BJT device mismatch model and extraction method thereof
By adding parameter mismatch functions for small and large injection current regions to the BJT device mismatch model, the problem of inaccurate mismatch characteristics of existing models under different operating conditions is solved, improving the accuracy and applicability of the model and ensuring the stability of circuit performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI HUALI INTEGRATED CIRCUIT CORP
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-19
AI Technical Summary
Existing BJT device mismatch models cannot accurately reflect the mismatch characteristics of devices under various operating conditions, especially in the small injection current region and the large injection current region, which affects the accuracy and stability of circuit performance.
A BJT device mismatch model is proposed, which includes parameter mismatch functions for the small injection current region, the linear current region, and the large injection current region. By adding a second and a third type of parameter mismatch function for the small injection current region and the large injection current region to the existing linear current region, the model accuracy is improved by adjusting the parameters using fitting coefficients.
It achieves accurate response to the mismatch characteristics of BJT devices under different operating current conditions, improves the modeling accuracy and applicability, and ensures the stability and reliability of circuit performance.
Smart Images
Figure CN122065748A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor integrated circuit manufacturing, and particularly to a BJT device mismatch model. This invention also relates to a method for extracting the BJT device mismatch model. Background Technology
[0002] In semiconductor manufacturing, processes such as photolithography and doping inevitably introduce random variations. Even when manufacturing the same type of BJT device on the same chip, parameters such as reverse saturation current and emitter coefficient will differ. These parameter mismatches can lead to variations in circuit performance, affecting the circuit's accuracy and stability. With the development of integrated circuit technology, the complexity of circuits and the performance requirements are constantly increasing. The impact of BJT mismatch on circuit performance is becoming increasingly significant. Therefore, it is necessary to establish accurate mismatch models to predict and compensate for these effects, thereby improving the reliability and performance of circuit designs.
[0003] As the requirements for circuit performance increase, engineers have begun to study the mismatch characteristics of BJTs. However, the current BJT mismatch models are still lacking. The current BJT models mainly focus on the parameter mismatch of the device under a single operating condition, and cannot simultaneously observe the mismatch of BJTs under multiple operating conditions.
[0004] like Figure 1 The diagram shown is an architecture diagram of the existing BJT device mismatch model; the device mismatch model 101 includes: Beta mismatch model 102, Vbe mismatch model 103, is mismatch function 104 and bf mismatch function 105.
[0005] Beta is the current gain, and the formula for the Beta mismatch model 102 is as follows: Delta Beta =2*(Beta1-Beta2) / (Beta1+Beta2); Where Beta1 and Beta2 are two pairs of Beta and Delta of the BJT devices. Beta The mismatch rate between the Beta of the two paired BJT devices is denoted as .
[0006] Vbe is the base-emitter voltage, and the formula for the Vbe mismatch model 103 is as follows: Delta Vbe =Vbe1-Vbe2; Wherein, Vbe1 and Vbe2 are two pairs of Vbe and Delta of the BJT device. Vbe The mismatch rate between the Vbe values of the two paired BJT devices is denoted as Vbe.
[0007] is is the collector saturation current, and the formula for the mismatch function 104 is is: f_Mis(is)=1+A*[1 / sqrt(Area_E)]; bf is the forward current gain, and the formula for the bf mismatch function 105 is: f_Mis(bf)=1+B*[1 / sqrt(Area_E)].
[0008] Where f_Mis(is) represents the is mismatch function, A is the fitting coefficient, and Area_E is the effective emitter area. f_Mis(bf) represents the bf mismatch function, and B is the fitting coefficient.
