BJT Amplifier Question & Answers November 29, 2021 By WatElectronics This article lists 100 BJT Amplifier MCQs for engineering students. All the BJT Amplifier Questions & Answers given below include a hint and a link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up their fundamentals on BJT Amplifier. A BJT amplifier is a 3 terminal electronic type device with 2 ports namely the input port and output port. Its purpose is to amplify the applied input signal to strengthen the signal for obtaining desired output. The transistor is the major component of the BJT amplifier. These amplifiers are classified based on operation modes or regions like saturation, active, and cutoff region; configuration types like common emitter, common base, and common collector amplifier; and stages like a single stage, and multistage. All the 3 configurations of these transistors operate only in an active region. A Common Emitter based BJT amplifier has maximum gain compared to other BJT amplifiers configuration. They benefit in terms of high gain, low power operation, high frequency, and high efficiency. But limit in terms of radiation, noise generation, and stability. These amplifiers are employed in applications such as wireless communication, RF receivers, direct coupling amplifiers ultrasonic amplifiers, etc. 1). BJT is widely used as ________ components? Switches Oscillators Amplifiers All the above Hint 2). BJT is ___ type of source device? Current driven Voltage driven Load driven All the above Hint 3). Gain of BJT amplifier is _____? Close to 1 Zero 1 Infinity Hint 4). How many pins do a BJT comprises of? 1 2 3 4 Hint 5). In how modes do a BJT amplifier works in? 2 3 4 5 Hint 6). In how many configuration do a BJT amplifier can be arranged? 2 3 4 5 Hint 7). Which of the following is the input terminal of common base BJT amplifier? Emitter Base Collector All the above Hint 8). Which of the following is the output terminal of common base BJT amplifier? Emitter Base Collector All the above Hint 9). Which of the following terminal of common base BJT amplifier is grounded? Emitter Base Collector All the above Hint 10). Which of the following is the input terminal of common emitter BJT amplifier? Emitter Base Collector All the above Hint 11). Which of the following is the output terminal of common emitter BJT amplifier? Emitter Base Collector All the above Hint 12). Which of the following terminal of common emitter BJT amplifier is grounded? Emitter Base Collector All the above Hint 13). Which of the following is the input terminal of common collector BJT amplifier? Emitter Base Collector All the above Hint 14). Which of the following is the output terminal of common collector BJT amplifier? Emitter Base Collector All the above Hint 15). Which of the following terminal of common collector BJT amplifier is grounded? Emitter Base Collector All the above Hint Read more about oscillator. 16). A Common Emitter Based BJT amplifier acts as ___ type of amplifier? Current Voltage Load All the above Hint 17). What is the value of output of an common emitter basted BJT amplifier? Zero One Inverted Infinity Hint 18). What is the gain value of common emitter based BJT amplifier? High Low Zero Constant Hint 19). Which of the following is the value of base emitter voltage of common emitter BJT amplifier? 0.7V 0.5V 0.1V 0.2V Hint 20). Which of the following source is applied as input to BJT amplifier? AC DC AC-DC All the above Hint 21). A process of interchanging negative and positive values of voltage in a BJT amplifier is called______? Biasing Rectifier Amplification All the above Hint Read more about Biasing. 22). A device that enhances the strength of vulnerable signal is called _____? Biasing Amplification Rectification All the above Hint 23). A device that amplifies a weak signal to a stronger signal is called_____? Amplifier Rectifier Transmitter All the above Hint 24). Which of the following is the major disadvantage of an amplifier? Varies only signals magnitude Restriction on change in signals shape Varies shape of signal Both a and b Hint 25). Which of the following is the 1 st step while choosing an amplifier? Selection of configuration Biasing of amplifier Gain of the amplifier Output Hint BJT Amplifier Interview Questions and Answers 26). Which of the following is the 2 nd step while choosing an amplifier? Selection of configuration Biasing of amplifier Gain of the amplifier Output Hint 27). Which of the following is the 3 rd step while choosing an amplifier? Selection of configuration Biasing of amplifier Gain of the amplifier Output Hint 28). Identify the circuit configuration of BJT amplifier of below image? BJT Amplifier Configuration CE CC CB CBC Hint 29). Identify the circuit configuration of BJT amplifier of below image? BJT Amplifier Configuration CE CB CC CBC Hint 30). Identify the circuit configuration of BJT amplifier of below image? BJT Amplifier Configuration CE CB CC CBC Hint 31). All the BJT amplifiers are available in __ number of configuration? 