I have designed a AC-coupled non-inverting amplifier circuit as shown in the picture below. Thanks to the help of this forum the amplfier itself is stable and so far the results are quite promising. However when i do a spectrum analysis at the output without any input signal there is an unexpected spur at 250kHz. I have already inspected the power supply but no matter which power supply i use, the spur is still present. Is there anything in my circuit which would create such an issue? Any help would be appreciated.