1
GATE ECE 2021
MCQ (Single Correct Answer)
+2
-0.67

For an $n$-channel silicon MOSFET with 10 nm gate oxide thickness, the substrate sensitivity ( $\partial V_T / \partial\left|V_{B S}\right|$ ) is found to be $50 \mathrm{mV} / \mathrm{V}$ at a substrate voltage $\left|V_{B S}\right|=2 \mathrm{~V}$, where $V_T$ is the threshold voltage of the MOSFET. Assume that, $\left|V_{B S}\right| \gg 2 \phi_B$, where $q \phi_B$ is the separation between the Femi energy level $E_F$ and the intrinsic level $E_i$ in the bulk. Parameters given are

Electron charge $(q)=1.6 \times 10^{-9} \mathrm{C}$

Vacuum permittivity $\left(\varepsilon_o\right)=8.85 \times 10^{-12} \mathrm{~F} / \mathrm{m}$

Relative permittivity of silicon $\left(\varepsilon_{S i}\right)=12$

Relative permittivity of oxide $\left(\varepsilon_{o x}\right)=4$

The doping concentration of the substrate is

A

$2.37 \times 10^{15} \mathrm{~cm}^{-3}$

B

$4.37 \times 10^{15} \mathrm{~cm}^{-3}$

C

$9.37 \times 10^{15} \mathrm{~cm}^{-3}$

D

$7.37 \times 10^{15} \mathrm{~cm}^{-3}$

2
GATE ECE 2020
MCQ (Single Correct Answer)
+2
-0.67

Using the incremental low frequency small - signal model of the MOS device, the Norton equivalent resistance of the following circuit is

GATE ECE 2020 Analog Circuits - FET and MOSFET Question 3 English
A

$r_{d s}+R$

B

$\frac{r_{d s}+R}{1+g_m r_{d s}}$

C

$r_{d s}+R+g_m r_{d s} R$

D

$r_{d s}+\frac{1}{g_m}+R$

3
GATE ECE 2020
MCQ (Single Correct Answer)
+2
-0.67

An enhancement MOSFET of threshold voltage 3 V is being used in the sample and hold circuit given below. Assume that the substrate of the MOS device is connected to -10 V . If the input voltage $v_1$ liesbetween $\pm 10 \mathrm{~V}$, the minimum and the maximum value of $v_G$ required for proper sampling and holding respectively, are

GATE ECE 2020 Analog Circuits - FET and MOSFET Question 2 English

A

10 V and -10 V

B

13 V and -7 V

C

10 V and -13 V

D

3 V and -3 V

4
GATE ECE 2013
MCQ (Single Correct Answer)
+2
-0.6
The ac schematic of an NMOS common-source stage is shown in the figure below, where part of the biasing circuits has been omitted for simplicity. For the n -channel MOSFET M, the transconductance gm = 1 mA/V, and body effect and channel length modulation effect are to be neglected. The lower cutoff frequency in Hz of the circuit is approximately at GATE ECE 2013 Analog Circuits - FET and MOSFET Question 21 English
A
8
B
32
C
50
D
200

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