I am student from Slovakia and I have problem about differantial amplifier ada4927 (I need bandwidth 25 MHZ and almost same input resistors). I would like to control gain with 1 pair of JFETs in linear region, which are connected to inverting and non-inverting inputs (like this http://electronicdesign.com/site-files/electronicdesign.com/files/archive/electronicdesign.com/files/29/10116/figure_01.gif ), but I need to use just single output instead of differential output - I solved this with removed feedback resistor to FD+ and grounded OUT- with resitor => I need to use just OUT+. It is possible and correct to do that? Positive feedback caused non-linearity probably because input resistors weren´t same.
Best Regards, Tomas