Figure 2a shows a single cycle of a sine wave for the input of a DS modulator. This single cycle has voltage ampli tude that changes with time. Figure 2b shows a frequency-domain representation of the time-domain signal in Figure 2a. The curve in Figure 2b represents the continuous sine wave in Figure 2a and appears as a straight line or a spur. There are two ways to look at the DS modulator—in the time domain (Figure 3) or in the frequency domain (Figure 4). The time-domain block diagram in Figure 3 shows the mechanics of a first-order DS modulator. The modulator converts the analog input signal to a high-speed, single-bit, modulated pulse wave. More importantly, the frequency analysis in Figure 4 shows how the modulator affects the noise in the system and facilitates the production of a higher-resolution result. The DS modulator shown in Figure 3 acquires many samples of the input signal to produce a stream of 1-bit codes. The system clock implements the sampling speed, fS, in conjunction with the modulator’s 1-bit comparator.