Dive into five thought-provoking analog electronics questions, crafted to deepen your understanding of concepts like operational amplifiers, filters, biasing, waveform analysis, and signal modulation. This quiz challenges your grasp of analog circuit theory, making it ideal for students and enthusiasts seeking to reinforce their analog electronics knowledge.
In a classic inverting amplifier configuration using an ideal operational amplifier, what effect does increasing the value of the feedback resistor have on the voltage gain?
Explanation: The voltage gain of an inverting amplifier is given by the negative ratio of the feedback resistor to the input resistor. If the feedback resistor increases while the input resistor stays constant, the magnitude of the gain increases. Reducing the feedback resistor would decrease the gain (the second option). Stating 'no effect' is incorrect as the feedback resistor directly influences gain. The phase reversal is always 180 degrees in an inverting amplifier, regardless of resistor values.
Which circuit type can be used to convert a sinusoidal signal into a square wave for use in timing applications?
Explanation: A Schmitt trigger is a comparator circuit with hysteresis that converts a noisy or slowly varying input, such as a sine wave, into a square wave, making it useful in timing and digital applications. Differentiators produce pulses instead of a sustained square waveform. Integrators transform square waves into triangular waves, not the other way around. Active low-pass filters remove high-frequency components and cannot produce square waves from sinusoidal signals.
If an analog signal in an RC low-pass filter circuit is subjected to a frequency much higher than its cutoff frequency, what will be the effect on the output amplitude?
Explanation: An RC low-pass filter attenuates signals with frequencies higher than its cutoff, causing the output amplitude to decrease rapidly beyond the cutoff frequency. The output does not increase at higher frequencies, contrary to the second option. It does not remain constant at all frequencies, as stated in the third option. While attenuation is strong, it will not instantly reduce the signal to exactly zero, making the last option incorrect.
In a common-emitter BJT amplifier, what is the main purpose of the emitter bypass capacitor placed parallel to the emitter resistor?
Explanation: The emitter bypass capacitor provides a low impedance path for AC signals around the emitter resistor, effectively increasing the AC voltage gain by minimizing negative feedback for alternating currents. The second option is incorrect because stabilization of the DC operating point is achieved mainly by the emitter resistor itself, not the bypass capacitor. The third option is inaccurate since the amplifier is designed primarily for amplifying AC signals, and DC is not amplified via bypassing. The fourth option incorrectly states the effect of the capacitor, which actually enhances the AC response rather than blocking it.
Which type of amplitude modulation adds the carrier’s frequency to and subtracts it from the signal’s frequency, resulting in the creation of upper and lower sidebands?
Explanation: Double-sideband amplitude modulation (DSB-AM) produces both upper and lower sidebands at frequencies equal to the sum and difference of the carrier and modulating signal frequencies. Frequency-shift keying changes the frequency of the carrier in response to digital input, not creating symmetric sidebands. Phase modulation varies the phase of the carrier according to the message signal. Pulse-width modulation changes the duty cycle of pulses without producing upper and lower sidebands related to the carrier.