Definition and role of an ADC in mixed-signal systems What does an analog-to-digital converter (ADC) do?

Introduction / Context:
An analog-to-digital converter (ADC) bridges the physical world of continuous signals (sound, temperature, voltage) and the digital domain of processors and logic. Mastering what an ADC does is the first step toward understanding sampling, quantization, and data acquisition systems.

Given Data / Assumptions:

• Input is an analog signal (continuous amplitude, often voltage).
• Output is a digital code (binary representation).
• Ideal behavior assumed (no nonlinearity, noise, or jitter for the basic definition).

Concept / Approach:
An ADC samples the input at discrete time intervals and quantizes each sample into one of 2^N levels (for an N-bit converter). The result is a digital word suitable for storage, processing, or transmission. Core specs include resolution (bits), sampling rate, input bandwidth, and effective number of bits (ENOB).

Step-by-Step Solution:

Verification / Alternative check:
Consider a microphone signal digitized by an audio ADC; the digital samples can be processed or stored. Playing back requires the inverse device (DAC) to reconstruct analog waveforms for speakers.

Why Other Options Are Wrong:

• “Makes digital signals” is vague and incomplete.
• “Allows the use of digital signals” is overly general, not a definition.
• “Stores information on a CD” describes storage media, not conversion.

Common Pitfalls:
Confusing ADC with DAC; overlooking that sampling and quantization introduce error (quantization noise), which is part of real-world ADC behavior.

Final Answer:
It takes analog signals and puts them in digital format.