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Objective Questions

Short notes

Objective questions (Answers are given below)

Silicon is preferred for manufacturing Zener
diodes because it
(a) is relatively cheap
(b) needs lower doping level
(c) has higher temperature and current
capacity
(d) has lower break-down voltage.
When used in a circuit, a Zener diode is always
(a) forward-biased
(b) connected in series
(c) troubled by overheating
(d) reverse-biased.
The main reason why electrons can tunnel
through a P-N junction is that
(a) they have high energy
(b) barrier potential is very low
(c) depletion layer is extremely thin
(d) impurity level is low.
The IP/IV ratio of a tunnel diode is of primary
importance in (a) determining tunneling speed of electrons (b) the design of an oscillator (c) amplifier designing(d) computer applications
Mark the INCORRECT statement. A varactor
diode
(a) has variable capacitance
(b) utilizes transition capacitance of a
junction
(c) has always a uniform doping profile
(d) is often used as an automatic frequency
control device.
The microwave device used as an oscillator
within the frequency range 10-1000 GHz is
……………………….. diode.
(a) Schottky
(b) IMPATT
(c) Gunn
(d) Step Recovery.
A PIN diode is frequently used as a
(a) peak clipper
(b) voltage regulator
(c) harmonic generator
(d) switching diode for frequencies upto
GHz range.
Mark the WRONG statement. A Schottky
diode
(a) has no depletion layer
(b) has metal-semiconductor junction
(c) has fast recovery time
(d) is a bipolar device
(e) is also called hot-carrier diode
(f) can easily rectify high-frequency
signals.
A special purpose diode which uses metals
like gold, silver or platinum on one side of
the junction, n-type doped silicon on another
side and has almost no charge storage in the
junction, is a
(a) Schotty diode
(b) tunnel diode
(c) varactor diode
(d) zener diode
A step-recovery diode
(a) has an extremely short recovery time
(b) conducts equally well in both directions
(c) is mainly used a harmonic generator
(d) is an ideal rectifier of high-frequency
signals.
A semiconductor device that resembles a
voltage variable capacitor is called diode.
(a) tunnel
(b) PIN
(c) Schottky
(d) varactor
A diode that has no depletion layers and
operates with hot carriers is called …… diode.
(a) Schottky
(b) Gunn
(c) step recovery
(d) PIN
In switching devices, gold doping is used to
(a) improve bonding
(b) reduce storage time
(c) increase the mobility of the carrier
(d) protect the terminals against corrosion
When the reverse bias voltage of a varactor
diode increases, its
(a) capacitance decreases
(b) lealkage current decreases
(c) negative resistance increases
(d) depletion zone decreases.
Which of the following are negativeresistance
microwave diodes oscillator
applications ?
(a) Gunn
(b) IMPATT
(c) step recovery
(d) both (a) and (b)
(e) both (b) and (c).
A negative-resistance microwave diode having
a thin slice of a semiconductor material
sandwiched between two metal conductors
is called …………… diode.
(a) Schottky
(b) PIN
(c) Gunn
(d) varactor.
Zener diodes are used primarily as
(a) rectifiers
(b) voltage regulators
(c) oscillators
(d) amplifiers.

The diode which is often used for voltage
regulation in electronic circuits is called ……
diode
(a) zener (b) varactor
(c) silicon (d) germanium.
Avalanche photodiodes are preferred over
PIN diodes in optical communication systems
because of
(a) speed of operation
(b) higher sensitivity
(c) larger bandwidth
(d) larger power handling capacity