size relationship, if This indicates that the measured ramp data of this IBIS does not meet the requirements. Given a voltage output amplitude defined as approximately 20%-80%, the following adjustments are made:

[0145] ,

[0146] ,

[0147] ;

[0148] The recovered V / T curve is divided into a linear region and a nonlinear region. The linear region is where the voltage transitions from... arrive The range, the slope is The nonlinear region is where the voltage changes from... arrive The range is fitted using complementary error functions. Determined by the following formula:

[0149] Linear region: ;

[0150] Nonlinear region:

[0151] ;

[0152] in, Defined as The minimum time. The recovered V / T curve at this point is the fourth V / T data curve, marked as... .

[0153] S550. Obtain four sets of V / T data based on the first V / T data curve, the second V / T data curve, the third V / T data curve, and the fourth V / T data curve.

[0154] This invention reconstructed four sets of V / T curves based on [Ramp] data. , , and Based on the aforementioned method for calculating modulation parameters when at least four sets of V / T data exist, the corresponding four modulation parameters can be calculated. , , and .

[0155] After calculating the four modulation parameters of the pull-up transistor PU and pull-down transistor PD using the above calculation method for different IBIS models, the transient currents of the pull-up transistor PU and pull-down transistor PD are obtained through IBIS model transient characteristic simulation, specifically including:

[0156] Multiply the I / V data of the pull-up transistor PU and the pull-down transistor PD at the current output voltage with the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD in the corresponding states to obtain the transient currents corresponding to the pull-up transistor PU and the pull-down transistor PD.

[0157] Specifically, the transient current of the pull-up transistor PU and the pull-down transistor PD is equal to the product of the steady-state current I / V at the current output voltage and the corresponding modulation coefficient. Specifically, if the pull-up transistor PU gradually transitions from on to off, the transient current of the pull-up transistor PU is... If the pull-up transistor PU gradually switches from off to on, the transient current of the pull-up transistor PU is: If the pull-down transistor PD device gradually transitions from on to off, the transient current of the pull-down transistor PD device is: If the pull-down transistor PD device gradually transitions from off to on, the transient current of the pull-down transistor PD device is: . , The voltage is calculated using the aforementioned KCL equation. Real-time current modulation parameters are obtained by looking up a table. The transient currents of the pull-up transistor PU and pull-down transistor PD are then obtained by multiplying the modulation coefficients by the steady-state I / V data of PU and PD.

[0158] This solution identifies IBIS models with different accuracy levels (such as those containing only Ramp data, or single or multiple V / T tables) and automatically matches them with pre-simulation algorithms. This solves the problem of insufficient adaptability of existing technologies to different versions of IBIS models and enables IBIS transient characteristic simulation that is compatible with all versions.

[0159] In one embodiment, based on the foregoing embodiments, this application provides an IBIS model transient characteristic simulation system, including a simulator, which executes the steps of the IBIS model transient characteristic simulation method of the foregoing embodiments.

[0160] In one embodiment, based on the foregoing embodiments, this application provides a computer device including a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the steps of the IBIS model transient characteristic simulation method of the foregoing embodiments.

[0161] In one embodiment, based on the foregoing embodiments, this application provides a computer storage medium storing a computer program or instructions, wherein the computer program or instructions, when executed by a processor, implement the steps of the IBIS model transient characteristic simulation method of the foregoing embodiments.

[0162] In one embodiment, based on the foregoing embodiments, this application provides a computer program product, including a computer program or instructions, which, when executed by a processor, implement the steps of the IBIS model transient characteristic simulation method of the foregoing embodiments.

[0163] The IBIS model transient characteristic simulation method of this application can be implemented using computer-executable program code. Therefore, these code snippets can be stored in a storage device for execution by a computing device, or they can be fabricated as individual integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this invention is not limited to any particular hardware and software combination.

[0164] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for simulating the transient characteristics of an IBIS model, characterized in that, Including the following steps: Read the I / V and V / T data from the IBIS model file and construct the equivalent circuit equations based on KCL; Determine the integrity of the V / T data, and perform different pre-simulations based on the different integrity of the V / T data to calculate the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD. The different integrity of the V / T data includes any one of the following three cases: the V / T data has at least four sets, the V / T data has only two sets, and the ramp rate data exists but the V / T data does not exist. Based on the solved current modulation parameters, the transient response simulation of the IBIS model is performed to obtain the transient currents of the pull-up transistor PU and the pull-down transistor PD.

2. The IBIS model transient characteristic simulation method according to claim 1, characterized in that, The IBIS model includes a power clamping diode PC, a ground clamping diode GC, a pull-up transistor PU, and a pull-down transistor PD. The equivalent circuit equation is: ， ， in, , , , ; The current at the output terminal OUT. The current modulation parameters for the pull-up transistor PU, The current modulation parameters for the pull-down transistor PD; The voltage for pulling up the transistor PU, The voltage for pulling down the transistor PD, This is the voltage of the power clamping diode PC. The voltage of the ground clamping diode GC; This refers to the branch current from the power supply clamp reference potential PC_ref to the output terminal out. This refers to the branch current from the ground clamping reference potential GC_ref to the output terminal out. This refers to the branch current from the pull-up reference potential PU_ref to the output terminal out. This refers to the branch current from the pull-down reference potential PD_ref to the output terminal out; To buffer the voltage at the output terminal, and The load conditions for the V / T data. and Together they form the output load circuit. This is the terminating power supply used when testing V / T data. It is a termination resistor. This is the equivalent parasitic capacitance.

