Define sheet resistance.

Define sheet resistance.
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Answer :

Sheet resistance is defined as the resistance in ohms /square offered by the diffused area.
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What is the proper procedure for suppressing electrical noise in a mobile station? A. Apply shielding and filtering where necessary B. Insulate a all plain sheet metal surfaces from each other C. Apply anti-static spray liberally to all nonmetallic D. Install filter capacitors in series with all dc wiring

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Last Answer : A. Apply shielding and filtering where necessary

Factors that determine the radiation resistance of an antenna A. Transmission line length and height of antenna B. The location of the antenna with respect to nearby objects C. It is a constant for all antennas since it is physical D. Sunspot activity and the time of day

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Last Answer : B. The location of the antenna with respect to nearby objects

An antenna “efficiency” is computed by using one of the following equations. A. Efficiency = (radiation resistance / transmission resistance) B. Efficiency = (total resistance / radiation resistance) x 100% C. Efficiency = (effective radiated power / transmitter output) x 100% D. Efficiency = (radiation resistance / total resistance) x 100%

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The square of the thermal noise voltage generated by a resistor is proportional to A. its resistance B. its temperature C. the bandwidth over which it is measured D. All of the above

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What is the noise voltage across a 300Ω input resistance to a TV set with a 6MHz bandwidth and temperature of 30˚C? A. 2.3 µV B. 3.8µV C. 5.5µV D. 5.4µV

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A receiver connected to an antenna whose resistance is 50 Ω has an equivalent noise resistance of 30Ω. Calculate its equivalent noise temperature if the noise figure is equal to 1.6. A. 17.4 K B. 174K C. 1.74K D. 17K

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Calculate the noise figure of the receiver whose RF amplifier has an input resistance of 1000Ω and an equivalent shot-noise resistance of 2000Ω, a gain of 25 and load resistance of 125 kΩ. Given that the bandwidth is 1.0MHz and the temperature is 20˚C, and that the receiver is connected to an antenna with an impedance of 75Ω. A. 30.3 B. 3.03 C. 303 D. .303

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The first stage of a two-stage amplifier has a voltage gain of 10, a 600 Ω input resistor, a 1600Ω equivalent noise resistance and 27kΩ output resistor. For the second stage, these values are 25, 81kΩ, 19kΩ, and 1MΩ, respectively. Calculate the equivalent input-noise resistance of this two stage amplifier. A. 2,518 kΩ B. 2,518 Ω C. 251.8 Ω D. 12,518 Ω

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A transmitted signal 5 meters in wavelength is received by an antenna coil having a 50-Ω resistance and a 0.01 H inductance. What is the capacitance of the tuner shunting the antenna coil at this point? A. 0.704 fF B. 0.704 μF C. 0.704 nF D. 0.704 mF

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Description : What would happen if the base resistor has zero resistance?

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What would happen if the base resistor has zero resistance?

Description : What would happen if the base resistor has zero resistance?

Last Answer : If the base resistance is zero, then the base current is very high. Since, we know that the base current is directly proportional to the collector current with the multiplying factor of current ... high. In this time, the transistor operates in saturation region and finally it is being destroyed.

Transmission lines when connected to antenna have A. capacitive load B. resistive load whose resistance is less than characteristics impedance C. resistive load at the resonant frequency D. resistive load whose resistance is greater than the characteristic impedance of the line

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ECE Board Exam March 1996 A receiver connected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. What is the receiver’s noise temperature? A. 754 K B. 464 K C. 174 K D. 293 K

Description : ECE Board Exam March 1996 A receiver connected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. What is the receiver’s noise temperature? A. 754 K B. 464 K C. 174 K D. 293 K

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Define Piezoelectric effect.

Description : Define Piezoelectric effect.

Last Answer : When applying mechanical energy to some type of crystals called piezoelectric crystals the mechanical energy is converted into electrical energy is called piezoelectric effect.

Define non-inverting amplifier?

Description : Define non-inverting amplifier?

Last Answer : The input is applied to the non-inverting input terminal and the inverting terminal connected to the ground.

Define slew rate?

Description : Define slew rate?

Last Answer : Slew rate can be defined as the maximum rate of change of output voltage of op-amp with respect to time.

Define input bias current?

Description : Define input bias current?

Last Answer : It is defined as the average of the currents entering into the input terminals of an op-amp.

