Description : The transistor with the lowest noise figure in the microwave region is a A. MOSFET B. Dual-gate MOSFET C. JFET D. MESFET
Last Answer : D. MESFET
Description : When compared to the JFET, what is the input impedance of the MOSFET?
Last Answer : The MOSFET has a higher input impedance.
Description : State advantages of MOSFET over JFET.
Last Answer : ➨It can be operated in either enhancement mode or depletion mode. ➨MOSFET have much higher input impedance compare to JFET. ➨They have high drain resistance due to lower resistance of channel. ➨It is easy to manufacture. ➨They support high speed of operation compare to JFETs.
Description : Compare JFET with MOSFET.
Last Answer : Particulars JFET MOSFET 1) Type Voltage controlled device Voltage controlled device 2) Mode of operation Operates only in depletion mode Operates in depletion and enhancement ... 6) Gate connection Not isolated from substrate Isolated by SiO2 layer from substrate
Description : A depletion MOSFET differs from a JFET in the sense that it has no (A) channel (B) gate (C) P-N junctions (D) substrate
Last Answer : A depletion MOSFET differs from a JFET in the sense that it has no P-N junctions
Description : Which of the following types of noise becomes of great importance at frequencies? A. Shot noise B. Random noise C. Impulse noise D. Transit-time noise
Last Answer : D. Transit-time noise
Description : Atmospheric noise becomes less severe at frequencies A. above 30 MHz B. below 30 MHz C. above 3000 kHz D. below 3000kHz
Last Answer : A. above 30 MHz
Description : Atmospheric noise or static is not a great problem A. at frequencies below 20 MHz B. at frequencies below 5 MHz C. at frequencies above 30 MHz D. at frequencies above 1 MHz
Last Answer : C. at frequencies above 30 MHz
Description : What noise is observable at frequencies in the range from about 8 MHz to somewhat 1.5 GHz? A. Industrial noise B. Atmospheric noise C. Space noise D. Shot noise
Last Answer : C. Space noise
Description : When no signal is being received, the loudspeaker is not entirely silent as a result of the presence of A. parasitic oscillations in some of the receiver stages. B. negative feedback in each stage. C. spurious frequencies as a result of improper neutralization. D. internal receiver noise.
Last Answer : D. internal receiver noise.
Description : The band of frequencies least susceptible to atmospheric noise and interference is: A. 30 – 300 kHz B. 300 – 3000 kHz C. 3 – 30 MHz D. 300 – 3000 MHz
Last Answer : D. 300 – 3000 MHz
Description : What is the mixing process? A. Distortion caused by auroral propagation B. The combination of two signals to produce sum and difference frequencies. C. The elimination of noise in wideband receiver by phase differentiation D. The elimination of noise in a wideband receiver by phase comparison
Last Answer : B. The combination of two signals to produce sum and difference frequencies.
Description : Atmospheric noise is less at severe frequencies above A. Audio level B. 30 MHz C. 10 GHz D. 1 GHz
Last Answer : B. 30 MHz
Description : Emission on a frequency or frequencies immediately outside the necessary bandwidth which result from the modulation process except spurious emission. A. Radiation B. Noise C. Out of the band D. Interference
Last Answer : C. Out of the band
Description : Extra-terrestrial noise is observable at frequencies from A. 0 to 20 KHz B. Above 2 GHz C. 8 to 1.43 GHz D. 5 to 8 GHz
Last Answer : C. 8 to 1.43 GHz
Description : One of the reasons why FDM is being replaced by TDM is A. noise is amplified with voice when an FDM system is used B. it is difficult to place channels side by side C. there is more time than frequency D. Most available frequencies has been used
Last Answer : A. noise is amplified with voice when an FDM system is used
Description : What does the noise weighting curve shows? A. Noise signals measured with a 144 handset B. Power levels of noise found in carrier systems C. The interfering effect of other frequencies in a voice ... a reference frequency of one kilohertz D. Interfering effects of signals compared with a 3-kHz tone
Last Answer : C. The interfering effect of other frequencies in a voice channel compared with a reference frequency of one kilohertz
Description : Which of the following noise must be considered at high frequencies (microwave frequencies)? (1) Shot noise (2) Random noise (3) Impulse noise (4) Transit time noise
Last Answer : Which of the following noise must be considered at high frequencies (microwave frequencies)? (1) Shot noise (2) Random noise (3) Impulse noise (4) Transit time noise
Description : Why JFET is called a unipolar transistor?
Last Answer : In JFET, the current conduction is either by electrons or holes and controlled by means of an electric field between the gate electrode and the conducting channel of the device, So it is called as a unipolar transistor.
Description : What is the importance of JFET?
Last Answer : A JFET acts like a voltage controlled device i.e. input voltage controls the output current. This is different from ordinary transistor where input current controls the output current. JFET has higher input impedance than that of a conventional transistor.
Description : What is pinch off voltage in JFET?
Last Answer : Pinch off voltage (VP): It is the minimum drain source voltage at which the drain current essentially becomes constant.
Description : What is JFET?
Last Answer : A junction FET is a three terminal semiconductor device in which current conduction is by one type of carrier (i.e.) electrons or holes.
Description : A porous material is far more efficient at high than low frequency absorption. How to improve sound absorption at lower frequencies using this absorber? A. Increase the thickness B. Decrease the thickness C. Mount with and airspace behind D. Both A and C above
Last Answer : D. Both A and C above
Description : The ___________ filter attenuates signals but passes frequencies below and above that band. A. low pass B. band pass C. band stop D. high pass
Last Answer : C. band stop
Description : Explain how MOSFET functions?
