Aspects of data acquisition system design

Analog-to-digital converters (ADCs) and digital-toanalog converters (DACs) play an important role in the design of data acquisition systems. ADCs are used to convert analog signals like the output from a temperature transducer, a radio receiver or a video camera into digital signals for processing. Conversely, DACs are used to convert digital signals back to analog signals. For example, the DAC accepts a digital video signal and outputs analog video to drive a monitor CRT, video amplifier or LCD monitor display. Convenience, cost, power dissipation, resolution, speed, supply voltage and ease of use drive the selection of a particular ADC/DAC. Ideally, designers will select an appropriate low-power serial or parallel input CMOS DAC, apply data and control signals to the device and have differential or single-ended analog outputs. Similarly, the requirements for low-power CMOS ADCs include being able to connect single-ended or differential input and control signals to the device and have accurate digital data at the output. It turns out that this is a non-trivial issue because of the wide range of input signals.