[0009] After A and B are determined through fitting, simulation can yield the fitted curve, such as... Figures 2 to 7 The figure shows the fitting curve of the existing BJT device mismatch model; where, Figures 2 to 4 Both curves represent the model simulation curves and target curves between the mismatch rates between Beta values, i.e., Sigma (Beta) and 1 / sqrt(AREA). AREA is an abbreviation for Area_E, and 1 / sqrt(AREA) is the reciprocal of the square root of the effective emitter area. Figures 2 to 4 The corresponding temperatures are all 25℃, and the emitter currents (IE) are respectively: Figure 2 In this case, IE = 1.578e-009A, which falls within the small injection current region; Figure 3 In this case, IE = 1.000e-006A, which falls within the linear current region; Figure 4 In this case, IE = 1.578e-005A; this falls within the large injection current region. It can be seen that... Figure 2 In the simulation, the model curve 201a and the target curve 201b are different, therefore the model simulation is inaccurate. Figure 3 In the simulation, the model curve and the target curve basically coincide, so the model simulation in the linear current region is accurate. Figure 4 In the simulation, curve 202a and the target curve 202b differ, indicating inaccuracy in the model simulation. Therefore, the model simulation results for the mismatch rate of Beta are only accurate in the linear current region, and are inaccurate in both the small and large injection current regions.
[0010] Figures 5 to 7 Both are model simulation curves and target curves representing the mismatch rate between Vbe, i.e., Sigma(Vbe) and 1 / sqrt(AREA). Figures 5 to 7 The corresponding temperatures are all 25℃, and the emitter currents (IE) are respectively: Figure 5 In this case, IE = 1.578e-009A, which falls within the small injection current region. Figure 6 In this case, IE = 1.000e-006A, which falls within the linear current region. Figure 7 In this case, IE = 1.578e-005A; it belongs to the large injection current region. It can be seen that... Figure 5 In the simulation, the model curve 203a and the target curve 203b are different, therefore the model simulation is inaccurate. Figure 6 In the simulation, the model curve and the target curve basically coincide, so the model simulation in the linear current region is accurate. Figure 7 In the simulation, curve 204a and the target curve 204b differ, indicating inaccuracy in the model simulation. Therefore, the model simulation results for the mismatch rate of Vbe are only accurate in the linear current region, and are inaccurate in both the small and large injection current regions. Summary of the Invention
[0011] The technical problem to be solved by this invention is to provide a BJT device mismatch model that can accurately reflect the mismatch characteristics of BJT devices under different operating currents, thereby improving modeling accuracy. To this end, this invention also provides a method for extracting the BJT device mismatch model.
[0012] To solve the above technical problems, the BJT device mismatch model provided by the present invention includes the following working regions of the BJT device: a small injection current region, a linear current region, and a large injection current region; the current in the small injection current region is less than the current in the linear current region, and the current in the large injection current region is greater than the current in the linear current region.
[0013] Device mismatch models include: Beta mismatch model, Vbe mismatch model, first type parameter mismatch function, second type parameter mismatch function, and third type parameter mismatch function.
[0014] The first type of parameter mismatch function is a function between the mismatch value of the first type of parameter in the linear current region and the effective area of the emitter.
[0015] The second type of parameter mismatch function is a function between the mismatch value of the second type of parameter in the small injection current region and the effective area of the emitter.
[0016] The third type of parameter mismatch function is a function between the mismatch value of the third type of parameter in the large injection current region and the effective area of the emitter.
[0017] Beta is the current gain, and the formula for the Beta mismatch model is: Delta Beta =2*(Beta1-Beta2) / (Beta1+Beta2); Where Beta1 and Beta2 are two pairs of Beta and Delta of the BJT devices. BetaThe mismatch rate between the Beta of the two paired BJT devices is denoted as .
[0018] Vbe is the base-emitter voltage, and the formula for the Vbe mismatch model is: Delta Vbe =Vbe1-Vbe2; Wherein, Vbe1 and Vbe2 are two pairs of Vbe and Delta of the BJT device. Vbe The mismatch rate between the Vbe values of the two paired BJT devices is denoted as Vbe.
[0019] A further improvement is that the first type of parameter includes is and bf.
[0020] is is the collector saturation current.
[0021] bf is the forward current gain.
[0022] A further improvement is that the second type of parameter includes ise and ne.
[0023] ise is the reverse saturation current of the emitter junction.
[0024] ne represents the base-emitting system.
[0025] A further improvement is that the third type of parameter includes rb.
[0026] rb is the base region resistance.
[0027] A further improvement is that the formula for the first type of parameter mismatch function includes: f_Mis(is)=1+A*[1 / sqrt(Area_E)].
[0028] f_Mis(bf)=1+B*[1 / sqrt(Area_E)].
