Multiple Choice Questions 1.A(n) _________ generates a waveform by converting direct-current energy to an alternating current. A.amplifier B.synthesizer C.oscillator D.feedback loop 2.Which of the following is an advantage of mechanical filters? A. New technology B. Extreme flexibility C. Excellent rejection characteristics D. Compatible with larger equipment 3.What type of filter is commonly used in single-sideband systems to attenuate the unwanted sideband? A.Crystal B.Bandpass C.Mechanical D.Constant- k 4.Which of the following criteria would help you to choose the oscillator type for use in electronic circuits? A.Input frequency required B. Frequency stability required C. Range of frequency output D. Allowable waveforms 5.Amplifiers are classified by the amount of time during each input cycle that the active device within the circuit conducts __________. A.harmonic content B.pulse-width modulation C.high linearity D.current 6.Why are virtually all oscillators used in communications applications the feedback type? A.They are capable of producing highly pure sine waves. B.The currents in the diodes and the currents in the transistors are the same. C.They use RC timing circuits to generate nonsinusoidal waveforms. D.They allow waveform distortion. 7.The disadvantages of DDS include the limit on maximum output frequency andhigher ___________. A.cost B.output waveforms C.phase noise D.analog units 8.Synthesizers are found in any device that must operate over a range of frequencies. Which of the following is an example of such a device? A. Resonant tank circuits B. Cellular phones C. Rotary dial phones D. Landline phones 9.What is the purpose of a balanced modulator? A. To produce an output frequencythat varies in response to changes in a control voltage. B. To change frequency in response to a DC control voltage applied toit. C. To allow a range of frequencies to be generated from a stable, single-frequencyreference. D. To suppress the carrier, leaving only thetwo sidebands. 10.A__________ is where the currents in the diodesand the currents in the transistors are the same. A.current mirror B.push-pull C.cutoff D.conduction angle 1