Digital Signal Processing Reference
In-Depth Information
Figure 2.8
Using DASP technology leads to significant widening of the operational frequency
range for the existing ADC
needed sampling rate does not directly depend on the upper frequency of the
signal. Only the other mentioned ADC parameter, namely the bandwidth of the
input, restricts this upper frequency. However, as in most cases this bandwidth is
much wider for a given ADC than half of the permitted sampling rate, using the
DASP technology typically increases the frequency limit to a level that is several
times higher.
Figure 2.8 illustrates this effect. This diagram, plotted on the basis of typical
ADC data taken from manufacturers' catalogues, shows how much the application
range of the existing ADC could be widened in the frequency domain by paying
attention to the signal digitization processes and by changing the signal process-
ing techniques. It can be seen that using the DASP approach extends the upper
frequency limits of the application ranges of the considered ADC to frequencies
that are several times higher.
Note that two kinds of benefits could be obtained as a result of this effect. In
the lower frequency range, covered by many types of ADC, application of DASP
typically leads to cost savings as relatively low-priced converters can often be used
in this frequency range instead of more expensive devices. On the other hand,
only a few types of ADC could be used in the customary way in the indicated
region of the higher frequencies. In this frequency range, application of DASP
results in significant enlargement of the frequency range where signals can be
processed fully digitally. However, the most important benefit is the possibility