[0029] Where f_Mis(is) represents the mismatch function of is, A is the fitting coefficient, and Area_E is the effective emitter area.
[0030] f_Mis(bf) represents the mismatch function of bf, where B is the fitting coefficient.
[0031] A further improvement is that the formula for the second type of parameter mismatch function includes: f_Mis(ise)=1+C*[1 / sqrt(Area_E)].
[0032] f_Mis(ne)=1+D*[1 / sqrt(Area_E)].
[0033] Where f_Mis(ise) represents the mismatch function of ise, and C is the fitting coefficient.
[0034] f_Mis(ne) represents the mismatch function of ne, and D is the fitting coefficient.
[0035] A further improvement is that the formula for the third type of parameter mismatch function includes: f_Mis(rb)=1+E*[1 / sqrt(Area_E)].
[0036] Where f_Mis(rb) represents the mismatch function of rb, and E is the fitting coefficient.
[0037] To address the aforementioned technical problems, the method for extracting the BJT device mismatch model provided by this invention includes the following steps: Step 1: Fabricate BJT devices on a wafer and perform measurements to obtain measurement data for pairs of BJT devices.
[0038] Step 2: Filter the measurement data.
[0039] Step 3: Calculate the mismatch rate of each parameter of the BJT device; the parameters include: Beta, Vbe, a first type parameter, a second type parameter, and a third type parameter; the operating region of the BJT device includes: a small injection current region, a linear current region, and a large injection current region; the current in the small injection current region is less than the current in the linear current region, and the current in the large injection current region is greater than the current in the linear current region; the first type parameter is the parameter of the linear current region, the second type parameter is the parameter of the small injection current region, and the third type parameter is the parameter of the large injection current region.
[0040] Step 4: Establish and modify the device mismatch model, which includes: Beta mismatch model, Vbe mismatch model, first type parameter mismatch function, second type parameter mismatch function and third type parameter mismatch function.
[0041] The first type of parameter mismatch function is a function between the mismatch value of the first type of parameter and the effective area of the emitter.
[0042] The second type of parameter mismatch function is a function between the mismatch value of the second type of parameter and the effective area of the emitter.
[0043] The third type of parameter mismatch function is a function between the mismatch value of the third type of parameter and the effective area of the emitter.
[0044] The first type of parameter mismatch function, the second type of parameter mismatch function, and the third type of parameter mismatch function all have fitting coefficients, which can be modified according to the fitting results in subsequent step five.
[0045] Beta is the current gain, and the formula for the Beta mismatch model is: Delta Beta =2*(Beta1-Beta2) / (Beta1+Beta2); Where Beta1 and Beta2 are two pairs of Beta and Delta of the BJT devices. Beta The mismatch rate between the Beta of the two paired BJT devices is denoted as .
[0046] Vbe is the base-emitter voltage, and the formula for the Vbe mismatch model is: Delta Vbe =Vbe1-Vbe2; Wherein, Vbe1 and Vbe2 are two pairs of Vbe and Delta of the BJT device. Vbe The mismatch rate between the Vbe values of the two paired BJT devices is denoted as Vbe.
[0047] Step 5: Fit the curves of the Beta mismatch model and the Vbe mismatch model; if the fitting result is good, proceed to step 6; if the fitting result is not good, return to step 4.
[0048] Step 6: Verify the device mismatch model.
[0049] A further improvement is that the first type of parameter includes is and bf.
[0050] is is the collector saturation current.
[0051] bf is the forward current gain.
[0052] A further improvement is that the second type of parameter includes ise and ne.
[0053] ise is the reverse saturation current of the emitter junction.
[0054] ne represents the base-emitting system.
[0055] A further improvement is that the third type of parameter includes rb.
[0056] rb is the base region resistance.
[0057] A further improvement is that the formula for the first type of parameter mismatch function includes: f_Mis(is)=1+A*[1 / sqrt(Area_E)].
[0058] f_Mis(bf)=1+B*[1 / sqrt(Area_E)].
[0059] Where f_Mis(is) represents the mismatch function of is, A is the fitting coefficient, and Area_E is the effective emitter area.
[0060] f_Mis(bf) represents the mismatch function of bf, where B is the fitting coefficient.
