Question 1

A Differential Amplifier should have collector resistor's value (RC1 & RC2) as

Accepted Answer

For a differential amplifier to function properly, the collector resistors (RC1 & RC2) should have equal values to ensure symmetry in the circuit, which is essential for balanced operation and effective differential signal amplification. Hence, option A (5kΩ, 5kΩ) is correct.

Question 2

A Differential Amplifier amplifies

Accepted Answer

A differential amplifier amplifies the difference between two input voltages, not the higher voltage, smaller voltage, or their sum.

Question 3

The value of emitter resistance in Emitter Biased circuit are RE1=25k? & RE2=16k?. Find RE

Accepted Answer

RE = RE1 || RE2 = (25kΩ * 16kΩ) / (25kΩ + 16kΩ) = 9.756kΩ

Question 4

If output is measured between two collectors of transistors, then the Differential amplifier with two input signal is said to be configured as

Accepted Answer

A differential amplifier with two input signals measured between two collectors is configured as Dual Input Balanced Output. This configuration allows for the amplification of the difference between the two input signals while rejecting any signals that are common to both inputs, providing a balanced output.

Question 5

A differential amplifier is capable of amplifying

Accepted Answer

A differential amplifier can amplify both AC and DC input signals because it amplifies the difference between two input signals, which can be either AC, DC, or a combination of both.

Question 6

In ideal Differential Amplifier, if same signal is given to both inputs, then output will be

Accepted Answer

In an ideal differential amplifier, the output is the difference between the two input signals. If the same signal is applied to both inputs, the difference is zero, resulting in a zero output.

Question 7

An emitter bias Dual Input Balanced Output differential amplifier has VCC=20v, ?=100, VBE=0.7v, RE=1.3k?. Find IE

Accepted Answer

In an emitter bias dual input balanced output differential amplifier, the emitter current (IE) can be calculated using the formula IE = (VCC - VBE) / (2*RE + (RE/β)). Plugging in the given values: IE = (20 - 0.7) / (2*1300 + (1300/100)) = 7.42mA.

Question 8

Find IC, given VCE=0.77v, VCC=10v, VBE=0.37v and RC=2.4k? in Dual Input Balanced Output differential amplifier

Accepted Answer

The answer of Find IC, given VCE=0.77v, VCC=10v, VBE=0.37v and...

Question 9

For the circuit shown below, determine the Output voltage (Assume ?=5, differential input resistance=12 k?)

Accepted Answer

The output voltage of an operational amplifier in a non-inverting configuration can be calculated using the formula Vout = Vin(1 + Rf/Rin), where Vin is the input voltage, Rf is the feedback resistance, and Rin is the input resistance. Given that β = 5 (which implies a feedback factor, suggesting that Rf/Rin = 5), and assuming the differential input resistance is 12kΩ does not directly affect the calculation since it's about the differential input, not the feedback or input resistance directly. If we assume a standard input voltage of 1V for simplicity (since the actual Vin is not provided), the output voltage Vout = 1V(1 + 5) = 6V. However, none of the provided options match this calculation, suggesting a misunderstanding in the question's given values or a missing piece of information (like the actual Vin value). Given the options and the information, without the specific input voltage, the exact calculation as per the formula cannot match the provided choices. Therefore, the correct answer based on standard operational amplifier calculations and the information provided cannot be accurately determined without assuming or knowing the input voltage. If we were to work backwards from the options provided and considering a feedback factor of 5, it suggests an amplification factor, but without the actual input voltage, pinpointing how the options were derived is speculative.

Question 10

In a Single Input Balanced Output Differential amplifier, given VCC=15v, RE = 3.9k?, VCE=2.4 v and re=250?. Determine Voltage gain

