Unit 5 - Practice Quiz

1 What does the letter 'h' stand for in the h-parameter model of a transistor?

2 How many ports does the standard transistor hybrid model have?

3 What is the unit of the input parameter (or ) in the hybrid model?

4 Which two variables are considered as the independent variables in standard h-parameter equations?

5 Which h-parameter is determined from the slope of the input characteristics while keeping the output voltage constant?

6 What does the parameter represent in a Common Emitter configuration?

7 What is the unit of the output admittance parameter, ?

8 The h-parameter equivalent circuit is primarily used for which type of analysis?

9 In the h-parameter model for a Common Emitter amplifier, what is commonly known as?

10 In the standard h-parameter equivalent circuit, the dependent current source is represented by which expression?

11 Which transistor configuration is most widely used because it provides both moderate voltage and moderate current gain?

12 Which amplifier configuration offers the lowest input impedance?

13 Which transistor configuration is also known as an Emitter Follower?

14 What is the typical phase shift between the input and output voltage in a Common Emitter amplifier?

15 What is the primary purpose of cascading transistor amplifier stages?

16 Which type of coupling is most commonly used to block DC components while passing AC signals between cascaded stages?

17 What generally happens to the overall bandwidth when multiple identical amplifier stages are cascaded?

18 If an n-stage amplifier has individual stage voltage gains of , what is the total overall voltage gain ()?

19 When individual stage gains are expressed in decibels (dB), how is the total overall gain of the n-stage amplifier calculated?

20 What is the main disadvantage of using direct coupling in an n-stage cascaded amplifier?

21 In a two-port hybrid model of a transistor, the input voltage and output current are expressed as dependent variables. Which of the following sets of equations correctly represents this model?

22 What is the primary reason for preferring hybrid (h) parameters over Z or Y parameters in low-frequency transistor circuit analysis?

23 When determining the h-parameters from the common-emitter (CE) characteristics, how is the parameter mathematically obtained?

24 Which portion of the static characteristics of a CE transistor is used to evaluate the reverse voltage transfer ratio, ?

25 For a standard transistor amplifier represented by its exact h-parameter model connected to a load impedance , what is the expression for the current gain ?

26 If the parameter is assumed to be negligibly small (), what is the approximate input impedance of the amplifier?

27 The voltage gain of a transistor amplifier can be expressed in terms of its current gain , input impedance , and load impedance . Which of the following is the correct relationship?

28 In the derivation of output admittance using h-parameters, what condition is applied to the source voltage ?

29 Which transistor amplifier configuration provides both high voltage gain and high current gain, making it the most suitable for maximizing power gain?

30 An application requires an amplifier stage with very high input impedance and very low output impedance to act as a buffer. Which configuration is best suited for this?

31 Regarding the phase relationship between the input and output signals, which of the following statements is true for low-frequency transistor amplifiers?

32 When two transistor amplifier stages are cascaded, how does the input impedance of the second stage affect the first stage?

33 If two identical CE amplifier stages, each having an unloaded voltage gain of , are cascaded using RC coupling, what can be said about the overall voltage gain ?

34 Which interstage coupling method in cascaded amplifiers provides the best direct-current (DC) isolation while completely blocking DC bias transfer between stages?

35 For an n-stage cascaded amplifier where each stage has a lower cut-off frequency , what is the approximate overall lower cut-off frequency ?

36 What is the effect on the upper cut-off frequency () and the overall bandwidth when identical amplifier stages are cascaded?

37 An amplifier consists of 3 cascaded stages with individual voltage gains of 20 dB, 15 dB, and 10 dB. What is the overall voltage gain of the system in decibels?

38 In an n-stage RC coupled amplifier, as the number of stages increases significantly, how does the frequency response curve behave around the midband?

39 In a two-stage cascaded amplifier, if the first stage has a current gain of and the second stage has a current gain of , the overall current gain is computed as . What condition is implicitly necessary for in this straightforward multiplication?

40 What are the dimensions (units) of the h-parameters , , , and respectively?

41 In a linear two-port network represented by its exact h-parameter matrix, what is the expression for the short-circuit output admittance (i.e., when the input voltage ) in terms of the h-parameters and the determinant ?

42 Given the exact input impedance of a two-port network , under what condition will the input impedance become strictly independent of the load impedance ?

43 A Common-Emitter (CE) transistor is converted to a Common-Base (CB) model. Which of the following represents the exact analytical expression for in terms of CE h-parameters?

44 When extracting from the input characteristics (plot of vs. ) for various values of , it is observed that is extremely small. To properly measure this dynamically at low frequencies, which ideal test condition must be enforced?

45 Due to high-level injection effects (Webster effect) at very large base currents, how do the graphically determined values of and typically deviate compared to their nominal active region values?

46 If the Early voltage of a BJT is considered in the derivation of exact low-frequency h-parameters, what is the approximate analytical relationship linking and in the forward-active region?

47 For a Common-Emitter amplifier driven by a source with internal resistance , the exact output admittance is given by . If a small unbypassed emitter resistor is added, how does the effective output admittance change?

48 In a given amplifier analyzed via h-parameters, the current gain . To obtain an overall voltage gain strictly dependent on the ratio of to , and virtually independent of transistor variations, which condition must hold true?

49 Consider the exact power gain of an amplifier. Substituting the exact h-parameter expressions for and , which values of maximizes the operating power gain (assuming purely resistive parameters)?

50 For a CE amplifier, the transducer power gain , which compares power delivered to the load versus power available from the source (with internal resistance ), is maximized when:

51 When comparing the hybrid determinants of the three transistor configurations, we find that , , and follow specific analytical relationships. Which of the following is the correct exact relation for in terms of CE parameters?

52 Which configuration exhibits a short-circuit current gain () whose magnitude is heavily dependent on temperature fluctuations and operating point, while simultaneously possessing a hybrid determinant ?

53 A system requires an amplifier stage to drive a highly capacitive load (low impedance at high frequencies) from a high-impedance source. Based on exact h-parameter analysis, why is cascading a CC stage followed by a CB stage physically optimal over a single CE stage?

54 In a two-stage direct-coupled CE-CE amplifier, the effective load of the first stage is solely the input impedance of the second stage, . If the second stage is subjected to an extreme load such that its output is dynamically short-circuited (), what is the exact voltage gain of the first stage, ?

55 Consider a Darlington amplifier (CC-CC cascade) formed by two identical transistors with parameters and . Under the assumption that and are negligible, what is the exact synthesized input impedance of the Darlington pair if it is terminated with an emitter resistor ?

56 A Cascode amplifier comprises a CE stage driving a CB stage. If the CE stage has a transconductance and the CB stage has a current gain , what makes the Miller capacitance of the CE stage virtually negligible in this cascade configuration?

57 In a bootstrapped Darlington pair used to obtain ultra-high input impedance, a feedback capacitor is connected between the emitter of the second transistor and the junction of the biasing resistors. How does bootstrapping mathematically alter the effective parallel bias resistance ?

58 An -stage cascaded amplifier is constructed using strictly identical non-interacting stages, each with a lower cutoff frequency . What is the exact expression for the overall lower 3-dB cutoff frequency of the entire cascade?

59 For large , the bandwidth shrinkage factor for identical cascaded amplifier stages can be approximated using a Taylor series expansion. Which of the following is the correct asymptotic approximation as ?

60 When computing the transient response of an -stage interacting cascaded amplifier, the overall rise time can be estimated from the individual rise times using the empirical variance-sum formula. If all stages are identical with individual rise time , what is the overall rise time and the resulting effect on the overall bandwidth ?