[0061] A further improvement is that the formula for the second type of parameter mismatch function includes: f_Mis(ise)=1+C*[1 / sqrt(Area_E)].
[0062] f_Mis(ne)=1+D*[1 / sqrt(Area_E)].
[0063] Where f_Mis(ise) represents the mismatch function of ise, and C is the fitting coefficient.
[0064] f_Mis(ne) represents the mismatch function of ne, and D is the fitting coefficient.
[0065] A further improvement is that the formula for the third type of parameter mismatch function includes: f_Mis(rb)=1+E*[1 / sqrt(Area_E)].
[0066] Where f_Mis(rb) represents the mismatch function of rb, and E is the fitting coefficient.
[0067] This invention adds second and third types of parameter mismatch functions corresponding to small and large injection current regions to the first type of parameter mismatch function in the linear current region of the device mismatch model. By fitting the fitting parameters in the second and third types of parameter mismatch functions, the mismatch characteristics of BJT devices in the small and large injection current regions can be well reflected. In addition, the mismatch characteristics in the linear current region are already well-fitted. Therefore, this invention can accurately reflect the mismatch characteristics of BJT devices under different operating currents, thereby improving the modeling accuracy and the applicability of the BJT model. Attached Figure Description
[0068] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 This is an architecture diagram of an existing BJT device mismatch model; Figures 2-7It is the fitting curve of the existing BJT device mismatch model; Figure 8 This is an architectural diagram of the BJT device mismatch model according to an embodiment of the present invention; Figures 9-14 This is the fitting curve of the BJT device mismatch model in the embodiment of the present invention; Figure 15 This is a flowchart of the method for extracting the BJT device mismatch model according to an embodiment of the present invention. Detailed Implementation
[0069] like Figure 8 The diagram shown is an architectural diagram of the BJT device mismatch model according to an embodiment of the present invention. In the BJT device mismatch model according to an embodiment of the present invention, the working region of the BJT device includes: a small injection current region, a linear current region, and a large injection current region; the current in the small injection current region is less than the current in the linear current region, and the current in the large injection current region is greater than the current in the linear current region.
[0070] The device mismatch model 301 includes: Beta mismatch model 302, Vbe mismatch model 303, first type parameter mismatch function, second type parameter mismatch function and third type parameter mismatch function.
[0071] The first type of parameter mismatch function is a function between the mismatch value of the first type of parameter in the linear current region and the effective area of the emitter.
[0072] The second type of parameter mismatch function is a function between the mismatch value of the second type of parameter in the small injection current region and the effective area of the emitter.
[0073] The third type of parameter mismatch function is a function between the mismatch value of the third type of parameter in the large injection current region and the effective area of the emitter.
[0074] In this embodiment of the invention, Beta represents the current gain, and the formula for the Beta mismatch model 302 is as follows: Delta Beta =2*(Beta1-Beta2) / (Beta1+Beta2); Where Beta1 and Beta2 are two pairs of Beta and Delta of the BJT devices. Beta The mismatch rate between the Beta of the two paired BJT devices is denoted as .
[0075] Vbe is the base-emitter voltage, and the formula for the Vbe mismatch model 303 is as follows: Delta Vbe =Vbe1-Vbe2; Wherein, Vbe1 and Vbe2 are two pairs of Vbe and Delta of the BJT device. Vbe The mismatch rate between the Vbe values of the two paired BJT devices is denoted as Vbe.
[0076] The currents in a BJT device include the base current Ib, the collector current Ic, and the emitter current Ie. Beta, or β, is the ratio of Ic to Ib.
[0077] In different injection current regions, the parameters affecting Ic and Ib are different, ultimately resulting in different Beta and Vbe. In this embodiment of the invention, for different injection current regions, the parameters affecting Ic and Ib related to the device mismatch model 301 are selected according to the injection current region and corresponding mismatch functions are set. The parameters are explained as follows: In this embodiment of the invention, the first type of parameter includes is and bf.
[0078] is is the collector saturation current.
[0079] bf is the forward current gain.
[0080] The formula for the first type of parameter mismatch function includes: f_Mis(is)=1+A*[1 / sqrt(Area_E)], Figure 8 The formula for f_Mis(is) is shown in dashed box 304.
