Resolution and quantization

Turn a voltage into a number

ADC means Analog to Digital Converter: it maps an input voltage to a number. Resolution in bits sets how many codes exist: 2^bits. Quantization groups a continuous range into steps. The reference voltage sets the top of that range. A bit is one binary digit, either 0 or 1.

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EXPERIMENT BENCH

Change the circuit settings, predict the readings, then check a challenge. These are learning models, with the assumptions explained in each lesson.

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Why it works

Ideal ADC rounds downward and clips to its code limits. No noise, input loading, sampling delay or calibration error. The sensor slider represents 0–5 V.

Step = Vref/2^bits. Code = floor(Vin/step), limited to 0…2^bits − 1. floor means round down. A smaller step distinguishes smaller voltage changes. Vin is input voltage; Vref is reference voltage.

Difficulty

Build · Build it
Power on at 8 bits, a 5 V reference and 50% sensor level. Read code 128.
Need a hint?
8; 5 V; 50% → 128
Explore · Change one thing
Select 10 bits, a 5 V reference and 25% sensor level. Read code 256.
Need a hint?
10; 5 V; 25% → 256
Solve it · Solve the challenge
Select 12 bits, a 2.5 V reference and 80% sensor level. Observe saturation at code 4095.
Need a hint?
12; 2.5 V; 80% → 4095

Extra reading and circuit recipes