An empedance matcher transforms the maginitude and phase of the voltage and current of a signal such that a desired impedance is presented to a cascaded network. Passive impedance transformers have no power gain of course. For the unity gain buffer amplifier the voltage is not changed but the...
As the pdf explains, the loading impedance of the cascaded filter changes the effective transfer function of the first filter stage compared to when it is calculated (or measured) without the cascaded filter (and the cascaded filter transfer function is also changed by the impedance of the...