Nyquist-Rate ADC and DAC
The rapidly growing electronics field has witnessed the digital revolution that started with the digital telephone switching system in the early 1970s. The trend continued with digital audio in the 1980s and with digital video in the 1990s. The digital technique is expected to prevail in the coming multimedia era and to influence even future wireless PCS/PCN systems. All electrical signals in the real world are analog in nature, and their waveforms are continuous in time. Since most signal processing is done numerically in discrete time, devices that convert an analog waveform into a stream of discrete digital numbers, or vice versa, have become technical necessities in implementing high-performance digital processing systems. The former is called an analog-to-digital converter (ADC or A/D converter), and the latter is called a digital-to-analog converter (DAC or D/A converter).