Class D Amplifier Question & Answers July 30, 2022 By WatElectronics This article lists 100 Class D Amplifier MCQs for Engineering Students. The Class D Amplifier Questions & Answers below include solutions and links to the relevant topic. This is helpful for users who are preparing for their exams and interviews, or professionals who would like to brush up on the fundamentals of Class D Amplifier. Amplifiers to drive the connected loads and tolerates large currents by amplifying or enhancing the power signal strength are referred to as Power Amplifiers. These are connected at the final stages of the chain. To make it operate the applied input must be above the threshold. Based on the output obtained and the characteristics these amplifiers are classified into various classes. They are: Class A, Class B, Class C, Class AB, Class D, Class E, Class F, and so on. Further, these amplifiers are divided into two groups based on the output obtained. Firstly, linear amplifiers are class A, Class B, Class C, and Class AB. The second group i.e., Class D, Class E, class F, and so on are referred to as Switching amplifiers. It provides Non-linear Switching. Class D amplifier functions by taking two-state or binary signals from the control signal i.e., continuous, and amplifying it by using Power switches. This amplifier is highly efficient compared to linear ones. Name Email 1). ________ is referred to as Switching Amplifier? Class A Class AB Class C Class D None Hint 2). Active devices in Class D amplifier are _______? Transistors Resistors Capacitors Inductors None Hint 3). What will be the current in the class D amplifier if the transistor is switched OFF? 0 1m A 1 A 2 A None Hint 4). Power dissipated in class D amplifiers is ___? High Low Severe Moderate None Hint 5). Heat sinks placed in Class D amplifiers are ___? Bulky Small Large Not Needed None Hint 6). How efficient are class D amplifiers? 50% 78% 88% 100% None Hint 7). What are the basic requirements of class D amplifiers? Comparator Switching Power Stage Filter All Mentioned Above None Hint 8). Class D amplifiers have the angle of conduction ___? 0 90 180 270 None Hint 9). _____ operates from deriving a signal consisting of two states? Class A Class AB Class C Class D None Hint 10). ______ takes analog i/p signal and generates PWM wave? Class A Class AB Class C Class D None Hint 11). What type of filter is required in class D amplifiers? Low Pass Filter High Pass Filter Band Stop Filter Band Rejection Filter None Hint 12). Why do class D amplifiers use advanced techniques of modulation? Eliminate External Filtering Reduce Electromagnetic Interference a & b Increase efficiency None Hint 13). Eliminating filters connected externally paves the way for _______ in class D amplifiers? Reduced Board-space Reduces the Cost Increases the Cost a & b None Hint 14). What are the disadvantages of class AB compared to class D? Power Loss by Biasing Elements Power Loss by Output Transistors a & b Cross Over Distortion None Hint 15). What is required in class D to attenuate noise? Comparator Switching Power Stage Low Pass Filter All Mentioned Above None Hint 16). The losses in the output of class D are based on _______? Applied Input Switching Stages Device Parameters a & b None Hint 17). What are the topologies of class D? Half Bridge Full Bridge Wein Bridge a & b None Hint 18). Half bridge of Class D is _______ than Full bridge? Simple Complex Similar Complicated None Hint 19). Which topology of class D is preferred for audio performances? Half Bridge Full Bridge Wein Bridge a & b None Hint 20). Two Half-bridge amplifiers combined with the other components to form __________? Class B Full Bridge Wein Bridge Class AB None Hint 21). Which topology of class D makes better usage of the PWM scheme? Half Bridge Full Bridge Wein Bridge a & b None Hint 22). Non-linearity in PWM of class D amplifier is because of _____? Limited Resolution Timing jitter a & b PWM is Linear None Hint 23). What are the timing errors included in class D amplifiers? Dead-time Time ON/OFF Time Reverse/Forward All Mentioned Above None Hint 24). What are the imperfections caused due to distorted waves generated from class D? Non-linearity in PWM Timing errors Non-linearity in LPF a, b & c None Hint 25). What are the essentials of a Half Bridge Class D amplifier? Pulse Width Modulator Two MOSFETs Low Pass Filter All Mentioned Above None Hint Class D Amplifier MCQs for Quiz 26). ______ operates as Current Steering Switches in Half Bridge Class D amplifier? Pulse Width Modulator MOSFETs Low Pass Filter All Mentioned Above None Hint 27). What are the downfalls of the Half Bridge Class D amplifier? Very Low Power Supply Rejection Ratio High Total Harmonic Distortion a & b Low Total