Voltage Controlled Oscillator Question & Answers September 5, 2022 By WatElectronics This article lists 75 Voltage Controlled Oscillator MCQs for engineering students. All the Voltage Controlled Oscillator 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 on the fundamentals of Voltage Controlled Oscillator. Electronic oscillators whose oscillation frequency is dependent upon the applied input voltages are referred to as Voltage Controlled Oscillators. The instantaneous frequency of oscillators is determined by making use of applied voltages at the input. Based on the controlled inputs applied to the modulated signal Voltage Controlled Oscillators are used for Phase or Frequency modulation. Voltage Controlled Oscillators are an essential part of PLLs (Phase Locked Loop). These are also utilized as Synthesizers and their pitch gets adjusted based on determined voltages. There are various forms of Voltage Control Oscillators generally could be RC Oscillators, LC Oscillators, or Crystal. Input voltages and capacitance are inversely in proportion to each other in VCO. An increase in voltage at the input reduces the capacitance whereas the oscillation frequency is in direct proportion to the control voltages. To achieve varying voltages Varactor diodes whose capacitances are variable are used in Voltage Controlled Oscillators. Further, these VCOs are categorized into two types: Harmonic and Relaxation Oscillators. The electronic equipment of jamming, Function Generators, PLLs, and Synthesizers placed in Communication circuits, etc.… are the various applications where VCOs are used. 1). How is oscillation frequency gets controlled in Voltage Controlled Oscillator? Input Voltage Output Voltage Input Current Output Frequency Hint 2). Output frequency of Voltage Control Oscillator is inversely in proportion to _______? Resistance Capacitance Input Voltages a & b Hint Read More About Crystal Oscillators 3). Voltage Control Oscillators frequency is directly in proportion to _________? Resistance Capacitance Input Voltages All Mentioned Above Hint 4). What is VFC? Voltage-Frequency Converter Volume Frequent Converter Voltage Frequent Converter Volume-Frequency Compressor Hint 5). In how many groups, voltage controlled oscillators are categorized? Two Three Four Five Hint 6). What are the various types of voltage controlled oscillators? Harmonic Oscillators Relaxation Oscillators a & b None Hint 7). What type of oscillators generate sinusoidal waves as the outcome? Harmonic Oscillators Relaxation Oscillators a & b None Hint 8). What does a harmonic oscillator consist of? Amplifier Resonator a & b Timer Hint 9). Which one is the Harmonic oscillator? LC Oscillators UJT Oscillator Comparator Multivibrators Hint 10). What are the formulae to calculate obtained frequency at the output in voltage controlled oscillator? fo = (2* (Vcc-Vc))/ (Ct *Rt * Vcc) fo = (2* (Vcc-Vc)) fo = (2* (Vcc-Vc))/ (Ct *Rt ) fo = (2* (Vcc-Vc))/ Vcc Hint 11). Crystal oscillators are ___________? Harmonic Oscillators Relaxation Oscillators Linear Oscillators a & c Hint 12). What type of waveform is produced by Relaxation oscillators? Sine Wave Sawtooth Wave Triangular Wave Triangular or Sawtooth Wave Hint 13). What kind of oscillators are utilized in Integrated Circuits? Harmonic Oscillators Relaxation Oscillators Linear Oscillators a & c Hint 14). What type of oscillators have minimum components externally? Harmonic Oscillators Relaxation Oscillators Linear Oscillators a & c Hint 15). Relaxation oscillators provides wide ranges of ________? Operational Frequencies Resonance Resistance Capacitance Hint 16). What isolates the resonator in Harmonic oscillators? Amplifier Comparator Multivibrator Timer Hint 17). Voltage-Controlled capacitor used in making of ______? LC Oscillators UJT Oscillator Comparator Multivibrators Hint 18). How the frequencies in ring oscillators are controlled? Varying Supply Voltages Current Availability to Each Inverter Capacitive Loading All Mentioned Above Hint 