How do I choose between the J2100A, J2101A and J2110A?

If you plan to measure PFC’s, then the J2100A is a good choice, whereas the J2110A is a better choice if you need to measure linear regulators, dc/dc converters, POL regulators or other typical analog control loops above 10Hz.

If you need bandwidth below 1Hz or above 10MHz the J2110A is the best choice, though it is limited to +/-10Vpk.   Also, the J2110A is an electronic injector and therefore the load current is not transferred to the injector input as in a transformer.  For this reason it is important to select an injection location that presents a low impedance to the input and a high impedance to the output of the J2110A.  For most linear regulators (below 10V) this means that the linear regulator output connects to the J2110A input and the regulator voltage divider connects to the J2110A output.