Analog Devices Edition: Current feedback amplifier models not working

[CoreyA]

Hi, I'm using the Analog Devices version of Multisim and have problems simulating their current feedback amplifers. For example, I want to use the AD8000 as an inverting transimpedance amplifier, basically run a current into the inverting input, ground the non-inverting input, and chose the feedback resistor to be the transimpedance. I want to make sure that I can use feedback resistors between 100 and 2000 Ohms to convert negative current pulses to positive voltage pulses, but I can't get anything to work, even with the recommended feedback resistor values. With a current input I get negative rail saturation, while with a voltage input I get a step output.

Thank you.

[yyao]

Hi there,

I think I figured out why your circuit isn't working. It has to do with the treatment of the dedicated feedback output pin that exists on your amplifier. While this pin and the main output pin both exist on the physical package and are electrically connected, this isn't the case in Multisim. The feedback pin in Multisim exists on the schematic only, it doesn't actually have any simulation functionality. So, as a workaround, I suggest that you connect the feedback path to the output pin instead of the dedicated feedback pin. You would never do this in real life, but for simulation, it will work fine.

Thanks for pointing this out. We will look into this problem and have it fixed in the future.