BEE Bachelor of Electrical Engineering Analog and Digital Electronics Questions and Answers Flashcards

What is the primary advantage of using CMOS logic over TTL logic in digital circuits?

Answer: Lower static power consumption

CMOS logic consumes negligible static power because one of the complementary transistors is always off, drawing almost zero current in steady state.

In a common-emitter amplifier, what is the effect of adding an unbypassed emitter resistor?

Answer: Decreases voltage gain and increases input impedance

An unbypassed emitter resistor introduces negative feedback, which reduces voltage gain but increases input impedance and improves stability.

Which flip-flop is commonly used to eliminate metastability issues in clock domain crossing designs?

Answer: Two-stage synchronizer using D flip-flops

A two-stage synchronizer with back-to-back D flip-flops allows the potentially metastable output of the first stage to settle before being sampled by the second.

What does the Barkhausen criterion state for sustained oscillation in a feedback circuit?

Answer: Loop gain must equal unity and total phase shift must be a multiple of 360 degrees

The Barkhausen criterion requires the loop gain magnitude to be exactly one and the total phase shift around the loop to be 0° or a multiple of 360° for sustained oscillations.

In a 4-bit binary weighted DAC with a reference voltage of 10V, what is the resolution (smallest voltage step)?

Answer: 0.625 V

Resolution equals Vref divided by 2^n, so 10V / 16 = 0.625V for a 4-bit DAC.

What is the purpose of a Schmitt trigger in digital circuits?

Answer: To convert analog signals to digital with hysteresis for noise immunity

A Schmitt trigger uses hysteresis with two different threshold voltages to provide clean digital output from noisy or slowly changing input signals.