In this chapter, fundamental aspects of analog-to-digital (A/D) and digital-to-analog (D/A) converters are presented without regard for their internal architecture or circuit design. In effect, converters are treated in this chapter as black boxes such that only their input–output relationships are discussed. Internal architectures and circuits techniques for realizing data converters are discussed in following chapters.
Before proceeding, it is useful to make the distinction between two main types of data converters.
Nyquist-Rate Converters We loosely define Nyquist-rate data converters as those converters that generate a series of output values in which each value has a one-to-one correspondence with a single input value. For example, a Nyquist-rate D/A converter would generate a series of analog output levels, where each level is a result of a single B-bit input word. However, it should be noted that Nyquist-rate converters are seldom used at the Nyquist rate due to the difficulty in realizing practical anti-aliasing and reconstruction filters. In most cases, Nyquist rate converters operate at 1.5 to 10 times the Nyquist rate (i.e., 3 to 20 times the input signal’s bandwidth).
Key Point: In Nyquist-rate converters, there is a one-to-one correspondence between input and output values. Oversampling converters increase SNR by operating much faster than the input signal’s Nyquist ...