AMIS-52150 Datasheet, PDF (14/21 Pages) AMI SEMICONDUCTOR – Low-Power Transceiver with Clock and Data Recovery

AMIS−52150
Figure 11. DAC Slice Mode Waveform
In the Average mode, the threshold value is generated
automatically. This threshold value is then compared to the
output of the slice circuit to re-create the digital data. The
slice circuit along with an external capacitor are used to
generate a charging time constant which is equal to charging
to 95 percent of a bit level in two bit time periods. The data
protocol should add a header to the data to allow the slice
circuit to determine the average level. Figure 12 shows a
typical waveform for the Average mode. Table 21 shows the
control registers for the auto slice modes.
Figure 12. Average Slice Mode Waveform
In the Peak mode, a threshold value is generated
automatically as well. This threshold value is then compared
to the output of the slice circuit to re-create the digital data.
The operation of the slice circuit is based on an external
capacitor with an internal peak detector, in order to arrive at
the peak value of the data waveform. The threshold value is
set 6 dB below this peak value. The capacitor value should
be selected so that the peak detector does not discharge
during periods of continuous zeros, while being small
enough to allow the peak detector to reach the peak value
quickly. Figure 13 shows a typical waveform for the Peak
mode.
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