Question
I´m using the spice model of the ADG884. In the datasheet the -3dB Bandwidth is
18MHz. In the simulation the result is about 1.7GHz. Is the analog bandwidth of
the signal chain not contained in the Spice model?
Answer
The SPICE Model of ADG884 contains correct bandwidth value. The simulation of
bandwidth is not possible with a AC sweep simulation. Please have a look at
attachment.
For bandwidth simulation a network analyzer is needed. I simulated in MultiSim
12.0 with Network analyzer XNA1 of Agilent. It matches input and output with a
50 Ohm resistor.
The simulation result is very precise. The S-Parameter s21 shows Vout/Vin. At
-3dB amplitude decrease (upper chart, page 2), or at -45° phaseshift (lower
chart, page 2)you have a frequency of about 18 MHz.
The attached measurement shows at -45.134° phase shift a frequency/bandwidth of
17.78MHz.