Signal processingLesson 3 of 3 in the course Sampling

ADC Conversion: Resolution, Sampling, Errors, and Architectures

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

An analog-to-digital converter (ADC) makes continuously varying real-world signals usable by digital systems. This lesson introduces the conversion process, common ADC outputs, and the meaning of resolution.

An analog signal varies continuously in time and amplitude. A microphone produces a voltage that follows sound pressure; a camera sensor responds to light; and a touchscreen can produce signals related to a finger's position. An ADC measures such an input and represents it as a sequence of digital values.

All flashcards

What is an analog-to-digital converter (ADC)?
A converter that samples an analog input and represents its measurements as digital codes.
What does a digital-to-analog converter (DAC) do?
It converts digital values into an analog signal.
How many codes can an MM-bit ADC represent?
It can represent 2M2^M distinct codes.
What is the nominal voltage resolution of a typical ADC?
The input-voltage change per quantization interval, often Q=EFSR/2MQ=E_{FSR}/2^M.
What does effective number of bits (ENOB) describe?
The practical bit resolution that reflects how noise and other imperfections limit useful measurements.

Quiz questions

  1. What can happen when an input signal contains frequencies above half the ADC sampling rate?Answer: Those components can appear as lower frequencies in the sampled data.
  2. How does a successive-approximation (SAR) ADC determine an input code?Answer: It uses successive midpoint tests, resolving one bit per comparison cycle.
  3. What is a typical purpose of adding dither before ADC quantization?Answer: To reduce signal-correlated quantization distortion by adding controlled randomness.
  4. How does a dual-slope integrating ADC obtain a measurement?Answer: It integrates the input for a fixed time, then measures the reference-driven return time to zero.
  5. With MM time-interleaved ADCs, what is the ideal combined sampling rate relative to one converter’s rate?Answer: MM times the rate of one converter.

Based on the Wikipedia article Analog-to-digital converter, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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