[0081] f_Mis(bf)=1+B*[1 / sqrt(Area_E)], Figure 8 The formula for f_Mis(bf) is shown in the dashed box 305.
[0082] Where f_Mis(is) represents the mismatch function of is, A is the fitting coefficient, and Area_E is the effective emitter area.
[0083] f_Mis(bf) represents the mismatch function of bf, where B is the fitting coefficient.
[0084] In this embodiment of the invention, the second type of parameter includes ise and ne.
[0085] ise is the reverse saturation current of the emitter junction.
[0086] ne represents the base-emitting system.
[0087] In the small injection current region, the influence of ise and ne on the current of the BJT device increases. In this embodiment of the invention, by setting the mismatch functions corresponding to ise and ne, the accuracy of the model in the small injection current region can be increased.
[0088] The formula for the second type of parameter mismatch function includes: f_Mis(ise)=1+C*[1 / sqrt(Area_E)]. Figure 8 The formula for f_Mis(ise) is shown in dashed box 306.
[0089] f_Mis(ne)=1+D*[1 / sqrt(Area_E)]. Figure 8 The formula for f_Mis(ne) is shown in the dashed box 307.
[0090] Where f_Mis(ise) represents the mismatch function of ise, and C is the fitting coefficient.
[0091] f_Mis(ne) represents the mismatch function of ne, and D is the fitting coefficient.
[0092] In this embodiment of the invention, the third type of parameter includes rb.
[0093] rb is the base region resistance. In the small injection current region, the influence of ise and ne on the current of the BJT device increases. In this embodiment of the invention, by setting the mismatch functions corresponding to ise and ne, the accuracy of the model in the small injection current region can be increased.
[0094] The formula for the third type of parameter mismatch function includes: f_Mis(rb)=1+E*[1 / sqrt(Area_E)].
[0095] Where f_Mis(rb) represents the mismatch function of rb, and E is the fitting coefficient. Figure 8 The formula for f_Mis(rb) is shown in dashed box 308.
[0096] In this embodiment of the invention, the second type of parameter mismatch function and the third type of parameter mismatch function can respectively achieve accurate fitting in the small injection current region and the large injection current region, thereby improving model accuracy. Figures 9 to 14 The figure shown is the fitting curve of the BJT device mismatch model in an embodiment of the present invention; Figures 9 to 11 Both curves represent the model simulation curves and target curves between the mismatch rates between Beta values, i.e., Sigma (Beta) and 1 / sqrt(AREA). AREA is an abbreviation for Area_E, and 1 / sqrt(AREA) is the reciprocal of the square root of the effective emitter area. Figures 9 to 11 The corresponding temperatures are all 25℃, and the emitter currents (IE) are respectively: Figure 9 In this case, IE = 1.578e-009A, which falls within the small injection current region. Figure 10In this case, IE = 1.000e-006A, which falls within the linear current region. Figure 11 In this case, IE = 1.578e-005A; it belongs to the large injection current region. It can be seen that... Figures 9 to 11 In the simulation, the model curve and the target curve basically coincide. Therefore, the BJT device mismatch model of this invention accurately simulates the mismatch rate of Beta under various operating current conditions.
[0097] Figures 12 to 14 Both are model simulation curves and target curves representing the mismatch rate between Vbe, i.e., Sigma(Vbe) and 1 / sqrt(AREA). Figures 12 to 14 The corresponding temperatures are all 25℃, and the emitter currents (IE) are respectively: Figure 12 In this case, IE = 1.578e-009A, which falls within the small injection current region. Figure 13 In this case, IE = 1.000e-006A, which falls within the linear current region. Figure 14 In this case, IE = 1.578e-005A; it belongs to the large injection current region. It can be seen that... Figures 12 to 14 In the simulation, the model curve and the target curve basically coincide. Therefore, the BJT device mismatch model of this invention accurately simulates the mismatch rate of Vbe under various operating current conditions.