1 2 3 4 Hint 32). The width of common emitter BJT amplifier ______ during positive cycle of operation? Increases Decreases Same Attenuates Hint 33). During positive half cycle of common emitter BJT amplifier the electrons flow ___ from emitter to collector? Increases Decreases Same Attenuates Hint 34). When the collector current of common emitter BJT amplifier increases then the voltage ___ across load? Drops Increases Decreases Constant Hint 35). During negative half wave of common emitter BJT amplifier ____ happens to forward bias voltage at emitter base junction? Reduces Increases Zero Constant Hint 36). The wave of common emitter BJT amplifier is of ____ phase shift with respect to input and output? 90 120 180 360 Hint 37). A non-inverting type amplifier has ___phase with input signal? 120 0 180 360 Hint 38). Which of the following are the components of common emitter BJT amplifier? Resistors AC generator Capacitors All the above Hint Read more about Resistors. 39). Which of the following component of common emitter BJT amplifier is used for biasing? Resistors AC generator Capacitors All the above Hint 40). How many types of resistors are used in common emitter BJT amplifier? 2 3 4 5 Hint 41). A capacitor in common emitter BJT amplifier that separates AC based signal and DC based biasing voltage is ____? Coupling capacitor Capacitor impedance Capacitor reactance All the above Hint 42). Which of the following is the formula for current gain of common emitter based amplifier? Change in collector current / Change in base current Change in collector current / Change in emitter current Change in base current / Change in emitter current All the above Hint 43). Which of the following is the formula for voltage gain of common emitter based amplifier? Current gain [ output collector resistance / input base resistance] Current gain [ output emitter resistance / input base resistance] Voltage gain [ output collector resistance / input base resistance] Both a and b Hint 44). Which of the following is the equation of base current of common emitter based amplifier? Ib = IB +ib Ib = IB - ib Ib = IB * ib Ib = IB /ib Hint 45). Which of the following is the equation of collector current of common emitter based amplifier? Ic=IC+ic Ic=IC/ic Ic=IC*ic Ic=IC-ic Hint 46). Which of the following is the equation of emitter current of common emitter based amplifier? Ie = IE +ie Ie = IE - ie Ie = IE / ie Ie = IE * ie Hint 47). Which of the following is the formula of circuit voltage gain of common emitter based BJT amplifier? –hfe/hie[Rc||RL] Hfe. RC. Rb/[(Rc+RL)(Rc+hie)] Av*Ai Hie Hint 48). Which of the following is the formula of circuit current gain of common emitter based BJT amplifier? –hfe/hie[Rc||RL] Hfe. RC. Rb/[(Rc+RL)(Rc+hie)] Av*Ai Hie Hint 49). Which of the following is the formula of circuit power gain of common emitter based BJT amplifier? –hfe/hie[Rc||RL] Hfe. RC. Rb/[(Rc+RL)(Rc+hie)] Av*Ai Hie Hint 50). Which of the following is the formula of circuit input impedance of common emitter based BJT amplifier? –hfe/hie[Rc||RL] Hfe. RC. Rb/[(Rc+RL)(Rc+hie)] Av*Ai Hie Hint BJT Amplifier Important Questions for Interviews 51). At which frequency common emitter based BJT amplifiers voltage drop happens? High Low Mid Both a and b Hint 52). At which frequency common emitter based BJT amplifiers voltage remains constant? High Low Mid Both a and b Hint 53). At which frequency reactance of coupling capacitor in common emitter based BJT amplifiers is high? High Low Mid Zero Hint 54). At which frequency reactance of coupling capacitor in common emitter based BJT amplifiers is small? High Low Mid Zero Hint 55). How much quantity of signal flows through common emitter based BJT amplifiers at low frequency? Small Large Zero Constant Hint 56). At which frequency of common emitter based BJT amplifiers voltage gain decreases? High Low Zero Constant Hint 57). At which frequency of common emitter based BJT amplifiers loading effect increases? High Low Zero Constant Hint 58). At which frequency ‘β’ value of common emitter based BJT amplifiers is minimized? High Low Zero Constant Hint 59). Which of the following is the formula of mid frequency in common emitter based BJT amplifiers? FL-FH FH-FL FH+FL FL+FH Hint 60). At which frequency constant gain of voltage is observed in common emitter based BJT amplifiers? High Low Zero Constant Hint 61). How much quantity of signal