AD/DA conversion

How many comparisons does an N-bit successive-approximation AD converter basically perform per conversion?

  1. A1
  2. B2ᴺ
  3. CN
Show answer and explanation

Answer: C. N

A successive-approximation ADC starts from the most significant bit and compares whether the input exceeds the internal DAC voltage, deciding one bit per comparison (a binary search). An N-bit conversion therefore basically needs N comparisons.

  • A. Deciding all bits in a single comparison is the idea of the flash type, which uses many comparators.
  • B. 2ᴺ is the count for a method that compares against every level in turn.
  • C. Correct. One comparison per bit, N in total.
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More AD/DA conversion questions

  1. Which correctly describes the acquisition time of a sample-and-hold circuit?
  2. What is the technique of deliberately sampling a signal centered at 70 MHz with a 10 MHz bandwidth at a lower sampling frequency, which also performs frequency conversion?
  3. What is the main purpose of deliberately adding a small noise (dither) before AD conversion?
  4. What is the effect of raising the order of the modulator in a ΔΣ AD converter (for example, from first to second order)?
  5. In a time-interleaved ADC that alternates between several ADCs, what problem is caused by mismatches in offset, gain and timing between the individual ADCs?