[0098] In this embodiment of the invention, based on the first type of parameter mismatch function corresponding to the linear current region in the device mismatch model 301, second and third type parameter mismatch functions corresponding to the small injection current region and the large injection current region are added. By fitting the fitting parameters in the second and third type parameter mismatch functions, the mismatch characteristics of the BJT device in the small injection current region and the large injection current region can be well reflected. In addition, the mismatch characteristics in the linear current region are already well fitted. Therefore, this embodiment of the invention can accurately reflect the mismatch characteristics of the BJT device under different operating currents, thereby improving the modeling accuracy and the applicability of the BJT model.
[0099] like Figure 15 The diagram shows a flowchart of the method for extracting the BJT device mismatch model according to an embodiment of the present invention. The method for extracting the BJT device mismatch model according to an embodiment of the present invention includes the following steps: Step 1: Fabricate BJT devices on a wafer and perform measurements to obtain measurement data for pairs of BJT devices. Figure 15 In this process, step one, also known as step S101, is to measure the data of the paired BJT devices.
[0100] Step 2: Filter the measurement data.
[0101] Figure 15In the process, step two, also known as step S102, involves establishing a reasonable data filtering system for data filtering.
[0102] Step 3: Calculate the mismatch rate of each parameter of the BJT device; the parameters include: Beta, Vbe, a first type parameter, a second type parameter, and a third type parameter; the operating region of the BJT device includes: a small injection current region, a linear current region, and a large injection current region; the current in the small injection current region is less than the current in the linear current region, and the current in the large injection current region is greater than the current in the linear current region; the first type parameter is the parameter of the linear current region, the second type parameter is the parameter of the small injection current region, and the third type parameter is the parameter of the large injection current region.
[0103] In the method of this embodiment of the invention, the first type of parameter includes is and bf.
[0104] is is the collector saturation current.
[0105] bf is the forward current gain.
[0106] The second type of parameter includes ise and ne.
[0107] ise is the reverse saturation current of the emitter junction.
[0108] ne represents the base-emitting system.
[0109] The third type of parameter includes rb.
[0110] rb is the base region resistance.
[0111] Figure 15 In step three, also known as step S103, the mismatch rate of each parameter is calculated. Each parameter can be calculated based on paired measurement values.
[0112] Step 4: Establish and modify the device mismatch model 301, which includes: Beta mismatch model 302, Vbe mismatch model 303, a first type parameter mismatch function, a second type parameter mismatch function, and a third type parameter mismatch function.
[0113] The first type of parameter mismatch function is a function between the mismatch value of the first type of parameter and the effective area of the emitter.
[0114] The second type of parameter mismatch function is a function between the mismatch value of the second type of parameter and the effective area of the emitter.
[0115] The third type of parameter mismatch function is a function between the mismatch value of the third type of parameter and the effective area of the emitter.
[0116] The first type of parameter mismatch function, the second type of parameter mismatch function, and the third type of parameter mismatch function all have fitting coefficients, which can be modified according to the fitting results in subsequent step five.
[0117] Beta is the current gain, and the formula for the Beta mismatch model 302 is as follows: Delta Beta =2*(Beta1-Beta2) / (Beta1+Beta2); Where Beta1 and Beta2 are two pairs of Beta and Delta of the BJT devices. Beta The mismatch rate between the Beta of the two paired BJT devices is denoted as .
[0118] Vbe is the base-emitter voltage, and the formula for the Vbe mismatch model 303 is as follows: Delta Vbe =Vbe1-Vbe2; Wherein, Vbe1 and Vbe2 are two pairs of Vbe and Delta of the BJT device. Vbe The mismatch rate between the Vbe values of the two paired BJT devices is denoted as Vbe.
[0119] In the method of this embodiment of the invention, the formula for the first type of parameter mismatch function includes: f_Mis(is)=1+A*[1 / sqrt(Area_E)].
[0120] f_Mis(bf)=1+B*[1 / sqrt(Area_E)].
[0121] Where f_Mis(is) represents the mismatch function of is, A is the fitting coefficient, and Area_E is the effective emitter area.
[0122] f_Mis(bf) represents the mismatch function of bf, where B is the fitting coefficient.
[0123] In the method of this embodiment of the invention, the formula for the second type of parameter mismatch function includes: f_Mis(ise)=1+C*[1 / sqrt(Area_E)].
