As a general feature, the electric field of a localized electric charge distribution diminishes as the distance from the distribution increases;there are exceptions to this feature. For instance, the electric field of...As a general feature, the electric field of a localized electric charge distribution diminishes as the distance from the distribution increases;there are exceptions to this feature. For instance, the electric field of a charged ring (being a localized charge distribution) along its symmetry axis perpendicular to the ring through its center rather than as expected being a diminishing field encounters a local maximum bump. It is the objective of this research-oriented study to analyze the impact of this bump on the characteristics of a massive point-like charged particle oscillating along the symmetry axis. Two scenarios with and without gravity along the symmetry axis are considered. In addition to standard kinematic diagrams, various phase diagrams conducive to a better understanding are constructed. Applying Computer Algebra System (CAS), [1] [2] most calculations are carried out symbolically. Finally, by assigning a set of reasonable numeric parameters to the symbolic quantities various 3D animations are crafted. All the CAS codes are included.展开更多
This paper presents a new method to increase the speed of the separated absorption, grading, charge, and multiplication avalanche photodiode （SAGCM-APD）. This improvement is obtained by adding a new thin charge laye...This paper presents a new method to increase the speed of the separated absorption, grading, charge, and multiplication avalanche photodiode （SAGCM-APD）. This improvement is obtained by adding a new thin charge layer between absorption and grading layers, with assuming the non-uniform electric field in different regions of the structure. In addition, a circuit model of the proposed structure is extracted, using carrier rate equations. Also, to achieve the optimum structure, it is tried to have trade-offs among thickness of the layers and have proper tuning of physical parameters. Eventually, frequency and transient response are investigated and it is shown that, in comparison with the previous conventional structure, significant improvements in gain-bandwidth product, speed and also in breakdown voltage are attained.展开更多
The theory of direct magnetoelectric(ME)effect in a bilayer of ferromagnetic and piezoelectric is developed taking into account nonuniform distribution of electrical field on a piezoelectric layer thickness.The simult...The theory of direct magnetoelectric(ME)effect in a bilayer of ferromagnetic and piezoelectric is developed taking into account nonuniform distribution of electrical field on a piezoelectric layer thickness.The simultaneous solution of the motion equations for piezoelectric and ferromagnetic mediums allowed to numerically and analytically calculate the dependence of natural mechanical oscillation on structure parameters and to determine the dependence of ME effect coefficient on frequency of the variable magnetic field.展开更多
This paper presents a circuit model for thin avalanche photodiodes （APDs）. In this model, the nonuniformity of the electric filed in the multiplication region is modeled using a stepwise method. The model also tries...This paper presents a circuit model for thin avalanche photodiodes （APDs）. In this model, the nonuniformity of the electric filed in the multiplication region is modeled using a stepwise method. The model also tries to take the effects of carrier＇s position dependent properties, like carder＇s dead length and the history of carder＇s previous ionization into account by developing an effective electric field in the multiplication region. The output photocurrent and multiplication gain obtained from the proposed model for different lengths of the multi- plication region achieve a good agreement in comparison with available experimental data. In addition, calculated excess noise factor reveals the model ability for noise and sensitivity analysis.展开更多
文摘As a general feature, the electric field of a localized electric charge distribution diminishes as the distance from the distribution increases;there are exceptions to this feature. For instance, the electric field of a charged ring (being a localized charge distribution) along its symmetry axis perpendicular to the ring through its center rather than as expected being a diminishing field encounters a local maximum bump. It is the objective of this research-oriented study to analyze the impact of this bump on the characteristics of a massive point-like charged particle oscillating along the symmetry axis. Two scenarios with and without gravity along the symmetry axis are considered. In addition to standard kinematic diagrams, various phase diagrams conducive to a better understanding are constructed. Applying Computer Algebra System (CAS), [1] [2] most calculations are carried out symbolically. Finally, by assigning a set of reasonable numeric parameters to the symbolic quantities various 3D animations are crafted. All the CAS codes are included.
文摘This paper presents a new method to increase the speed of the separated absorption, grading, charge, and multiplication avalanche photodiode （SAGCM-APD）. This improvement is obtained by adding a new thin charge layer between absorption and grading layers, with assuming the non-uniform electric field in different regions of the structure. In addition, a circuit model of the proposed structure is extracted, using carrier rate equations. Also, to achieve the optimum structure, it is tried to have trade-offs among thickness of the layers and have proper tuning of physical parameters. Eventually, frequency and transient response are investigated and it is shown that, in comparison with the previous conventional structure, significant improvements in gain-bandwidth product, speed and also in breakdown voltage are attained.
文摘The theory of direct magnetoelectric(ME)effect in a bilayer of ferromagnetic and piezoelectric is developed taking into account nonuniform distribution of electrical field on a piezoelectric layer thickness.The simultaneous solution of the motion equations for piezoelectric and ferromagnetic mediums allowed to numerically and analytically calculate the dependence of natural mechanical oscillation on structure parameters and to determine the dependence of ME effect coefficient on frequency of the variable magnetic field.
文摘This paper presents a circuit model for thin avalanche photodiodes （APDs）. In this model, the nonuniformity of the electric filed in the multiplication region is modeled using a stepwise method. The model also tries to take the effects of carrier＇s position dependent properties, like carder＇s dead length and the history of carder＇s previous ionization into account by developing an effective electric field in the multiplication region. The output photocurrent and multiplication gain obtained from the proposed model for different lengths of the multi- plication region achieve a good agreement in comparison with available experimental data. In addition, calculated excess noise factor reveals the model ability for noise and sensitivity analysis.
