1. For the circuit shown in the following figure, transistors M1 and
M2 are identical nMOS transistors. Assume that M2 is in
saturation and the output is unloaded . The current Ix is related
to I bias as
2. The measured transconductance gm of an NMOS transistor
operating in the linear region is plotted against the gate voltage
VG at constant drain voltage VD. Which of the following figures
represents the expected dependence of gm on VG ?
3. Two identical NMOS transistors M1 and M2 are connected as
shown below. Vbias is chosen so that both transistors are in
saturation. The equivalent gm of the pair is defined to be
(dIout / dVi ) at constant Vout. The equivalent gm of the pair is
4. Silicon is doped with boron to a concentration of 4 x 1017
atoms /cm3. Assuming the intrinsic carrier concentration of
silicon to be 1.5 x 1010 / cm3 and the value of KT/q to be 25mV
at 300oK. compared to undoped silicon, the Fermi level of
5. The cross section of a JFET is shown in the following figure.
Let VG be -2 volts and let Vp be the initial pinch off voltage.
If the width W is doubled (with other geometric parameters
and doping levels remaining the same), then the ratio between
the mutual transconductance of the initial and the modified
6. Consider the following assertions.
S1 : For Zener effect to occur, a very abrupt junction is
S2 : For quantum tunneling to occur, a very narrow
energy barrier is required .
Which of the following is correct ?
(A) Only S2 is true
(B) S1 and S2 are both true but S2 is not a reason for S1
(C) S1 and S2 are both true but S2 is a reason for S1
(D) Both S1 and S2 are false