I need to account for both the "on" and "off" impedance of the ADG904 (absorptive) in the signal path for switching among four 50 ohm VHF sources. Measurements across the frequencies of interest with the part connected solely and directly to a 50 ohm resistive load show that the the part has a nontrivial reactive component in the "on" state.
These measurements don't seem to fit a simple lumped parameter model of the part. Is there an existing SPICE model that I can use for this purpose that has been verified experimentally against the real part? Is there impedance characterization data that is available?