is applied to common emitter BJT amplifier? High Low Constant Zero Hint 62). How much quantity of signal is applied to common base BJT amplifier? High Low Constant Zero Hint 63). How much quantity of signal is applied to common collector BJT amplifier? High Low Constant Zero Hint 64). Common emitter based BJT amplifier is ___ class amplifier? Class A Class B Class C Class AB Hint 65). Common base based BJT amplifier is ___ class amplifier? Class A Class B Class C Class AB Hint 66). Common collector based BJT amplifier is mostly used in ___ configuration? Class AB Class B Class C Both a and c Hint 67). Which of the following is the operation frequency of Common Emitter based BJT amplifier? Direct current Audio frequency Radio frequency VHF Hint 68). Which of the following is the operation frequency of Common Base based BJT amplifier? Direct current Audio frequency Radio frequency VHF Hint 69). Which of the following is the operation frequency of Common Collector based BJT amplifier? Direct current Audio frequency Radio frequency All the above Hint 70). Which of the following is the characteristics of common base type amplifier? Gain voltage is high Gain current is low Power gain is low All the above Hint 71). A common base based BJT amplifier has ____ phase? 90 120 180 0 Hint 72). The input impedance of common base based BJT amplifier is ______? High Low Zero Constant Hint 73). Which of the following are the applications of common base based BJT amplifier? Common collector Common base Common emitter All the above Hint 74). Which of the following configuration is called emitter follower? Common collector Common base Common emitter All the above Hint 75). In which of the following component a Darlington type amplifier is used? Common collector Common base Common emitter All the above Hint BJT Amplifier Quiz Questions and Answers. 76). Which of the following is the major function of Darlington amplifier in CE configuration of BJT amplifier ? Boosts input resistance Boosts output resistance Increases conductivity All the above Hint 77). A emitter following circuit has ___ as additional component? Load Capacitor Inductor All the above Hint 78). In emitter follower circuit the out is taken from ___ terminal? Emitter Collector Base Both A and B Hint 79). Which of the following is the input terminal of emitter follower circuit? Emitter Collector Base Both A and B Hint 80). Which of the following is the output voltage of emitter follower? V0=IE * RE V0=Vf Vi=Vs-Vα All the above Hint 81). Which of the following is feedback voltage of emitter follower? V0=IE * RE Vf=V0 Vi=Vs-Vα All the above Hint 82). Which of the following is input voltage of emitter follower?a V0=IE * RE Vf=V0 Vi=Vs-Vα All the above Hint 83). The voltage gain of emitter follower BJT amplifier is ____? 1 <1 >1 0 Hint 84). An unwanted quantity in a signal is called ______? Noise Disturbance Music Both a and b Hint 85). A good electronic system has _____ quantity of noise? High Constant Minimum Zero Hint 86). A BJT amplifier experience ___ types of noise? 2 3 4 5 Hint 87). Which of the following type of noise is observed from BJT amplifiers receiver component? Buzz Flicker Hiss All the above Hint 88). Which of the following is the application of BJT transistor amplifier? Radio signals Long distance communication Amplification devices All the above Hint 89). On which of the following factors class amplifiers are classified? Load Efficiency Input voltage All the above Hint 90). When output of one amplifier is given as input to other amplifier and so on then the amplifier is ___ staged amplifier? 1 2 3 Multi Hint 91). When a circuit has one amplifier then the amplifier is ___ staged amplifier? 1 2 3 Hint 92). An amplifier has ___ number of port? 1 2 3 4 Hint 93). Which of the following is the frequency range of RF amplifier? 20KHz to 300GHz 20KHz to 100GHz 30KHz to 90GHz 45GHZ to 95GHz Hint 94). Which of the following is the frequency range of RF amplifier?94. Which of the following is the frequency range of RF amplifier? 20KHz to 300GHz 20KHz 30KHz to 90GHz 45GHZ to 95GHz Hint 95). Which of the following is the first amplifier designed? Triode Diode Switch All the above Hint 96). Who invented first transistor? Lee De Forest Charles Danial Richard All the above Hint 97). A amplifier with zero feedback is called______? Unilateral Bilateral Trilateral All the above Hint 98). The input based impedance of unilateral amplifier ____ on load? Depends Independents Zero Both a and c Hint 99). A inverting type amplifier has ___phase with input signal? 120 0 180 360 Hint 100). An inverting type amplifier has _____ polarity feedback? Positive Negative Both a and b Neutral Hint Time is Up! Time's up
