Low Noise Amplifier Question & Answers July 8, 2022 By WatElectronics This article lists 50 Low Noise Amplifier (LNA) MCQs for engineering students. All the Low Noise Amplifier (LNA) Questions & Answers below include a hint and a link to the relevant topic wherever possible. This is helpful for users preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of Low Noise Amplifier (LNA). Amplifiers in the communication system enhance the signal's strength and increase the power of noise & signal present in the input. Because of the passive and the active components present the overall noise present in the circuit increases. To overcome such noises Low Noise Amplifier (LNA) concept was introduced. These are the building blocks of Radiofrequency systems. LNA is an Electronic amplifier that amplifies (very) low power signals without any degradation in Signal-Noise ratio (SNR). The designer selects less noisy components, Circuit topologies, and Operating points that minimize the additional noises. The minimized noises should be balanced with further design goals of matching impedance and Power gain. The essential specifications of LNA are Gain, Noise Figure, Linearity, and the max. The input of RF. High amplification at the initial stage of the amplifier results in less noise. This is made possible by selecting transistors like JFETs (Junction Field Effect Transistor) & HEMTs (High Electron Mobility Transistor). 1). What kind of amplifiers can amplify lower strength signals? Power Amplifier (PA) High Power Amplifier (HPA) Low Noise Amplifier (LNA) Large Signal Amplifier None Hint 2). LNA’s are placed at _______? Transmitter end Receiver end Receiver Front End Transmitter Front End None Hint 3). LNA is a ____ amplifier? Class A Class B Class C Class AB None Hint 4). What is the purpose of LNA? Additional Noises Maximized Additional Noises Minimize Degrade Signal-Noise Ratio (SNR) Lower the Power Gain None Hint 5). LNAs must be kept closed to _____? Transmitting Devices Receiving Devices Both Transmitters & Receivers Propagation Devices None Hint 6). __________ is added to the signal received in Low Noise Amplifier (LNA)? Useful Data Useless Data Relevant Information Necessary Information None Hint 7). What in LNA restricts the sensitivity of receivers? Gain Linearity Noise Figure RF Input None Hint 8). What type of models prefer Non-linear Mixing? Small-signal Large-signal Small & Large Signals None None Hint 9). What determines the LNA’s efficiency? Gain Linearity Noise Figure RF Input None Hint 10). LNA must have low______? Gain Linearity Noise Figure RF Input None Hint 11). What should be the required range of Gain? 10-20 dB 20-30 dB 30-40 dB 0-10 dB None Hint 12). What are the various requirements of LNA? Gain 10-20dB Good Linearity Low Noise All Mentioned Above None Hint 13). What should be the sensitivity for LNA? Low Constant High Pre-defined None Hint 14). Why the impedance at source matched to the impedances at input in LNA? Maximize Resistance Transfer Maximize Power Transfer Maximize Capacitance Transfer Maximize Noise Transfer None Hint 15). What topologies for LNA are chosen for low impedance at source? Common Base Common Emitter Common Gate a & c None Hint Low Noise Amplifier LNA MCQs for Interviews 16). What impedances of source use common emitter topology? Low Medium High Constant None Hint 17). What is the appropriate topology if the resistance at source is high in LNA? Common Source Common Base Common Gate Common Drain None Hint 18). What is meant by Source Pulling? Adjusting Admittance of Source Mapping Admittance Characteristics Adjusting Equivalent Noise Factor Adjusting & Mapping Source Admittance None Hint 19). How the topologies are classified in LNA? Wideband LNA Narrow band LNA Band rejection LNA a & b None Hint 20). What are the various architectures of LNA? Resistive Termination Common Gate Shunt Feedback All Mentioned Above None Hint 21). What are the various topologies for LNA Narrow band? Inductive Degenerated Resistive Terminated Common Gate a & b None Hint 22). ________ topology degrades the Noise figure in LNA? Resistive Termination Common Gate Shunt Feedback All Mentioned Above None Hint 23). How the matching is done in LNA’s Resistive shunt-feedback? Applying