I have just realised that the output bandwidth is 30MHz and my modulation frequency is 3MHz. So I have put in an external capacitor 100pF on PFLT (C8) to lower the output bandwidth to 0.3MHz. This has helped and I don't get any wild fluctuations. However, my question still remains, can the AD8302 be considered as a lock-in amplifier? If not, what are the reasons?
thanks
Andy