3. The IBIS model transient characteristic simulation method according to claim 2, characterized in that, The current modulation parameters include a first current modulation parameter when the pull-up transistor PU is turned on, a second current modulation parameter when the pull-up transistor PU is turned off, a third current modulation parameter when the pull-down transistor PD is turned on, and a fourth current modulation parameter when the pull-down transistor PD is turned off. When it is determined that there are at least four sets of V / T data, a set of calculation equations for the four current modulation parameters is constructed based on the V / T data and the equivalent circuit equation, and the four current modulation parameters are solved. When it is determined that there are only two sets of V / T data, based on the complementary switching states of the pull-up transistor PU and the pull-down transistor PD, constraints are added for the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD. Based on the V / T data, the constraints, and the equivalent circuit equations, a set of calculation equations for the four current modulation parameters is constructed, and the four current modulation parameters are solved. When it is determined that only the ramp rate data exists and the V / T data does not exist, four sets of V / T data are recovered based on the ramp rate data, and a set of calculation equations for the four current modulation parameters are constructed based on the four sets of V / T data and the equivalent circuit equations, and the four current modulation parameters are solved.

4. The IBIS model transient characteristic simulation method according to claim 3, characterized in that, When it is determined that there are at least four sets of V / T data, the IBIS model includes a first load condition and a second load condition, and the calculation equations for the four current modulation parameters are as follows: ， ， ， ， in, The first current modulation parameter, This is the second current modulation parameter. This is the third current modulation parameter. This is the fourth current modulation parameter; This is the output voltage when the first load condition flips from high to low. This refers to the output voltage when the second load condition flips from high to low. This is the output voltage when the first load condition flips from low to high. This is the output voltage when the second load condition flips from low to high.

5. The IBIS model transient characteristic simulation method according to claim 3, characterized in that, The constraints on the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD are as follows: ， ； When it is determined that there are only two sets of V / T data, the IBIS model only includes the first load condition, and the calculation equations for the four current modulation parameters are as follows: ， ， ， ， in, The first current modulation parameter, This is the second current modulation parameter. This is the third current modulation parameter. This is the fourth current modulation parameter; This is the output voltage when the first load condition flips from high to low. This is the output voltage when the first load condition flips from low to high.

6. The IBIS model transient characteristic simulation method according to claim 3, characterized in that, When it is determined that only the ramp rate data exists and the V / T data does not exist, the four sets of V / T data are recovered based on the ramp rate data, including the following steps: Recover the first V / T data curve of the pull-up transistor PU from turn-on to complete turn-off based on the ramp rate data; Recover the second V / T data curve of the pull-down transistor PD from off to fully on based on the ramp rate data; The third V / T data curve of the pull-down transistor PD during the period from turn-on to complete turn-off is recovered based on the ramp rate data; The fourth V / T data curve of the pull-up transistor PU during the period from off to fully on is recovered based on the ramp rate data; Four sets of V / T data are obtained based on the first V / T data curve, the second V / T data curve, the third V / T data curve, and the fourth V / T data curve.

7. The IBIS model transient characteristic simulation method according to claim 6, characterized in that, The ramp rate data includes the output rising edge. Data, and records and The ramp rate data also includes the output falling edge. Data, and records and ; When calculating the first V / T data curve, the first maximum and first minimum values ​​of the output voltage of the pull-up transistor PU during the period from turn-on to complete turn-off are calculated based on the I / V data, and the difference between the first maximum and the first minimum values ​​is compared with... The magnitude relationship determines the linear and nonlinear regions of the first V / T data curve, and the linear and nonlinear regions of the first V / T data curve are recovered respectively. When calculating the second V / T data curve, the second maximum and second minimum values ​​of the output voltage of the pull-down transistor PD during the period from off to fully on are calculated based on the I / V data, and the difference between the second maximum and the second minimum values ​​is compared with... The magnitude relationship determines the linear and nonlinear regions of the second V / T data curve, and the linear and nonlinear regions of the second V / T data curve are recovered respectively; When calculating the third V / T data curve, the third maximum and third minimum values ​​of the output voltage of the pull-down transistor PD during its transition from turn-on to complete turn-off are calculated based on the I / V data, and the difference between the third maximum and the third minimum values ​​is compared with... The magnitude relationship determines the linear and nonlinear regions of the third V / T data curve, and the linear and nonlinear regions of the third V / T data curve are recovered respectively; When calculating the fourth V / T data curve, the fourth maximum and fourth minimum values ​​of the output voltage of the pull-up transistor PU during the period from off to fully on are calculated based on the I / V data, and the difference between the fourth maximum and the fourth minimum values ​​is compared with... The magnitude relationship determines the linear and nonlinear regions of the fourth V / T data curve, and the linear and nonlinear regions of the fourth V / T data curve are restored respectively.

8. The IBIS model transient characteristic simulation method according to claim 1, characterized in that, The process of obtaining the transient currents of the pull-up transistor PU and the pull-down transistor PD includes: The I / V data of the pull-up transistor PU and the pull-down transistor PD at the current output voltage are multiplied by the current modulation parameters of the pull-up transistor PU and the pull-down transistor PD in the corresponding states to obtain the transient current corresponding to the pull-up transistor PU and the pull-down transistor PD.

9. A transient characteristic simulation system for an IBIS model, characterized in that, Includes a simulator that performs the steps of the IBIS model transient characteristic simulation method according to any one of claims 1-8.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the IBIS model transient characteristic simulation method according to any one of claims 1-8.

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