Digital‑Analog Conversion: Fundamentals, ADCs, and DACs

Integrating digital circuitry with sensor devices is straightforward when the sensors themselves are digital—switches, relays, and encoders naturally interface with gate logic because their signals are binary on/off.

When analog devices enter the picture, the interface becomes considerably more involved. To bridge the gap, electronic components must translate continuous analog signals into discrete digital values and vice versa. An analog‑to‑digital converter (ADC) performs the former conversion, while a digital‑to‑analog converter (DAC) handles the reverse.

In an ADC, an analog electrical signal—typically a voltage or current—is sampled and quantised into a binary number that can be processed by digital systems. The block‑diagram representation of an ADC is shown below:

Conversely, a DAC accepts a binary input and synthesises a corresponding analog voltage or current. The block diagram for a DAC is illustrated here:

Together, ADCs and DACs provide a complete interface for digital systems that must interact with analog sensors and actuators. A common application is in automotive engine control units, where sensor readings are converted to digital data for processing, and control commands are converted back to analog signals to drive actuators.

In practice, converting a digital signal to an analog one is typically simpler than performing the reverse operation. Accordingly, we begin by examining DAC circuitry before exploring ADC design.

RELATED WORKSHEET:

• Digital‑to‑Analog Conversion Worksheet