AN ANALYTICAL MOS-TRANSISTOR MODEL VALID IN ALL REGIONS OF OPERATION AND DEDICATED TO LOW-VOLTAGE AND LOW-CURRENT APPLICATIONS
AN ANALYTICAL MOS-TRANSISTOR MODEL VALID IN ALL REGIONS OF OPERATION AND DEDICATED TO LOW-VOLTAGE AND LOW-CURRENT APPLICATIONS
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DOI：
10.1007/bf01239381
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发表时间：
1995-07-01
影响因子：
1.4
通讯作者：
VITTOZ, EA
中科院分区：
文献类型：
--
作者：
ENZ, CC;KRUMMENACHER, F;VITTOZ, EA
本文提出了一种用于低压、小电流模拟电路设计和分析的MOS晶体管模型。所有的大信号和小信号变量，即电流，跨导，本征电容，非准静态跨导纳和热噪声是连续的，在所有的操作区域，包括弱反转，中度反转，强反转，传导和饱和。使用相同的方法来推导模型的所有方程：首先推导弱和强反演渐近线，然后使用适当的插值函数将感兴趣的变量归一化并链接。该模型利用了固有的对称性的设备，指所有的电压到本地基板。结果表明，反转电荷Q ′（inv）由电压差V-p - V-ch控制，其中V-ch是沟道电压，定义为载流子准费米势之差。夹断电压V-P被定义为V-ch的特定值，使得对于给定的栅极电压，反转电荷为零。它只取决于栅极电压，可以解释为栅极电压对沟道的等效影响。晶体管的各种工作模式然后以电压V-P - V-S和V-P - V-D表示。利用电荷片模型，在沟道中恒定掺杂的假设下，导出了漏极电流I-D，并将其表示为正向分量I-F和反向分量I-R之差。通过特定的电流I-S，这些中的每一个与V-P-V-S的函数成比例，相应地与V-P - V-D成比例。该函数在弱反演中是指数函数，在强反演中是二次函数。然后，通过使用适当的插值函数，在一个连续的表达有效的弱到强的反转的电流在中度反转区域建模。一个准静态的小信号模型，包括跨导和本征电容获得从存储在栅极和沟道中的总电荷的准确评估。跨导和本征电容的建模在温和的反转使用相同的插值函数，没有任何额外的参数。这个小信号模型，然后扩展到更高的频率，通过取代的跨导从非准静态计算获得的一阶跨导纳。所有这些跨导纳具有相同的特征时间常数，其以连续的方式取决于偏置条件。为了完成该模型，推导出在所有操作区域中有效的热噪声的一般表达式。该模型已成功地在几个计算机模拟程序中实现，并且只有9个物理参数，3个微调拟合系数和2个附加温度参数。
A fully analytical MOS transistor model dedicated to the design and analysis of low-voltage, low-current analog circuits is presented. 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. 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. The model exploits the inherent symmetry of the device by referring all the voltages to the local substrate. It is shown that the inversion charge Q'(inv) is controlled by the voltage difference V-p - V-ch, where V-ch is the channel voltage, defined as the difference between the quasi-Fermi potentials of the carriers. The pinch-off voltage V-P is defined as the particular value of V-ch such that the inversion charge is zero for a given gate voltage. It depends only on the gate voltage and can be interpreted as the equivalent effect of the gate voltage referred to the channel. The various modes of operation of the transistor are then presented in terms of voltages V-P - V-S and V-P - V-D. Using the charge sheet model with the assumption of constant doping in the channel, the drain current I-D is derived and expressed as the difference between a forward component I-F and a reverse component I-R. Each of these is proportional to a function of V-P - V-S, respectively V-P - V-D, through a specific current I-S. This function is exponential in weak inversion and quadratic in strong inversion. 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. 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 transconductances and the intrinsic capacitances are modelled in moderate inversion using the same interpolation function and without any additional parameters. 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. All these transadmittances have the same characteristic time constant which depends on the bias condition in a continuous manner. To complete the model, a general expression for the thermal noise valid in all regions of operation is derived. This model has been successfully implemented in several computer simulation programs and has only 9 physical parameters, 3 fine tuning fitting coefficients and 2 additional temperature parameters.