GATE EC Analog Circuits questions

An

\text{NMOS}

transistor operating in the linear region has

I_{D S}

of

5 \mu \mathrm{A}

at

V_{D S}

of

0.1 \mathrm{~V}

. Keeping

V_{G S}

constant, the

V_{D S}

is increased to

1.5 \mathrm{~V}

. Given that

\mu_{n} C_{o x} \frac{W}{L}=50 \mu \mathrm{A} / \mathrm{V}^{2}

, the transconductance at the new operating point (in …

In the circuit shown below,

\text{V}_1

and

\text{V}_2

are bias voltages. Based on input and output impedances, the circuit behaves as a

The

\frac{V_{\text{OUT }}}{V_{\text{IN }}}

of the circuit shown below is

In the circuit shown below,

D_1

and

D_2

are silicon diodes with cut-in voltage of

0.7 \mathrm{~V}

.

\mathrm{V}_{\mathrm{IN}}

and

\mathrm{V}_{\mathrm{OUT}}

are input and output voltages in volts. The transfer characteristic is

Consider the

\text{CMOS}

circuit shown in the figure (substrates are connected to their respective sources). The gate width

(W)

to gate length

(L)

ratios

\left( \frac{W}{L} \right)

of the transistors are as shown. Both the transistors have the same gate oxide capacitance per unit area. For the

p\text{MOSFET},

the threshold voltage is …

The ideal long channel

n\text{MOSFET}

and

p\text{MOSFET}

devices shown in the circuits have threshold voltages of

1 \; \text{V}

and

– 1 \; \text{V},

respectively. The

\text{MOSFET}

substrates are connected to their respective sources. Ignore leakage currents and assume that the capacitors are initially discharged. For the applied voltages …

An ideal

\text{OPAMP}

circuit with a sinusoidal input is shown in the figure. The

3 \; \text{dB}

frequency is the frequency at which the magnitude of the voltage gain decreases by

3 \; \text{dB}

from the maximum value. Which of the options is/are correct?

An ideal

\text{MOS}

capacitor (p-type semiconductor) is shown in the figure. The

\text{MOS}

capacitor is under strong inversion with

V_{G} = 2 \; \text{V}.

The corresponding inversion charge density

(Q_{IN})

is

2.2 \; \mu \text{C /cm}^{2}.

Assume oxide capacitance per unit area as

C_{\text{ox}} = 1.7 \; \mu \text{F/cm}^{2}.

For …

Consider an ideal long channel

n \text{MOSFET}

(enhancement-mode) with gate length

10 \; \mu \text{m}

and width

100 \; \mu \text{m}.

The product of electron mobility

(\mu_{n})

and oxide capacitance per unit area

(C_{\text{ox}})

is

\mu_{n} C_{\text{ox}} = 1 \; \text{mA/V}^{2}.

The threshold voltage of the transistor is …

For the following circuit with an ideal

\text{OPAMP},

the difference between the maximum and the minimum values of the capacitor voltage

(V_{c})

is ____________.

A circuit with an ideal

\text{OPAMP}

is shown. The Bode plot for the magnitude

\text{(in dB)}

of the gain transfer function

(A_{V} (j \omega) = V_{\text{out}} (j \omega) / V_{\text{in}} (j \omega))

of the circuuit is also provided (here,

\omega

is the angular frequency in

\text{rad/s}.

) The values of

R

and

C

are ________________.

A circuit and the characteristics of the diode

\text{(D)}

in it are shown. The ratio of the minimum to the maximum small signal voltage gain

\frac{\partial V_{\text{out}}}{\partial V_{\text{in}}}

is ____________ (rounded off to two decimal places).

Consider the circuit shown with an ideal

\text{OPAMP}.

The output voltage

V_{0}

is ____________

V

(rounded off to two decimal places).

Consider the circuit shown with an ideal long channel

n \text{MOSFET}

(enhancement-mode, substrate is connected to the source). The transistor is appropriately biased in the saturation region with

V_{GG}

and

V_{DD}

such that it acts as a linear amplifier.

v_{i}

is the small-signal ac input voltage.

v_{A}

and

v_{B}

represent the …

In the circuit shown in the figure, the transistors

M_{1}

and

M_{2}

are operating in saturation. The channel length modulation coefficients of both the transistors are non-zero. The transconductance of the

\text{MOSFETs}

M_{1}

and

M_{2}

are

g_{m1}

and

g_{m2}

, respectively, and the internal resistance of the …

For the circuit with an ideal

\text{OPAMP}

shown in the figure.

V_{\text{REF}}

is fixed. If

V_{\text{OUT}}=1

volt for

V_{\text{IN}}-0.1

volt and

V_{\text{OUT}}=6

volt for

V_{\text{IN}}=1

volt, where

V_{\text{OUT}}

is measured across

R_{L}

connected at the output of this

\text{OPAMP}

, the value of

R_{F}/R_{\text{IN}}

is

Consider the circuit with an ideal

\text{OPAMP}

shown in the figure. Assuming

\left | V_{\text{IN}} \right |\ll \left | V_{\text{CC}} \right |

and

\left | V_{\text{REF}} \right |\ll \left | V_{\text{CC}} \right |

, the condition at which

V_{\text{OUT}}

equals to zero is

For an

n

-channel silicon

\text{MOSFET}

with

10\:nm

gate oxide thickness, the substrate sensitivity

\left ( \partial V_{T}/\partial \left | V_{BS} \right | \right )

is found to be

50\:mV/V

at a substrate voltage

\left | V_{BS} \right |=2V

, where

V_{T}

is the threshold voltage of the

\text{MOSFET}

. Assume that, …

An asymmetrical periodic pulse train

v_{in}

of

10\:V

amplitude with on-time

T_{\text{ON}}=1\:ms

and off-time

T_{\text{OFF}}=1\:\mu s

is applied to the circuit shown in the figure. The diode

D_{1}

is ideal. The difference between the maximum voltage and minimum voltage of the output waveform

v_{o}

(in integer) is ______________

V

.

For the transistor

M_{1}

in the circuit shown in the figure,

\mu_{n} C_{\text{ox}} = 100\:\mu A/V^{2}

and

(W/L)=10

, where

\mu_{n}

is the mobility of electron,

C_{\text{ox}}

is the oxide capacitance per unit area ,

W

is the width and

L

is the length. The channel length modulation coefficient is ignored. If the gate-to-source …