Practical Electronics Circuits Flashcards

What is the primary purpose of a bypass capacitor placed near an IC power supply pin?

Answer: To filter high-frequency noise from the supply rail

Bypass capacitors filter high-frequency noise on the power supply rail, preventing it from coupling into sensitive IC circuitry.

Which configuration of a bipolar junction transistor (BJT) provides both voltage and current gain?

Answer: Common emitter

The common-emitter configuration provides both voltage gain and current gain, making it the most widely used amplifier topology.

In a Class AB amplifier, what problem does the small forward bias on the output transistors solve?

Answer: Crossover distortion present in Class B amplifiers

A small forward bias keeps the output transistors just at the edge of conduction, eliminating the dead-zone crossover distortion of Class B.

What does the slew rate of an operational amplifier specify?

Answer: The maximum rate of change of the output voltage in V/µs

Slew rate is the maximum speed at which an op-amp's output voltage can change, expressed in volts per microsecond.

A Zener diode is used in reverse breakdown primarily to:

Answer: Provide a stable reference voltage

Zener diodes are designed to operate in reverse breakdown, maintaining a nearly constant voltage across their terminals for regulation or reference use.

What type of feedback is used in a voltage-regulator op-amp circuit where the output is sampled and returned to the inverting input?

Answer: Negative voltage feedback

Sampling the output voltage and feeding it back to the inverting input is classic negative voltage feedback, which stabilizes the output.

Which component in a switching power supply controls the duty cycle to regulate output voltage?

Answer: The PWM controller IC

The PWM (pulse-width modulation) controller IC compares the output voltage to a reference and adjusts the duty cycle of the switching transistor accordingly.