An analogue electronic system processes signals that vary continuously, while a digital electronic system processes signals represented by discrete values, usually binary states such as 0 and 1.
How the systems work
In an analogue system, a physical quantity such as temperature, light intensity or sound is converted by an input transducer into a continuously varying electrical signal. For example, a temperature sensor might produce any voltage within a range, so small temperature changes produce corresponding voltage changes.
A digital system represents information using separate numerical levels. In binary electronics, a low voltage is interpreted as logic 0 and a high voltage as logic 1. If the original sensor signal is analogue, an analogue-to-digital converter (ADC) samples and quantizes it before a processor can use it.
| Feature | Analogue system | Digital system |
|---|---|---|
| Signal | Continuous range of values | Discrete values, usually binary |
| Processing | Uses components such as amplifiers and filters | Uses logic gates, microcontrollers or processors |
| Noise | Noise directly alters the signal and can accumulate | Signals can often be regenerated as clear logic states |
| Precision | Limited by component tolerances and noise | Limited by sampling rate and bit resolution |
| Example | Analogue audio amplifier | Digital thermometer with a numerical display |
Digital does not automatically mean perfectly accurate. During sampling, measurements are taken at intervals, and quantization assigns each measurement to one of a limited number of levels. Information may therefore be lost when an analogue signal is converted into digital form.
A common misconception is that analogue means “old” and digital means “modern.” The distinction concerns how information is represented and processed, not the age of the product.
Exam technique
For IB Design Technology HL subtopic A3.4, define both signal types and compare them directly. In an application question, trace the system through input, process and output, identifying any ADC or digital-to-analogue converter and explaining why it is required.
