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ADISim PLL tool Active filters

Question asked by kafkas on Dec 23, 2011
Latest reply on Jan 5, 2012 by rbrennan



I am currently using ADF4157 as frequency synthesizer in my PLL design together with active filter in which I use AD797A as opamp. I am using this opamp in single supply configuration. You can see my system in the attached drawing.


In ADISim tool active filter is shown but bias details are not shown. So I used single supply ( Vs :10V and Vs-:GND ). Also I left Vin+ opened but in this configuration filter does not work. Output is always pulled to Vs levels which is around 9.1V. By the way I am sure that my Synthesizer is working correctly.


Can you suggest a solution to this problem?