19). What are the prominent characteristics of Voltage Control Oscillators? Tuning Range Tuning Gain Phase Noise All Mentioned Above Hint 20). What is preferred in voltage control oscillators? Low Phase Noise High Phase Noise High Tuning Gain High Noise Hint 21). What effects phase noise in voltage control oscillators? Noise Tuning Gain a & b Jitter Hint 22). What are the various elements that determine Phase noise? Flicker Noise Output Power Level Q-Factor All Mentioned Above Hint 23). What reduces the effects of Flicker noise? Positive Feedback Negative Feedback Q-factor Power Level Hint 24). Flickering noise of low frequencies affect __________ in VCO? Tuning Range Tuning Gain Phase Noise All Mentioned Above Hint 25). In comparison to Fixed frequency oscillators, VCOs have ______ Q-Factor? High Low Moderate Severe Hint Voltage Controlled Oscillator MCQs for Interviews 26). Voltage control oscillators doesn’t have __________? OFF-Chip Components ON-Chip Inductors a & b ON-Chip Capacitors Hint 27). What are the commonly used voltage controlled oscillator circuits? Clapp Oscillators Colpitts Oscillators Crystal Oscillators a & b Hint 28). What is the purpose of a voltage-controlled crystal oscillator? Adjust Operating Frequency Controls Voltage Controls Temperature Generate Timing Signals Hint 29). What is the purpose of the voltage control crystal oscillator clock generator? Adjust Operating Frequency Controls Voltage Controls Temperature Generate Timing Signals Hint 30). What are the design parameters of the voltage control crystal oscillator clock generator? Tuning Voltage Range Center Frequency Frequency Tuning Range All Mentioned Above Hint Read More About UJT Relaxation Oscillator 31). What is the equation to calculate the time period of the voltage controlled oscillator? T= 2*∆t T = (Vcc * CT)/ 2i T = (Vcc * CT) a & b Hint 32). Determine the flow of current in Voltage Control Oscillators. For NE566 resistor connected externally i.e., RT is 200 ohms and voltage at input is 2.5 Volts (Consider VCC= + 5Volts). 13 m A 12.5 mA 7 mA 0 mA Hint 33). What is the frequency at output if there is no voltage signal applied at the input? 1/(4*RT*CT) 1/(4* RT) 1/(4*CT) 1/(6*RT*CT) Hint 34). Calculate the capacitor value connected externally for no input voltage applied to Voltage Control Oscillator. For Output frequency, 20 kHz & RT is 5 K ohms. 10 nF 5 n F 2.5 nF 2 nF Hint 35). What is the maximum frequency at the output for NE566? 100 kHz 250 kHz 500 kHz 1000 kHz Hint 36). Which of these voltage control oscillators have the highest frequency at the output? SE566 NE566 MC4024 All Mentioned Above Hint 37). What is meant by Voltage to Frequency Conversion Factor? Change in Frequency to Change in Modulating Input Voltage Change in Resistance to Change in Modulating Input Voltage Change in Capacitance to Change in Modulating Input Voltage Change in Frequency to Change in Output Voltage Hint 38). Calculate Kv of the Voltage Control Oscillator if fo is 150Hz & VCC is 10 Volts. 130 120 110 100 Hint 39). What is the equation of frequency changing in the voltage controlled oscillator? fo = (2* (Vcc-Vc))/ (Ct *Rt * Vcc) fo = (2* (Vcc-Vc)) fo = (2* (Vcc-Vc))/ (Ct *Rt ) ∆fo = (2*∆ Vc)/ (Ct *Rt * Vcc) Hint 40). Calculate the resistor value connected externally for no input voltage applied to Voltage Control Oscillator. For Output frequency 20 kHz & CT is 2.5 nF. 5 Kohms 10 Kohms 15 Kohms 20 Kohms Hint 41). What various forms of VCO are obtained? Discrete Modular Monolithic All Mentioned Above Hint 42). Which form of VCO offers maximum flexibility in terms of design? Discrete Modular Monolithic All Mentioned Above Hint 43). How is frequency controlled is achieved in VCO? Using Varactor Diodes Using Timers Using Counters Using Multiplexers Hint 44). _________ determines the Tuning range of voltage controlled oscillator? Resistance Range of Varactor Diode Capacitance Range of Varactor Diode Load Variations Required Feedback Hint 45). Selection of BJT and varactor