Harmonic Distortion None Hint 28). The outputs quality in the Half Bridge Class D amplifier is dependent on ________? Triangular Wave Linearity Triangular Wave Stability Audio Signal Applied a & b None Hint 29). Open-loop Band width is equivalent to frequency of switching in _______? Class A Class B Class D Self-oscillation Class D None Hint 30). What happens in Class D amplifiers if the loop bandwidth is increased? Provided Valuable Loop Gain Reduced Total Harmonic Distortion Increased Total Harmonic Distortion a &b None Hint Read More about Class D Amplifier None 31). In how many ways Class D amplifiers (self-oscillating) are designed? Hysteresis Switching Phase-shift Controlled Oscillation Phase-shift Control using Reconstruction Filter All Mentioned Above None Hint 32). Gain in class D amplifiers is ________? Constant Varying Fixed Doesn’t Change None Hint 33). What is the Power Supply Rejection Ratio of Class D? 0 dB 10 dB 20 dB 40 dB None Hint 34). What is used in class D to overcome variations of bus voltages? Resistor Capacitor Modulator Feedback None Hint 35). What is the Power Supply Rejection Ratio of Linear amplifiers? 0dB Good Worst Undetermined None Hint 36). How is the energy flow in Full bridge class D amplifiers? Constant Uni-directional Bi-directional b & c None Hint 37). How is the energy flow in Half-bridge class D amplifiers? Constant Uni-directional Bi-directional Can’t Determine None Hint 38). Bus pumping occurs in _____? Class AB Half Bridge Class D Full Bridge Class D Class B None Hint 39). Bus pumping causes _____ to get charged? Bus Capacitors Bus Inductors Battery All Mentioned Above None Hint 40). Bus pumping usually occurs at ______? Low Audio Frequencies High Radio Frequencies High Audio Frequencies Low Radio Frequencies None Hint 41). Reference signal in Class D is ______? Continuously Changing Fixed Change is not Continuous None None Hint 42). Duty cycle in class D is ______? Continuously Changing Fixed Change is not Continuous None None Hint 43). What are the differences between Synchronous Buck Converter & Class D amplifier? Reference signal is changing continuously in class D Duty cycle changing in class D Load Current Direction is Unidirectional in class D a & b None Hint 44). Class D amplifier contains _______ for both MOSFETs? Same Optimization Different Optimization Longer Duty Shorter Duty None Hint 45). Dead time in class D leads to _____? Longer Duty Shorter Duty Total Harmonic Distortion Power Dissipation None Hint 46). What are the different regions in class D? Output Current Flowing from Class D to Load Output Current Flowing from Load to Class D Output Independent of Dead Time All Mentioned Above None Hint 47). What happens in the middle region of class D? Low Side Gate Signal High Side Gate Signal Turn-OFF Edge No Operation Performed None Hint 48). ZVS is _____________? Zero Voltage Switching Zero Voltage Sensing Zero Volume Sensing Zero Volume Switching None Hint 49). Outcome timing in middle region is _________ of dead time. Dependent Independent Constant Negotiable None Hint 50). Is there any distortion in the middle area of operation in class D? Yes No Minimum Maximum None Hint Class D Amplifier MCQs for Exams 51). Reliability is achieved in class D if the dead time is ____? Positive Negative Zero a & b None Hint 52). MOSFETS in class D enters shoot-through condition if dead time is ___. Positive Negative Zero a & b None Hint 53). What type of active device used is advantageous in Class D? BJT FET MOSFET UJT None Hint 54). MOSFET consist of _______? Infinite Gain Less Stable Bulky Dissipates Less Heat None Hint 55). MOSFET in class D leads to _____? Infinite Gain Less Stable Bulky Reduce Cost None Hint 56). IR Digital MOSFETs are designed for ______? Class A Class B Class C Class D None Hint 57). How does the saw-tooth wave gets mixed with applied input? Comparator Switching Power Stage Low Pass Filter All Mentioned Above None Hint 58). What should be the frequency of the saw-tooth wave? 10*Maximum Input Signal Frequency 20*Maximum Input Signal Frequency Maximum Input Signal Frequency None None Hint 59). What represents digitized audio signals in a comparator of class D? Low Frequency Components High Frequency Components Mixed Frequency Components a & b None Hint 60). What is the purpose of the Switching circuit in class D amplifiers? Provide Current Gain Provide Voltage Gain a & b Degrade the Gain None Hint 61). Low pass filter (LPF) in class D purpose is to filter ________? Low Frequency Components High Frequency Components Mixed Frequency Components a & b None Hint 62). What feedback in class D was utilized to make it error-free? Positive Negative Not needed Positive & Negative None Hint 63). How the feedback loop is inserted