Hi guys,
I have a 3-stage optical detector and amplifier using LMH6702 as depicted below.
I am using it for 20-50 MHz pulse detection.
The circuit with only the first two stages works great and I don't have any problem with that. But when the third stage is added, Vout for a grounded input is oscillating in a weird shape (at ~1.67 KHz) as follows:
Does any one have any idea what could be the reason for such a oscillation?
The circuit is implemented on PCB and I have considered all the design rules from the datasheet and application notes.
I greatly appreciate any help.
Thanks,
Moha