Mosfet I-V Equation

The channel current is: I = V (q n S ?W) /L = Vq ?W (c i /q) ×(V GS –V T)/L MOSFET I-V characteristics: general consideration The current through the channel is V I R = where V is the DRAIN – SOURCE voltage Here, we are assuming that V << V T (we will see why, later on) The channel resistance, R (W is the device width): s LL R qn aW qn W?? ==-+ G Semiconductor, Linear I-V characteristics of a MOSFET with V T = 1 V. (m n = 300 cm 2 /V-s, W/L = 5 and t ox = 20 nm). The figure illustrates the behavior of the device in the linear regime: While there is no drain current if the gate voltage is less than the threshold voltage, the current increases with gate voltage once it is larger than the threshold voltage.Hence it is called as depletion mode MOSFET . Working of N-Channel MOSFET (Enhancement Mode) The same MOSFET can be worked in enhancement mode, if we can change the polarities of the voltage V GG. So, let us consider the MOSFET with gate source voltage V.MOSFET transistor I-V characteristics iD K 2()vGS–Vt vDS vDS 2 = []– iD vGS vDS--+ + iD Kv()GS–Vt 2 = []()1 + ?vDS K W 2L = -----Kn Kn Coxµ n i = Linear region: D = K[]2()vGS–Vt vDS vDS sat = vGS–Vt vDS«vGS–Vt Triode region: vDS