Define input offset current?

Description : Define input offset current?

Last Answer : It is defined as the algebraic difference between the current entering the inverting and non-inverting terminal of an op-amp.

Define input offset voltage?

Description : Define input offset voltage?

Last Answer : It is defined as the voltage that must be applied between the input terminals of an op-amp to nullify the output.

Define loading?

Description : Define loading?

Last Answer : A large value of Rc cannot be used in a circuit since,a large value of resistance requires a large chip area.For large Rc, quiescent drop across it increases and hence a large power supply is required ... source can also be used as an active load for an amplifier to obtain a very large voltage gain.

Define current amplification factor?

Description : Define current amplification factor?

Last Answer : It is defined as the ratio of change in output current to the change in input current at constant other side voltage.

Define PIV .

Description : Define PIV .

Last Answer : Peak inverse voltage is the maximum reverse voltage that can be applied to the PN junction without damage to the junction.

Define the term diffusion current?

Description : Define the term diffusion current?

Last Answer : A concentration gradient exists, if the number of either electrons or holes is greater in one region of a semiconductor as compared to the rest of the region. The holes and electron ... concentration. This process in called diffusion and the current produced due this movement is diffusion current.

Define drift current?

Description : Define drift current?

Last Answer : When an electric field is applied across the semiconductor, the holes move towards the negative terminal of the battery and electron move towards the positive terminal of the battery. This drift movement of charge carriers will result in a current termed as drift current.

Define Monostable Multivibrators

Description : Define Monostable Multivibrators

Last Answer : The monostable multivibrator or one –shot requires an external signal called a trigger to force the circuitinto a quasi stable state for a particular time or delay.

Define Astable Multivibrators.

Description : Define Astable Multivibrators.

Last Answer : The astable Multivibrators toggles between one state and the other without the influence of any other external control signal. It is also called as free running multivibrator.

Define Multivibrators. Mention its types.

Description : Define Multivibrators. Mention its types.

Last Answer : Multivibrators are regenerative circuits, Which are mainly used in timing applications. Based on their operational characteristics they can be classified into • Astable Multivibrators • Monostable Multivibrators • Bistable Multivibrators

Define load regulation.

Description : Define load regulation.

Last Answer : Load regulation is defined as the change in output voltage for a change in load current. It is expressed in millivolts or as a percentage of the output voltage. 

Define line regulation.

Description : Define line regulation.

Last Answer : Line regulation is defined as the percentage change in the output voltage for a change in the input voltage.It is expressed in millivolts or as a percentage of the output voltage. 

Define slope overload noise and granular noise.

Description : Define slope overload noise and granular noise.

Last Answer : Slope overload noise is introduced due to the use of a step size delta is too small To follow some portions of the waveform with a step size.   Granular noise results from using a step size that is too large in parts of the waveform having a small slope. 

Define Delta modulation.

Description : Define Delta modulation. 

Last Answer : Delta modulation is a technique in which derivative of the signal is quantized. The delta modulation shows slope overload for fast input signals and their performance is dependent on input signal frequency.

Define Dither.

Description : Define Dither.

Last Answer : It is a very small amount of random noise(white noise) which is added to the input before A/D conversion to improve the performance of A/D converter.

Define quantization error.

Description : Define quantization error.

Last Answer : In A/D converter the smallest digital step is due to the LSB and it can be made smaller only by increasing the number of bits in the digital representation. This error is called quantization error.

Define sample period and hold period.

Description : Define sample period and hold period.

Last Answer : The time during which the voltage across the capacitor in sample and hold circuit is equal to the input voltage is called sample period.The time period during which the voltage across the capacitor is held constant is called hold period. 

Define accuracy of converter.

Description : Define accuracy of converter.

Last Answer : Absolute accuracy: It is the maximum deviation between the actual converter output & the ideal converter output.  Relative accuracy: It is the maximum deviation after gain & offset errors have been removed. ... of a converter is also specified in form of LSB increments or % of full scale voltage.

Define resolution of a data converter.

Description : Define resolution of a data converter.

Last Answer : The resolution of a converter is the smallest change in voltage which may be produced at the output or input of the converter. Resolution (in volts)= VFS/2n-1=1 LSB increment. The resolution of an ADC is defined as the smallest change in analog input for a one bit change at the output.