[0124] f_Mis(ne)=1+D*[1 / sqrt(Area_E)].
[0125] Where f_Mis(ise) represents the mismatch function of ise, and C is the fitting coefficient.
[0126] f_Mis(ne) represents the mismatch function of ne, and D is the fitting coefficient.
[0127] In the method of this embodiment of the invention, the formula for the third type of parameter mismatch function includes: f_Mis(rb)=1+E*[1 / sqrt(Area_E)].
[0128] Where f_Mis(rb) represents the mismatch function of rb, and E is the fitting coefficient.
[0129] Figure 15 In this process, step four, also known as step S104, involves establishing and modifying local mismatch models related to different active region environments.
[0130] Step 5: Fit the curves of the Beta mismatch model 302 and the Vbe mismatch model 303; if the fitting result is good, proceed to step 6; if the fitting result is not good, return to step 4.
[0131] Figure 15 In this process, step five, also known as step S105, involves fitting the model curves related to the DC performance of the BJT.
[0132] Step 6: Verify the device mismatch model 301.
[0133] Figure 15 In this process, step six, also known as step S106, is the verification of the BJT mismatch model.
[0134] The present invention has been described in detail above through specific embodiments, but these are not intended to limit the invention. Many modifications and improvements can be made by those skilled in the art without departing from the principles of the invention, and these should also be considered within the scope of protection of the present invention.
Claims
1. A BJT device mismatch model, characterized in that: The operating regions of a BJT device include: a small injection current region, a linear current region, and a large injection current region; the current in the small injection current region is less than the current in the linear current region, and the current in the large injection current region is greater than the current in the linear current region. Device mismatch models include: Beta mismatch model, Vbe mismatch model, first type parameter mismatch function, second type parameter mismatch function, and third type parameter mismatch function; The first type of parameter mismatch function is a function between the mismatch value of the first type of parameter in the linear current region and the effective area of the emitter; The second type of parameter mismatch function is a function between the mismatch value of the second type of parameter in the small injection current region and the effective area of the emitter; The third type of parameter mismatch function is a function between the mismatch value of the third type of parameter in the large injection current region and the effective area of the emitter. Beta is the current gain, and the formula for the Beta mismatch model is: Participate Beta =2*(Beta1-Beta2) / (Beta1+Beta2); Where Beta1 and Beta2 are two pairs of Beta and Delta of the BJT devices. Beta The mismatch rate between the Beta of the two paired BJT devices; Vbe is the base-emitter voltage, and the formula for the Vbe mismatch model is: Delta Vbe =Vbe1-Vbe2; Wherein, Vbe1 and Vbe2 are two pairs of Vbe and Delta of the BJT device. Vbe The mismatch rate between the Vbe values of the two paired BJT devices is denoted as Vbe.
2. The BJT device mismatch model as described in claim 1, characterized in that: The first type of parameter includes is and bf; is is the collector saturation current; bf is the forward current gain.
3. The BJT device mismatch model as described in claim 1, characterized in that: The second type of parameter includes ise and ne; ise is the reverse saturation current of the emitter junction; ne represents the base-emitting system.
4. The BJT device mismatch model as described in claim 1, characterized in that: The third type of parameter includes rb; rb is the base region resistance.
5. The BJT device mismatch model as described in claim 2, characterized in that: The formula for the first type of parameter mismatch function includes: f_Mis(is)=1+A*[1 / sqrt(Area_E)]; f_Mis(bf)=1+B*[1 / sqrt(Area_E)]; Where f_Mis(is) represents the mismatch function of is, A is the fitting coefficient, and Area_E is the effective area of the emitter; f_Mis(bf) represents the mismatch function of bf, where B is the fitting coefficient.
6. The BJT device mismatch model as described in claim 3, characterized in that: The formula for the second type of parameter mismatch function includes: f_Mis(ise)=1+C*[1 / sqrt(Area_E)]; f_Mis(ne)=1+D*[1 / sqrt(Area_E)]; Where f_Mis(ise) represents the mismatch function of ise, and C is the fitting coefficient; f_Mis(ne) represents the mismatch function of ne, and D is the fitting coefficient.
