Qucs simulation sharp transitions trouble

To complete the model, a general expression for the thermal noise valid in all regions of operation is derived. All these transadmittances have the same characteristic time constant which depends on the bias condition in a continuous manner. This small-signal model is then extended to higher frequencies by replacing the transconductances by first order transadmittances obtained from a non-quasi-static calculation. The transconductances and the intrinsic capacitances are modelled in moderate inversion using the same interpolation function and without any additional parameters. A quasi-static small-signal model including the transconductances and the intrinsic capacitances is obtained from an accurate evaluation of the total charges stored on the gate and in the channel. The current in the moderate inversion region is then modelled by using an appropriate interpolation function resulting in a continuous expression valid from weak to strong inversion. This function is exponential in weak inversion and quadratic in strong inversion. Each of these is proportional to a function ofV Using the charge sheet model with the assumption of constant doping in the channel, the drain currentIД is derived and expressed as the difference between a forward componentI The various modes of operation of the transistor are then presented in terms of voltagesV

It depends only on the gate voltage and can be interpreted as the equivalent effect of the gate voltage referred to the channel. The pinch-off voltageVД¬h such that the inversion charge is zero for a given gate voltage. It is shown that the inversion chargeQД¬h is the channel voltage, defined as the difference between the quasi-Fermi potentials of the carriers. The model exploits the inherent symmetry of the device by referring all the voltages to the local substrate. The same approach is used to derive all the equations of the model: the weak and strong inversion asymptotes are first derived, then the variables of interest are normalized and linked using an appropriate interpolation function. All the large- and small-signal variables, namely the currents, the transconductances, the intrinsic capacitances, the non-quasi-static transadmittances and the thermal noise are continuous in all regions of operation, including weak inversion, moderate inversion, strong inversion, conduction and saturation. Monte Carlo simulations composition-related structural transition conformation hydrophobicity intrinsically disordered protein.A fully analytical MOS transistor model dedicated to the design and analysis of low-voltage, low-current analog circuits is presented. Thus, we achieve a better understanding on composition-structure relation of the natural proteins and the underlying physics. Our observations imply that the hydrophobicity contributes essentially to such composition-related transitions. Furthermore, the contributions of various interactions to the structural variation of peptides are analyzed based on the contact statistics and the charge-pattern dependence of the gyration radii of the peptides. These results outline the basic physical reasons for the compositional distinction between the intrinsically disordered proteins and the folded proteins. These thresholds of hydrophobicity and net charge are quantitatively consistent with the border line observed from the study of bioinformatics. For several cases, when the mean hydrophobicity is larger than a certain threshold, the transition temperature is higher than the room temperature, and vise versa. The corresponding transition temperature is found to be dependent on the contents of the hydrophobic and charged residues. Based on simulations using all-atom model and replica-exchange Monte Carlo method, a coil-globule transition is observed for each peptide.

What induces such a composition-related structural transition? How do various kinds of interactions work in such processes? In this work, we investigate these problems based on a survey on peptides randomly composed of charged residues (including glutamic acids and lysines) and the residues with different hydrophobicity, such as alanines, glycines, or phenylalanines. Previous studies based on bioinformatics showed that there is a sharp distinction of structural features and residue composition between the intrinsically disordered proteins and the folded proteins.

Qucs simulation sharp transitions trouble