This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The CE Short Circuit Current Frequency Response”.

1. What is the value of input resistance in the CE short circuit current frequency response model?

a) h_{oe}

b) h_{ib}

c) h_{ic}

d) h_{ie}

View Answer

Explanation: The input resistance of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. The input resistance is universally expressed as h

_{ie}. This is also the same for approximate as well as exact hybrid models.

2. How do we calculate the value of I_{C} in the CE short circuit current frequency response model?

a) I_{C} = h_{re} × I_{B}

b) I_{C} = -h_{re} × I_{B}

c) I_{C} = h_{fe} × I_{B}

d) I_{C} = -h_{fe} × I_{B}

View Answer

Explanation: The collector current of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. It is expressed as the product of h

_{fe}× I

_{B}. This is the same for approximate hybrid models as well.

3. What is the value of current gain in the CE short circuit current frequency response model?

a) h_{fe}

b) -h_{fe}

c) h_{re}

d) –h_{re}

View Answer

Explanation: The current gain of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. The current gain h

_{fe}is the forward transfer characteristics and is used to calculate the current gain in common emitter amplifiers.

4. What is the value of voltage gain in the CE short circuit current frequency response model?

a) h_{fe} × R_{L} / h_{re}

b) –h_{fe} × R_{L} / h_{re}

c) h_{fe} × R_{L} / h_{ie}

d) –h_{fe} × R_{L} / h_{ie}

View Answer

Explanation: The voltage gain of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. The voltage gain is equal to -h

_{fe}× R

_{L}/ h

_{ie}where, R

_{L}is load resistance, h

_{ie}is input resistance and -h

_{fe}is the current gain.

5. What is the magnitude of voltage generated at emitter circuit of a CE short circuit current frequency response model?

a) h_{re} × h_{fe} / I_{b} × R_{L}

b) h_{re} × h_{fe} × I_{b} × R_{L}

c) h_{re} × h_{fe} / I_{C} × R_{L}

d) h_{re} × h_{fe} × I_{C} × R_{L}

View Answer

Explanation: The magnitude of voltage generated at emitter circuit of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. The magnitude of voltage generated is equal to h

_{re}× h

_{fe}× I

_{b}× R

_{L}where, R

_{L}is load resistance and I

_{b}is the base current.

6. What is the value of output resistance in the CE short circuit current frequency response model?

a) ∞

b) 0

c) h_{ic}

d) h_{ie}

View Answer

Explanation: The output resistance in a simplified common emitter hybrid model is calculated as the ratio of collector voltage over collector current while V

_{S}is equal to zero and R

_{L}is omitted. Due to this configuration I

_{C}is equal to zero and hence output resistance is infinite.

7. What is the value power gain in the CE short circuit current frequency response model?

a) A_{V} – A_{I}

b) A_{V} + A_{I}

c) A_{V} × A_{I}

d) A_{V} / A_{I}

View Answer

Explanation: The power gain in a simplified common emitter hybrid model is calculated as the product of voltage gain and power gain. It is expressed as A

_{V}× A

_{I}. It can also be further simplified as A

_{I}

^{2}× R

_{L}/ R

_{i}, where R

_{L}is load resistance and R

_{i}is input resistance.

8. What is the value of overall current gain in the CE short circuit current frequency response model while considering R_{S}?

a) A_{I} × I_{B} / I_{S}

b) A_{I} × I_{C} / I_{S}

c) A_{I} × I_{S} / I_{C}

d) A_{I} × I_{S} / I_{B}

View Answer

Explanation: The current gain in a simplified common emitter hybrid model while considering R

_{S}is calculated as the product of current gain without external parameters and the ratio of base current and external applied current. It is expressed as A

_{I}× I

_{B}/ I

_{S}. Where, I

_{S}is the external applied current on the amplifier.

9. What is the value of overall voltage gain in the CE short circuit current frequency response model while considering R_{S}?

a) V_{B} / V_{S}

b) V_{C} / V_{S}

c) V_{B} × V_{S}

d) V_{C} × V_{S}

View Answer

Explanation: The overall voltage gain in a simplified common emitter hybrid model while considering R

_{S}is calculated as ratio of base voltage over the applied external voltage. It is expressed as V

_{B}/ V

_{S}. Where, V

_{S}is the external applied voltage on the amplifier.

10. We use CE short circuit current frequency response models to obtain approximate values.

a) True

b) False

View Answer

Explanation: It is more practical to calculate the approximate values of voltage and current gains instead of computing the exact values of a common emitter amplifier circuit. We use a simplified common emitter hybrid model to obtain these approximate values without reducing the accuracy.

**Sanfoundry Global Education & Learning Series – Electronic Devices and Circuits.**

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