ADCs and Sampling

Almost all real signals are analog by nature and almost all measurement systems are digital. That means that in most measurement systems, the signal must be converted from the analog world to the digital world and a basic understanding of this process is paramount. First, quantization and quantization noise are discussed in general and then a few different analog-to-digital converter techniques (ADCs) are presented. The first one is the successive approximation ADC (SAR) followed by the flash ADC, the pipeline ADC, and the dual slope ADC. Level-crossing ADCs and the sigma-delta ADCs are also presented (but they are less common in the physics lab). The theory also includes the concept of an equivalent number of bits (ENOB) and ‘dithering’. This chapter also digs a little deeper into the sampling process; the benefit of oversampling and how to achieve extreme sampling rates (time-interleaved sampling and equivalent-time sampling).