Positive Feedback Applying Negative Feedback By Placing a Inductor By Placing a Capacitor None Hint 24). Impedance at input behaves as ______ circuit in Inductive Degenerated topology of LNA. Series RLC Parallel RLC Series RL Parallel RL None Hint 25). Which LNA architecture has small Noise figure? Inductive Degenerated Resistive terminated Common Gate Shunt Feedback None Hint 26). What is IP3 in LNA? Third Order Interval Point Third Order Intersection Point Third order Internet Protocol Third Order Inverse Point None Hint 27). What is the need to improve Linearity of LNA? To Improve Receiver Resistance To Improve Transmitter Efficiency To Improve Receiver Sensitivity To Improve Transmitter Sensitivity None Hint 28). What are the popular active devices used in LNA? Ga As SiGe Al P a & b None Hint 29). Which active devices in LNA generates less noise? Ga As SiGe Al P AlGa None Hint 30). What are the advantages of Ga As pHEMT over si Ge? Low Noise Figure High P1dB High OIP3 All Mentioned Above None Hint Low Noise Amplifier LNA MCQs for Exams 31). For what applications Ga As pHEMT is chosen? Sensitive to Power Consumption Very Low Noise Figure Optimizing Sensitivity of Receiver b & c None Hint 32). Why si Ge LNA are preferred? Sensitive to Power Consumption Costly Optimizing Sensitivity of Receiver Low Noise Figure None Hint 33). Dynamic range is limited in _____ LNA? Ga As SiGe Al P AlGa None Hint 34). Why SiGe LNA’s are less costly? Low Noise Figure High P1dB High OIP3 High Integration None Hint 35). SiGe LNA’s are appropriate in _______ applications? Battery-powered High Linearity Low Noise Irrelevant Data None Hint 36). Why the elements are limited in between input of LNA and antenna? To Mitigate NF Degradation To Mitigate Power Degradation To Mitigate Efficiency Degradation To Mitigate Linearity Degradation None Hint 37). Greater the reverse isolation makes a way for _______ in LNA? Easy Impedance Matching Improve Stability Easier to Match Impedance & Improve Stability Iterative Tuning None Hint 38). What is required for less Reverse isolation LNA? Easy Impedance Matching Improve Stability Easier to Match Impedance & Improve Stability Iterative Tuning None Hint 39). What is the major drawback of using Shunt-Feedback topology in LNA? Large Noise Figure Stability Large Area Linearity None Hint 40). Input matching is complex in _______? Inductive Degenerated Resistive terminated Common Gate Shunt Feedback None Hint Low Noise Amplifier LNA MCQs for Quiz 41). Why filters are placed prior to LNA? Attenuate Signals Block Signals Protect from Unwanted Signals Protect from Unwanted & Target signals None Hint 42). Given Conditions are Γ0 = 0.485 angle 155 degree Rn = 6 ohms NFmin= 2 dB,NFi= 4 dB,Zo=50ohms, Ni =0.246. Find the radius RFi? 0.246 0.675 0.482 0.345 None Hint 43). Given Conditions are Γ0 = 0.485 angle 155 degree Rn = 6 ohms NFmin= 2 dB,NFi= 4 dB,Zo=50ohms, Ni =0.246. Find the Noise Figure? 0.246 0.675 0.989 1.735 None Hint 44). In receiver circuit, LNA is placed between ________ & _________? Antenna & Feeder Cable Antenna & Oscillator Mixer & Feeder Cable Antenna & Mixer None Hint 45). Given Conditions are Γ0 = 0.485 angle 155 degree Rn = 6 ohms NFmin= 2 dB,NFi= 4 dB,Zo=50ohms, Ni =0.246. Find the center CFi? 0.246 0.387 0.989 1.735 None Hint 46). What type of amplifier control Feed line losses? Low Noise Amplifiers (LNA) High Power Amplifiers (HPA) Large Signal Amplifier Power Amplifier (PA) None Hint 47). What are the benefits of using LNA? Boosts Power High SNR can be Degraded Min. Interference Loss All Mentioned Above None Hint 48). What enhances the SDR’s performance? Low Noise Amplifiers (LNA) High Power Amplifiers (HPA) Large Signal Amplifier Power Amplifier (PA) None Hint 49). Which amplifier is known as the building or the essential block of Communication systems? Low Noise Amplifiers (LNA) High Power Amplifiers (HPA) Large Signal Amplifier Power Amplifier (PA) None Hint 50). What type amplifier preferred in satellite communications at receiving ground station? Low Noise Amplifiers (LNA) High Power Amplifiers (HPA) Large Signal Amplifier Power Amplifier (PA) None Hint Read More About Low Noise Amplifier LNA Please fill in the comment box below. Time's up