Accepted Answer

The voltage gain (Av) of a differential amplifier in a single input balanced output configuration can be calculated using the formula Av = -Rc/(2re + RE). However, the given information does not directly provide Rc, but we can infer it from VCC and VCE. Given VCC = 15V and VCE = 2.4V, and assuming the transistor is in active mode, the collector current (Ic) and emitter current (Ie) can be approximated to be the same due to the transistor's operation. However, without the collector resistor (Rc) value or the collector current (Ic), we cannot directly calculate Rc from the given information. The formula for voltage gain in the question context seems to be misapplied or missing critical information for direct calculation. In a typical scenario, if we had the collector resistor value or could calculate it, and assuming the question intends for a simplified approach ignoring the role of RE in the internal emitter resistance (re') calculation, the voltage gain (Av) formula for a single input balanced output configuration simplifies to Av ≈ -Rc/re, where re is the intrinsic emitter resistance. Given re = 250Ω, without Rc, we cannot proceed directly. However, assuming a misunderstanding in the question's presentation and that it intended for a simplified direct calculation or provided incorrect parameters for the typical formula application, one might attempt to use an approximation or a different formula based on the provided values. In educational contexts, it's crucial to ensure the question aligns with the expected formula and provided parameters. For a more accurate response or calculation, additional information or clarification on the intended formula and parameters (like Rc or the correct approach to calculate Av with the given values) is necessary.

Question 11

The characteristic impedance of a quarter wave transformer with load and input impedances given by 30 and 75 respectively is

Accepted Answer

The characteristic impedance ($Z_0$) of a quarter wave transformer can be calculated using the formula $Z_0 = \sqrt{Z_L Z_{in}}$, where $Z_L$ is the load impedance and $Z_{in}$ is the input impedance. Substituting $Z_L = 30\Omega$ and $Z_{in} = 75\Omega$, we get $Z_0 = \sqrt{30 \times 75} = \sqrt{2250} \approx 47.43\Omega$.

Question 12

For a matched line, the input impedance will be equal to

Accepted Answer

For a matched line, the input impedance is equal to the characteristic impedance of the line. This is a fundamental principle in transmission line theory, ensuring maximum power transfer and minimizing reflections.

Question 13

The reflection coefficient lies in the range of

Accepted Answer

The reflection coefficient is a measure of the amount of light that is reflected from a surface. It is defined as the ratio of the reflected intensity to the incident intensity. The reflection coefficient can range from 0 to 1, where 0 indicates that no light is reflected and 1 indicates that all light is reflected.

Question 14

When the ratio of load voltage to input voltage is 5, the ratio of the characteristic impedance to the input impedance is

Accepted Answer

The ratio of the characteristic impedance to the input impedance in a transmission line is equal to the square root of the load impedance to the input impedance ratio. Since the voltage ratio is given as 5, and assuming the system is lossless, this implies the impedance ratio is also 5. Therefore, the square root is not directly applicable here, and the correct interpretation is that the characteristic impedance to input impedance ratio is directly equal to the voltage ratio, which is 5.

Question 15

The power of the transmitter with a radiation resistance of 12 ohm and an antenna current of 3.5A is

Accepted Answer

The power of the transmitter can be calculated using the formula P = I^2 * R, where I is the current and R is the radiation resistance. Substituting the given values, P = (3.5)^2 * 12 = 147 watts.

Question 16

The group delay of the wave with phase constant of 62.5 units and frequency of 4.5 radian/sec is

Accepted Answer

Group delay is calculated as the derivative of the phase constant with respect to angular frequency. Given the phase constant is 62.5 and frequency is 4.5 rad/s, the group delay is 62.5/4.5 = 13.88.

Question 17

5 is" The maximum impedance of a transmission line 50 ohm and the standing wave ratio of

Accepted Answer

The answer of 5 is" The maximum impedance of a...

Question 18

The average power in an electromagnetic wave is given by

Accepted Answer

The average power in an electromagnetic wave is represented by the Poynting vector, which quantifies the power per unit area flowing through a surface perpendicular to the direction of propagation of the wave.

Question 19

The characteristic impedance of a transmission line is normally chosen to be

Accepted Answer

The characteristic impedance of a transmission line is typically chosen to be either 50 ohms or 75 ohms. 50 ohms is commonly used for radio and other RF applications, while 75 ohms is standard for television and video.

Question 20

Identify the material which is not present in a transmission line setup.

Accepted Answer

Oscillators are not a part of the transmission line setup. They are electronic circuits that generate a continuous, oscillating electronic signal, usually a sine wave or a square wave. Transmission lines, such as waveguides, along with cavity resonators and antennas, are components used to guide, resonate, or radiate electromagnetic waves, not generate them.

Quiz 4: Electronics and Transmission Line