Typical applications involving transformer-coupled circuits are discussed in this section. To ensure good amplitude and phase balance at the analog inputs, transformers (such as TC1-1-13 and TC1-1-43) can be used from the dc to 1000-MHz range and from the 1000-MHz to 4-GHz range of input frequencies, respectively. When designing the driving circuits, the ADC input impedance (or SDD11) must be considered.

By using the simple drive circuit of Figure 9-10, uniform performance can be obtained over a wide frequency range. The buffers present at the analog inputs of the device help isolate the external drive source from the switching currents of the sampling circuit.

Figure 9-10 Input Drive Circuit