7.3.3 Digital Output

A differential input signal of 0 V ideally produces a stream of ones and zeros that are high 50% of the time and low 50% of the time. A differential input of 250 mV produces a stream of ones and zeros that are high 89.06% of the time. A differential input of –250 mV produces a stream of ones and zeros that are high 10.94% of the time. This is also the specified linear input range of the modulator with the performance as specified in this data sheet. The range between 250 mV and 320 mV (absolute values) is the non-linear range of the modulator. The output of the modulator clips with a stream of only zeros with an input less than or equal to –320 mV or with a stream of only ones with an input greater than or equal to 320 mV. The input voltage versus the output modulator signal is shown in Figure 47.

The system clock of the AMC1204 and AMC1204B is typically 20 MHz and is provided externally at the CLKIN pin. The data are synchronously provided at 20 MHz at the DATA output pin. The data are changing at the falling edge of CLKIN; for more details see the Timing Requirements section.

Figure 47. Analog Input Versus Amc1204 Modulator Output