Maintaining a sampled signal level between samples Which term describes holding the analog value constant until the next sampling instant in data acquisition systems?

Introduction / Context:
In sample-and-hold (S/H) circuits used ahead of many ADCs, the analog input is sampled at a specific instant and then maintained for a finite time while conversion occurs. This avoids input slewing during conversion and improves accuracy for fast-changing signals.

Given Data / Assumptions:

• The system includes a sample-and-hold element.
• After sampling, the held value must remain stable until the next sample or until the ADC completes conversion.
• Terminology focuses on the behavior between samples.

Concept / Approach:

“Holding” is the action by which the S/H circuit maintains the captured voltage. The resulting analog output of a zero-order hold looks like a staircase when viewed over time, but the act itself is holding. Aliasing refers to spectral foldover from under-sampling and “Shannon frequency” (Nyquist rate) is a sampling theorem concept, not the name of the hold action.

Step-by-Step Solution:

Verification / Alternative check:

Observe with an oscilloscope: the S/H output is flat during hold intervals, then updates at each sample—classic stepwise behavior.

Why Other Options Are Wrong:

Aliasing is a frequency-domain artifact; “Shannon frequency sampling” refers to a theoretical minimum sampling rate; “stair-stepping” is a visual description of the waveform, not the process term.

Common Pitfalls:

Confusing the staircase appearance with the functional block name; overlooking hold droop errors due to leakage and finite input impedance of buffer/ADC.

Final Answer:

Holding