1
GATE ECE 2012
+2
-0.6
In the three dimensional view of a silicon n-channel MOS transistor shown below, $$\delta = 20$$ nm. The transistor is of width 1 $$\mu m$$. The depletion width formed at every p-n junction is 10 nm. The relative permittivities of Si and SiO2, respectively, are 11.7 and 3.9, and $${\varepsilon _0}$$ = 8.9 $$\times {10^{ - 12}}$$ F/m.

The source-body junction capacitance is approximately

A
2 fF
B
7 fF
C
2 pF
D
7 pF
2
GATE ECE 2012
+2
-0.6
In the CMOS circuit shown, electron and hole mobilities are equal, and M1 and M2 are equally sized. The device M1 is in the linear region if
A
V in < 1.875 V
B
1.875 V < V in < 3.125 V
C
V in > 3.125 V
D
0 < V in < 5 V
3
GATE ECE 2009
+2
-0.6
Consider the CMOS circuit shown, where the gate voltage of the n-MOSFET is increased from zero, while the gate voltage of the p-MOSFET is kept constant at 3 V. Assume that, for both transistors, the magnitude of the threshold voltage is 1 V and the product of the transconductance parameter and the $$\left(\frac WL\right)$$ ratio, i.e. the quantity $$\mu C_{ox}\left(\frac WL\right)$$ , is 1 mAV-2.
For small increase in VG beyond 1 V, which of the following gives the correct description of the region of operation of each MOSFET?
A
Both the MOSFETs are in saturation region
B
Both the MOSFETs are in triode region
C
n-MOSFET is triode and p-MOSFET is in saturation region
D
n-MOSFET is in saturation and p-MOSFET is in triode region
4
GATE ECE 2009
+2
-0.6
Consider the CMOS circuit shown, where the gate voltage of the n-MOSFET is increased from zero, while the gate voltage of the p-MOSFET is kept constant at 3 V. Assume that, for both transistors, the magnitude of the threshold voltage is 1 V and the product of the transconductance parameter and the $$\left(\frac WL\right)$$ ratio, i.e. the quantity $$\mu C_{ox}\left(\frac WL\right)$$ , is 1 mAV-2.
Estimate the output voltage V0 for VG =1.5 V. [Hints: Use the appropriate current-voltage equation for each MOSFET, based on the answer]
A
$$\left(4-\frac1{\sqrt2}\right)V$$
B
$$\left(4+\frac1{\sqrt2}\right)V$$
C
$$\left(4-\frac{\sqrt3}2\right)V$$
D
$$\left(4+\frac{\sqrt3}2\right)V$$
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