The NMOS component is a simple model of an n-channel metal-oxide semiconductor FET. The model does not contain capacitances. A large drain-source resistance, $R_{\mathrm{DS}}$, is included to avoid numerical difficulties.

An optional heat port may be connected to a heatsink, however, the electrical parameters are not temperature dependent.

On-Resistance

When used as a switch, the on-resistance of the transistor is approximately $R_{\mathrm{on}}\approx \frac{1}{\mathrm{\beta }\left(W/L\right)\left(v_{\mathrm{GS}}-V_T\right)}$ where $v_{\mathrm{GS}}$ is the applied gate-to-source voltage. Because the default parameter values yield a relatively high on-resistance. the product $\mathrm{\beta }\left(W/L\right)$ should be increased by several orders of magnitude when using this device in a high-power application.

$i_B\=i_G\=0$

$i_{\mathrm{D}}\&equals;-i_S\&equals;\{\begin{array}{cc}-i_{\mathrm{D}}& v_{\mathrm{D}}<v_S\\ i_{\mathrm{D}}& \mathrm{otherwise}\end{array}$

$i_{\mathrm{D}}\&equals;u_{\mathrm{DS}}{g}_{\mathrm{DS}}\&plus;\{\begin{array}{cc}0& u_{\mathrm{GST}}\le 0\\ v{u}_{\mathrm{DS}}\left(u_{\mathrm{GST}}-\frac{1}{2}{u}_{\mathrm{DS}}\right)& u_{\mathrm{DS}}<u_{\mathrm{GST}}\\ \frac{1}{2}v{u}_{\mathrm{GST}}^2& \mathrm{otherwise}\end{array}$

$g_{\mathrm{DS}}\&equals;\{\begin{array}{cc}\frac{1}{R_{\mathrm{small}}}& -R_{\mathrm{small}}<R_{\mathrm{DS}}<R_{\mathrm{small}}\\ \frac{1}{R_{\mathrm{DS}}}& \mathrm{otherwise}\end{array}$

$u_{\mathrm{BS}}\&equals;\{\begin{array}{cc}0& u_S<v_B\\ v_B-u_S& \mathrm{otherwise}\end{array}$

$u_{\mathrm{D}}\&equals;\{\begin{array}{cc}{v}_S& v_{\mathrm{D}}<v_S\\ v_{\mathrm{D}}& \mathrm{otherwise}\end{array}$

$u_{\mathrm{DS}}\&equals;u_{\mathrm{D}}-u_S$

$u_{\mathrm{GST}}\&equals;\left(K_2{u}_{\mathrm{BS}}\&plus;v_G-V_T-u_S\right)K_5$

$u_S\&equals;\{\begin{array}{cc}{v}_{\mathrm{D}}& v_{\mathrm{D}}<v_S\\ v_S& \mathrm{otherwise}\end{array}$

$v\&equals;\mathrm{\beta }\frac{W\&plus;\mathrm{dW}}{L\&plus;\mathrm{dL}}$

$T_{\mathrm{int}}\&equals;\{\begin{array}{cc}{T}_{\mathrm{heatPort}}& \mathrm{Use\; Heat\; Port}\\ T& \mathrm{otherwise}\end{array}$

$\mathrm{LossPower}\&equals;i_{\mathrm{D}}\left(v_{\mathrm{D}}-v_S\right)$

The component described in this topic is from the Modelica Standard Library. To view the original documentation, which includes author and copyright information, click here.