7. The BJT device mismatch model as described in claim 4, characterized in that: The formula for the third type of parameter mismatch function includes: f_Mis(rb)=1+E*[1 / sqrt(Area_E)]; Where f_Mis(rb) represents the mismatch function of rb, and E is the fitting coefficient.
8. A method for extracting a mismatch model of a BJT device, characterized in that, Includes the following steps: Step 1: Fabricate BJT devices on a wafer and perform measurements to obtain measurement data for pairs of the BJT devices; Step 2: Filter the measurement data; Step 3: Calculate the mismatch rate of each parameter of the BJT device; the parameters include: Beta, Vbe, a first type parameter, a second type parameter, and a third type parameter; the operating region of the BJT device includes: a small injection current region, a linear current region, and a large injection current region; the current in the small injection current region is less than the current in the linear current region, and the current in the large injection current region is greater than the current in the linear current region; the first type parameter is the parameter of the linear current region, the second type parameter is the parameter of the small injection current region, and the third type parameter is the parameter of the large injection current region; Step 4: Establish and modify the device mismatch model, which includes: Beta mismatch model, Vbe mismatch model, first type parameter mismatch function, second type parameter mismatch function and third type parameter mismatch function; The first type of parameter mismatch function is a function between the mismatch value of the first type of parameter and the effective area of the emitter; The second type of parameter mismatch function is a function between the mismatch value of the second type of parameter and the effective area of the emitter; The third type of parameter mismatch function is a function between the mismatch value of the third type of parameter and the effective area of the emitter; The first type of parameter mismatch function, the second type of parameter mismatch function, and the third type of parameter mismatch function all have fitting coefficients, which can be modified according to the fitting results in subsequent step five; Beta is the current gain, and the formula for the Beta mismatch model is: Participate Beta =2*(Beta1-Beta2) / (Beta1+Beta2); Where Beta1 and Beta2 are two pairs of Beta and Delta of the BJT devices. Beta The mismatch rate between the Beta of the two paired BJT devices; Vbe is the base-emitter voltage, and the formula for the Vbe mismatch model is: Delta Vbe =Vbe1-Vbe2; Wherein, Vbe1 and Vbe2 are two pairs of Vbe and Delta of the BJT device. Vbe The mismatch rate between the Vbe values of the two paired BJT devices; Step 5: Fit the curves of the Beta mismatch model and the Vbe mismatch model; if the fitting result is good, proceed to step 6; if the fitting result is not good, return to step 4. Step 6: Verify the device mismatch model.
9. The method for extracting the BJT device mismatch model as described in claim 8, characterized in that: The first type of parameter includes is and bf; is is the collector saturation current; bf is the forward current gain.
10. The method for extracting the BJT device mismatch model as described in claim 8, characterized in that: The second type of parameter includes ise and ne; ise is the reverse saturation current of the emitter junction; ne represents the base-emitting system.
11. The method for extracting the BJT device mismatch model as described in claim 8, characterized in that: The third type of parameter includes rb; rb is the base region resistance.
12. The method for extracting the BJT device mismatch model as described in claim 9, characterized in that: The formula for the first type of parameter mismatch function includes: f_Mis(is)=1+A*[1 / sqrt(Area_E)]; f_Mis(bf)=1+B*[1 / sqrt(Area_E)]; Where f_Mis(is) represents the mismatch function of is, A is the fitting coefficient, and Area_E is the effective area of the emitter; f_Mis(bf) represents the mismatch function of bf, where B is the fitting coefficient.
13. The method for extracting the BJT device mismatch model as described in claim 10, characterized in that: The formula for the second type of parameter mismatch function includes: f_Mis(ise)=1+C*[1 / sqrt(Area_E)]; f_Mis(ne)=1+D*[1 / sqrt(Area_E)]; Where f_Mis(ise) represents the mismatch function of ise, and C is the fitting coefficient; f_Mis(ne) represents the mismatch function of ne, and D is the fitting coefficient.
14. The method for extracting the BJT device mismatch model as described in claim 11, characterized in that: The formula for the third type of parameter mismatch function includes: f_Mis(rb)=1+E*[1 / sqrt(Area_E)]; Where f_Mis(rb) represents the mismatch function of rb, and E is the fitting coefficient.