Channel multiplexing – when several analog sources must be digitized, can a single ADC be time-shared via an analog multiplexer that selects one input at a time for conversion?

Introduction / Context: Many embedded systems must digitize multiple sensor channels but can afford only one ADC due to cost or space. A standard approach is to time-division multiplex channels using an analog multiplexer (MUX) and a sample-and-hold or track-and-hold front end as needed for accuracy and speed.

Given Data / Assumptions:

• ADC has adequate sampling rate to service all channels within required update times.
• An analog MUX selects which sensor connects to the ADC input.
• Settling and source impedance are compatible with ADC input requirements.

Concept / Approach: Time-sharing a single ADC works by cycling through inputs: select channel i, allow settling and hold if necessary, start conversion, read result, then proceed to channel i+1. Provided the ADC's throughput meets the sum of per-channel rates and the analog front end is designed for proper settling and isolation, one ADC can serve many sources effectively.

Step-by-Step Solution:

Verification / Alternative check: Microcontrollers with built-in ADCs commonly expose multiple channels through an internal MUX; discrete designs replicate this externally with 74HC4051-class devices or instrumentation multiplexers.

Why Other Options Are Wrong: Current-mode only is false; strict 1 mV ground match is unnecessarily tight (use proper grounding/guarding). A dedicated S/H per channel is optional, not always required.

Common Pitfalls: Insufficient settling time, high source impedance causing gain errors, and crosstalk between channels if MUX isolation is poor.

Final Answer: Correct