in VCO is based on ________? Oscillator Frequency Capacitance Range of Varactor Diode Load Variations Required Feedback Hint 46). How the Voltage Control of the Oscillator can be realized? Adding Varactor Parallel with Tank Circuit Adding Varactor Series with Tank Circuit Load Variations Feedback Applied Hint 47). Which form of VCO takes up more area of PCB? Discrete Modular Monolithic All Mentioned Above Hint 48). Input tuned voltage corresponding to voltage swings at input in ________? Voltage Control Oscillator Timer Multiplexer Demultiplexer Hint 49). What is the indicator of VCO’s purity of signals? Oscillator Frequency Specification Capacitance Range of Varactor Diode Load Variations Phase Noise Specifications Hint 50). What broadens spectral response in VCO? Tuning Range Tuning Gain Phase Noise All Mentioned Above Hint Voltage Controlled Oscillators MCQs for Exams 51). Why is the Phase noise incurred in VCO? Thermal Noise Other Noise Sources a & b Frequency Spectrum Hint 52). Phase Noise in ________leads to Timing jitter? Frequency Domain Time Domain a & b None Hint 53). What is TIE in VCO? Noise Tuning Gain a & b Jitter Hint 54). What represents the upcoming high level of Integration of circuits? Discrete Modular Monolithic All Mentioned Above Hint 55). What form of VCO can be used as a component? Discrete Modular Monolithic All Mentioned Above Hint 56). In what ranges Modular VCOs are available? Output Frequency Tuning Range Output Power Levels All Mentioned Above Hint 57). What form of VCO provides the highest density of volume? Discrete Modular Monolithic All Mentioned Above Hint 58). MAX2623 is a ______ form of VCO? Discrete Modular Monolithic All Mentioned Above Hint 59). What are the examples of Monolithic VCOs? MAX2623 HMC512LP5ETR NE566 a & b Hint 60). What does a MAX2623 consist of? Self-contained VCO Integrated Oscillator Output Buffer All Mentioned Above Hint 61). How many pins does a Maxim Integrated (MAX2623) VCO have? 6 Pins 8 Pins 12 Pins 18 Pins Hint 62). HMC512LP5ETR VCO is used in _______? Satellite Communications Multipoint Radio Military Applications All Mentioned Above Hint 63). Basic VCO circuits are built using _______? Resistors Inductors Capacitors a, b & c Hint 64). What are the various voltage controlled oscillators? Emitter Coupled Collector Coupled Grounded Capacitor a & c Hint 65). LM566 VCO can generate _________ waves? Sine Wave Sawtooth Wave Triangular Wave b & c Hint 66). What is the mainly focused parameter of VCO? Jitter Frequency Gain Sweeping Time Hint 67). Frequency hopping applications use ____________? Voltage Control Oscillator Timer Multiplexer Demultiplexer Hint 68). What are the various applications of voltage control oscillators? Communication Systems RADAR PLLs All Mentioned Above Hint 69). What converts lower frequency signals to Audio range of frequencies? Voltage Control Oscillator Timer Multiplexer Demultiplexer Hint 70). What device is utilized in diagnostics and recording? Voltage Control Oscillator Phase Locked Loop Multiplexer Filter Hint 71). How the output frequencies in voltage controlled oscillators are changed? Resistors Capacitors Input Voltages All Mentioned Above Hint 72). Voltage controlled oscillators are used in ______? Frequency Modulation Frequency-shift Keying a & b Phase Modulation Hint 73). What are the various applications of Voltage Control Crystal Oscillator Clock Generator? Digital TV Modems Computers & Transmitters All Mentioned Above Hint 74). High frequency voltage controlled oscillators are used in _______? Voltage Control Oscillator Phase Locked Loop Multiplexer Filter Hint 75). Monolithic Function Generators are _________? Current-Controlled Voltage Controlled Temperature Controlled All Mentioned Above Hint For More MCQs Oscillators Question & Answers RC Phase Shift Oscillator Question & Answers Hartley Oscillator Question & Answers Colpitts Oscillator Question & Answers Wien Bridge Oscillator Question & Answers Please fill in the comment box below. Time's up