CET Digital Electronics and Systems 3 — Questions and Answers
Question 1: Which type of ADC offers the fastest conversion speed?
- Dual-slope
- Successive approximation
- Flash (parallel) (Correct answer)
- Sigma-delta
Correct answer: Flash (parallel)
A flash ADC uses a bank of 2^n–1 comparators to convert all bits simultaneously in a single step, making it the fastest architecture.
Question 2: What is the resolution of an 8-bit DAC with a full-scale output of 5 V?
- 5 mV
- 19.53 mV (Correct answer)
- 39.06 mV
- 78.13 mV
Correct answer: 19.53 mV
Resolution = Vfs / (2^n) = 5 V / 256 ≈ 19.53 mV per LSB step.
Question 3: In a synchronous counter, what is the main advantage over a ripple (asynchronous) counter?
- Uses fewer flip-flops
- All flip-flops clock simultaneously, eliminating ripple delays (Correct answer)
- Lower power consumption
- Simpler decoder logic
Correct answer: All flip-flops clock simultaneously, eliminating ripple delays
Synchronous counters clock all flip-flops at the same time, so there is no cumulative propagation delay that causes counting glitches.
Question 4: A Karnaugh map is primarily used to:
- Convert decimal to binary
- Minimize Boolean expressions (Correct answer)
- Generate clock signals
- Design analog filters
Correct answer: Minimize Boolean expressions
A Karnaugh map (K-map) is a graphical method for simplifying Boolean algebra expressions to minimize gate count.
Question 5: Which number system uses 16 as its base and employs the digits 0–9 and letters A–F?
- Octal
- Binary
- Hexadecimal (Correct answer)
- BCD
Correct answer: Hexadecimal
Hexadecimal (base-16) uses 0–9 and A–F to represent values 0–15, commonly used to express binary data compactly.
Question 6: What is the output of a D flip-flop on the rising clock edge when D=0 and the current output Q=1?
- Q remains 1
- Q goes to 0 (Correct answer)
- Q toggles to 0 then back to 1
- Output is undefined
Correct answer: Q goes to 0
A D flip-flop copies the D input to Q on the active clock edge, so D=0 forces Q to 0 regardless of the previous state.
Question 7: In digital communication, what does the term 'baud rate' specifically refer to?
- Bits per second
- Bytes per second
- Number of signal state changes per second (Correct answer)
- Number of errors per second
Correct answer: Number of signal state changes per second
Baud rate is the number of symbol (signal state) changes per second, which equals bit rate only when each symbol represents one bit.
CET Digital Electronics and Systems 3
Which type of ADC offers the fastest conversion speed?