GATE EC question library

The neutral base width of a bipolar transistor, biased in the active region, is

0.5 \; \mu \mathrm{m}

. The maximum electron concentration and the diffusion constant in the base are

10^{14} / \mathrm{cm}^{3}

and

\mathrm{D}_{n}

=25 \mathrm{~cm}^{2} / \mathrm{sec}

respectively. Assuming negligible recombination in the base, the collector current …

Assuming that the

\beta

of the transistor is extremely large and

\text{V}_{\text{B E}}=0.7 \mathrm{~V}, \text{I}_{\text{C}}

and

\text{V}_{\text{CE}}

in the circuit shown in the figure are

A bipolar transistor is operating in the active region with a collector current of

1 \mathrm{~mA}

. Assuming that the

\beta

of the transistor is

100

and the thermal voltage

\left(\mathrm{V}_{\mathrm{T}}\right)

is

25 \; \mathrm{mV}

, the transconductance

\left(g_{m}\right)

and the input resistance

\left(r_{n}\right)

of the transistor …

The value of

\mathrm{C}

required for sinusoidal oscillations of frequency

1 \; \mathrm{kHz}

in the circuit of given figure is

In the

\text{op-amp}

circuit given in the figure, the load current

i_{\text{L}}

is

In the voltage regulator shown in the given figure, the load current can vary from

100 \mathrm{~mA}

to

500 \mathrm{~mA}

. Assuming that the Zener diode is ideal (i.e., the Zener knee current is negligibly small and Zener resistance is zero in the breakdown region), the value of

R

is

In a full-wave rectifier using two ideal diodes,

V_{d i}

and

V_{i d}

are the

d c

and peak values of the voltage respectively across a resistive load. If PIV is the peak inverse voltage of the diode, then the appropriate relationships for this rectifier are

The minimum number of

2

-to-

1

multiplexers required to realize a

4

-to

1

mulitiplexer is

The Boolean expression

\text{AC + B} \overline{\text{C}}

is equivalent to

11001, 1001

and

111001

correspond to the

2

's complement representation of which one of the following sets of number ?

The

8255

Programmable Peripheral Interface is used as described below. An A/D converter is interfaced to a microprocessor through

8255.

The conversion is initiated by a signal from the

8255

on Port C. A signal on Port C causes data to be strobed into Port A. Two computers exchange data using a pair of

8255 \mathrm{s}

. Port A works as a …

The number of memory cycles required to execute the following

8085

instructions

\text{LDA 3000 H}

\text{LXI D, FOF 1 H}

would be

In the modulo-

6

ripple counter shown in the given figure, the output of the

2

-input gate is used to clear the J-K flip-flops. The

2

-input gate is

Consider the sequence of

8085

instructions given below.

\text{LXI H, 9258, MOV A, M, CMA, MOV M, A}

Which one of the following is performed by this sequence?

A Boolean function

f

of two variables

x

and

y

is defined as follows:

f(0,0)=f(0,1)=f(1,1)=1 ; \quad f(1,0)=0

Assuming complements of

x

and

y

are not available, a minimum cost solution for realizing

f

using only

2

-input NOR gates and

2

-input OR gates (each having unit cost) would have a total cost of

It is desired to multiply the numbers

0 \mathrm{AH}

by

0 \mathrm{BH}

and store the result in the accumulator. The numbers are available in registers

B

and

C

respectively. A Part of the

8085

program for this purpose is given below:

\qquad \qquad \text{MV1 A, 00H}

\text{Loop;}…....……….….

\qquad.…...…….....….

…

A

1 \; \mathrm{kHz}

sinusoidal signal is ideally sampled at

1500

samples/sec and the sampled signal is passed through an ideal low-pass filter with cut-off frequencey

800 \mathrm{~Hz}

. The output signal has the frequency

A rectangular pulse train

s(t)

as shown in the figure is convolved with the signal

\cos ^{2}\left(4 p \times 10^{3} t\right)

. The convolved signal will be a

A causal

\text{LTI}

system is described by the difference equation

2 y[n]=\alpha y[n-2]-2 x[n]+\beta x[n-1]

The system is stable only if

A causal system having the transfer function

\mathrm{H}(s)=\frac{1}{s+2}

is excited with

10 u(t)

. The time at which the output reaches

99 \%

of its steady state value is