at the output stages of class D amplifiers? Using Integrator Using Differentiator Using Multiplexer Using Demultiplexer None Hint 64). How the filter is included in the feedback of class D? Using Integrator Using Differentiator Using Multiplexer Using PID Controller None Hint 65). Feedback in class D controls ______? Output Frequency Input Frequency Input Impedance Output Impedance None Hint 66). How do the transistors of class D power amplifier act? Integrator Multiplexer Controlled Switches PID Controller None Hint 67). What is the major drawback of class D power amplifier (Traditional)? Integrator Feedback Control Switch LC Filter None Hint 68). Which topology of class D is preferred when the power is high? Half Bridge Full Bridge Wein Bridge a & b None Hint 69). What is BTL? Bridge-Tied Load Base-Tied Load Bridge-Transistor Load Base-Transistor Load None Hint 70). Alternate conduction establishes a path through Load in ______ topology? Half Bridge Full Bridge Wein Bridge a & b None Hint 71). DC Blocking Capacitor is not essential in _______? Half Bridge Full Bridge Wein Bridge a & b None Hint 72). What is the disadvantage of not connecting an external filter? Increased Noise Decreased Frequency Radiating Electro Magnetic Interference (EMI) Decreased Impedance None Hint 73). To achieve maximum output power speaker load must be _________? Capacitive Inductive Resistive None None Hint 74). How EMI is minimized in class D amplifiers? Frequency Modulation Amplitude Modulation Phase Modulation Spread-spectrum Modulation None Hint 75). What Spread-spectrum modulation does to minimize EMI? Total Energy Distributed at Output Spreading Energy Redistribution of Total Energy at Wide Bandwidth a& b None Hint Class D Amplifier MCQs for Students 76). Modern class D inhibits all the advantages of _________? Class A Class B Class C Class AB None Hint 77). Automotive sound systems use ________ amplifiers? Class A Class B Class C Class D None Hint 78). What are the Low Power Portable Applications of Class D? Preserve Battery Life Board-space Requirements Minimize EMI All Mentioned Above None Hint 79). Flat Panel Display uses ______ amplifiers? Class A Class B Class C Class D None Hint 80). Class D amplifiers output stage is utilized as _______? Modulator Demodulator De-multiplexer Pulse Generator None Hint 81). What is the transition time required by the states of class D amplifier? Infinite Unlimited 10 ns 0 None Hint 82). What are the characteristics (ideal) of Class D amplifiers? Efficiency is 100% THD is 0% No Audible Noise All Mentioned Above None Hint 83). Dead time in class D is proportional to ______? Efficiency THD Audible Noise All Mentioned Above None Hint 84). Switching and Conduction losses are minimized by using ______. BJT FET MOSFET UJT None Hint 85). What should be the die size in the class D amplifier? Increased Decreased Optimal Varying None Hint 86). IRF6645 Class D suits for? 10 W 100 W 200 W 500 W None Hint 87). Power supply must be ________ in Class D amplifiers? Stable Unstable Increased Reduced None Hint 88). High Response of frequency in class D is ________ on Loudspeaker impedance? Dependent Independent Constant Doesn’t Alter None Hint 89). What is the basic difference between class D and other linear classes? Input Applied Temperature Efficiency Power None Hint 90). Why class D amplifiers are advantageous? Less Power Consumption Low Heat Generated Smaller in Size All Mentioned Above None Hint 91). What is the drawback of class D amplifiers? Less Power Consumption Low Heat Generated Smaller in Size High Frequency Generated Noise None Hint 92). Sound Reinforce system makes use of _____ amplifiers? Class A Class B Class AB Class D None Hint 93). What are Car Class D Amplifiers? Radio Frequency Amplifiers Audio Power Amplifiers Voltage Amplifiers Current Amplifiers None Hint 94). What type of amplifiers are used in mobile phones? Class A Class B Class AB Class D None Hint 95). What are the applications of Class D amplifiers? Bass Amplifiers Switch Torch Metal Detection None Hint 96). Home Theater systems use _____ Amplifiers? Class A Class B Class AB Class D None Hint 97). Class D for Subwoofer is ______? Fast Suitable Slow Too Slow None Hint 98). Class D Power Amplifiers of Linn’s Proprietary provides _______? Low Noise Less Distortion Efficient Conversion of Signals All Mentioned Above None Hint 99). Hearing aids have ______ amplifier? Class A Class AB Class C Class D None Hint 100). _______ amplifiers are utilized in high power implementations? Class A Class AB Class C Class D None Hint For More MCQs Low Noise Amplifier Question & Answers Cascode Amplifier Question & Answers Positive Feedback Amplifier Question & Answers Please fill in the comment box below. Time's up