Last Answer : Ans:There are two ways in which a MOSFET can function. The first is known as depletion mode . When there is no voltage on the gate, the channel exhibits its maximum conductance . As the voltage ... application of a voltage to the gate. The greater the gate voltage, the better the device conducts.
Description : Explain working of MOSFET.
Last Answer : MOSFET is a special type of field-effect transistor ( FET ) that works by electronically varying the width of a channel along which charge carriers flow. The wider the channel, the better the ... source and the drain and is insulated from the channel by an extremely thin layer of metal oxide.
Description : What is MOSFET?
Last Answer : MOSFET stands for Metal oxide Semiconductor field effect transistor. A type of transistor that is controlled by voltage rather than current.
Description : One of the potential health effects of exposure to high levels of noise is called tinnitus (pron: ti - NI - tes), which means: w) a permanent loss of hearing. x) a persistent ringing ... ) a temporary loss of hearing, especially of upper frequencies. z) abdominal discomfort from low frequency noise.
Last Answer : ANSWER: X -- A PERSISTENT RINGING OR HISSING IN THE EARS AFTER EXPOSURE.
Description : Deemphasis in the receiver in effect attenuates modulating signal components and noise in what frequency range? A. dc B. low C. intermediate D. high
Last Answer : D. high
Description : What causes image interference? A. Low gain B. High IF C. Poor front-end selectivity D. Low signal-to-noise ratio
Last Answer : C. Poor front-end selectivity
Description : What do you call the single booster installed on the antenna dish of satellite receiver? A. Low noise amplifier B. Single amplifier C. Noise amplifier D. Rectifier
Last Answer : A. Low noise amplifier
Description : What is the advantage of PTM over PAM? A. All of these B. Low sampling rate is required C. Much better noise immunity D. Simpler to generate
Last Answer : C. Much better noise immunity
Description : A dielectric waveguide for the propagation of electromagnetic energy at light frequencies a. Stripline b. Microstrip c. Laser beam d. Fiber optics
Last Answer : d. Fiber optics
Description : Fiber optic cables operate at frequencies near a. 20MHz b. 200MHz c. 2GHz d. 800THz
Last Answer : d. 800THz
Description : A disadvantage of using a trap antenna. A. It will radiate harmonics B. It can only be used for single-bad operation C. It is too sharply directional at lower frequencies D. It must be neutralized
Last Answer : A. It will radiate harmonics
Description : In what range of frequencies are most omnidirectional horizontally polarized antennas used? A. VHF, UHF B. VLF, LF C. SH, EHF D. MF, HF
Last Answer : A. VHF, UHF
Description : How can multiple earth stations share a satellite on the same frequencies? A. Frequency reuse B. Multiplexing C. Mixing D. Frequency hopping
Last Answer : A. Frequency reuse
Description : Which of the following frequencies is normally used for distress and safety communications? A. 4209.5 kHz B. 490 kHz C. 518 kHz D. 2174.5 kHz
Last Answer : D. 2174.5 kHz
Description : What is the channel spacing for SITOR frequencies? A. 500 Hz B. 170 Hz C. 300 Hz D. 3 kHz
Last Answer : A. 500 Hz
Description : What is the channel spacing for MF-HF voice frequencies? A. 2.8 kHz B. 500 Hz C. 3.5 kHz D. 3 kHz
Last Answer : D. 3 kHz
Description : The American concert pitch A is equivalent to which if the following frequencies? A. 440 Hz B. 435 Hz C. 260 Hz D. 255 Hz
Last Answer : A. 440 Hz
Description : In cellular system, _____ defines the geographic distance that is required between cells using identical frequencies in order to avoid interference between the radio transmissions at these cells. A. frequency-reuse ratio B. distance-to-reuse ratio (D/R) C. reuse format plan ratio D. reuse factor
Last Answer : B. distance-to-reuse ratio (D/R)
Description : What device measures the angle between two radio frequencies and also the direction of propagation of a wave? A. Densimeter B. Absorption wavemeter C. Goniometer D. Ergometer
Last Answer : C. Goniometer
Description : A 1 Mhz carrier is amplitude modulated by a pure 200-Hz audio test tone. Which of the following combinations of frequencies represent the total content of the AM signal? A. 1 MHz and 200 Hz B. 1 MHz and 1000.2 kHz C. 999.8 kHz, 1000 kHz, and 1000.2 kHz D. 999.8 kHz and 1000.2 kHz
Last Answer : C. 999.8 kHz, 1000 kHz, and 1000.2 kHz
Description : The ratio of frequencies is termed. A. interval B. octave C. harmonics D. factor
Last Answer : A. interval
Description : What band of frequencies do these satellites operate? A. L band B. Ka band C. C band D. Ku band
Last Answer : A. L band
Description : Which band of frequencies used by military for its satellites and radar? A. C band B. X band C. L band D. P band
Last Answer : B. X band
Description : Frequencies above ______ kHz, are referred to as the radio frequencies. A. 20 B. 2 C. 10 D. 200
Last Answer : A. 20
Description : Electromagnetic waves of frequencies arbitrarily lower than 3,000 GHz, propagated in space without artificial guide. A. Space waves B. Terrestrial waves C. Mobile D. Hertzian waves
Last Answer : D. Hertzian waves
Description : Refers to a continuous tone generated in a local exchange terminal through a combination of two frequencies 350 Hz, and 440 Hz. A. Busy tone B. Call waiting tone C. Dial tone D. Standard tone
Last Answer : B. Call waiting tone