Analog-to-digital converters (ADCs) translate analog signals -- real-world signals like temperature, pressure, voltage, current, distance, or light intensity -- into a digital representation of that signal. This digital representation can then be processed, computed, transmitted, or stored.
In many cases, the a-d conversion is just one step within a larger measurement and control loop where digitized data is processed and then reconverted back to analog signals to drive external transducers. These transducers include motors, temperature controls, and speakers. The performance required of the ADC will reflect the performance goals of the measurement and control loop. ADC performance needs will also reflect the capabilities and requirements of the other signal-processing ele-ments in the loop.
An ADC samples an analog waveform at uniform time intervals and assigns a digital value to each sample. The digital value appears on the converter’s output as a binary or binary coded decimal (BCD). The value is obtained by dividing the sampled analog input voltage by the reference voltage and then multiplying by the number of digital codes. The number of codes is, in turn, a function of the converter’s resolution or the number of bits available on the ADC output.