Question

the Ebers-Moll VT = kB T/e. (c) Use your result from part (b) to find the resistance Rg necessary to generate 7.5μΑ of current with 20μΑ of programming current. (programming 6. FET I-V Curves. [10 pts.] Consider the family of I- V curves for a field effect transistor (FET) shown below. (a) Are the curves shown for a JFET or or an en- hancement mode MOSFET? Explain briefly how you know. (b) Table values for the given gain-source volt- ages Vos, the corresponding drain current in the saturation region Ip, and vp. Plot Ip as a func- tion of Vos using Mathematica, Excel, or a simi- lar program. Label your axes, including units (c) Separately plot vIp as a function of Vos. La- latmA) 5 bel your axes. Find the slope and y-intercept of your graph to determine the threshold or pinch- off voltage Vo, the constant K in the expression for the drain current, i.e., ID = K (VGS-Vo)2, and the drain source current with the gate shorted to the source Ipss. Do not forget to include units for V0, K, and IDSS. (d) Using your above results, what is the transconductance gain gm as a function of Vas? 10 -0.5 4 1.5 2.0 2.5 0 2 4 6 8 10 12 14 16 Vds(V)

Answer 1

"a) All the V_GS values are lessthanorequalto 0, i.e. Gate voltage is lessthanorequalto 0. Therefore the curves are for an n-channel JFET. For an n-channel Enhancement MOSFET, through the shape of the curves are similar, but V_GS value must be lessthanorequalto 0 so that the MOSFET is turned on and conduction current. b) Table I shows the V_GS values and corresponding saturation drain current I_D. MATLAB code for plotting I_D as function of V_GS: Vgs = [0 .5 -1 -1.5 -2 -2.5]: Id = [9 6.2 4 2.2 1 0.2]: figure: plot (Vgs, Id, 'k'): x Label ('V_{GS} (V) >^') v: y Label ('I_D (mA) >^'): title ('I_D vs V_{GS} curve of n-channel JFET^'): MATLAB code: root_Id = squareroot (Id): figure: plot (Vgs, root_Id, 'k'): grid on: x Label ('V_{GS} (V) >^""): y Label ('I_D^{1/2} (mA^{1/2}) >^'): title ('I_D^{1/2} vs V_{GS} vs curve of "

Table I shows the V_GS values and corresponding saturation drain current I_D.