An analog-to-digital converter that does frequency translation is described.
The need to characterize frequency sources, both in the laboratory and in the field, is increasingly important. The circuit in Figure 341.1 offers some interesting attributes in a compact and relatively inexpensive scheme. It uses an LTC1420 ADC to undersample a higher frequency, driving an LTC1668 DAC, followed by a filter to perform a down conversion. The output of the filter is subsequently resampled to produce a manageable sample rate for a single-chip microcontroller. In addition to characterizing ...