Sensors and ADC Resolution

Electronics and Embedded Systems · CHAPTER 2 / 5

Level: introductory undergraduate · Study session: 15–20 minutes including practice.

Learning outcome: Map analogue voltage to an ideal digital code.

Before you begin: Complete earlier chapters in this discipline; revise algebra and units as needed.

1. Understand the idea

An analogue-to-digital converter quantises a voltage relative to a reference. More bits create more code levels, but accuracy also depends on reference error, noise, sensor calibration and input circuitry. Resolution is not the same as measurement accuracy.

2. Write the model

Code ≈ round[(Vin/Vref)(2ⁿ−1)]

Define the symbols from the worked case before substituting values. Keep units consistent, record the assumptions and round only after the calculation.

3. Follow a worked example

For an illustrative ideal 10-bit ADC with 5 V reference, 2.5 V maps to approximately 512. The endpoint scale is 5/1023 ≈ 4.89 mV per code. Real device transfer conventions should be checked in the datasheet.

4. Explore the model

Figure: calculated teaching cases; straight segments connect sampled points, not experimental observations. Read exact values below.

Illustrative scenario sweep — synthetic educational data
Input voltage (V)	Reference (V)	Ideal 10-bit code
0	5	0
2.5	5	512
5	5	1023

Sweep voltage from 0 to 5 V and clamp to the permitted input range. Observe the staircase quantisation.

5. Reproduce it yourself

Copy the input cases into Excel or a notebook and name each quantity and unit.
Recalculate each result from the stated equation or rule. For qualitative cases, explain the state or partition decision instead.
Change one input, predict the direction of change, then calculate again.
Write one sentence explaining where the model stops being valid.

6. Check your understanding

Approximately what code represents 1 V?

Reveal the answer and check your work

205 using this endpoint mapping.

Compare your result, units and reasoning. If they differ, return to the equation and test the worked case first.

7. Common mistake

Never apply a voltage above the board’s allowed input range.

Further study and academic note

Explore the discipline reference and further learning resources. This is an original IIMEEE introductory teaching note with synthetic examples; it is not a peer-reviewed research result or a professional design specification. Figures were constructed from the listed teaching cases. Resource links support further study and do not imply endorsement.