4 Replies Latest reply on Jul 26, 2015 11:12 PM by BoonT_56

    Large transients at Start andStop of RF transmission


      I'm have a very noise sensitive high gain amplifier for which I'm communicating with via BCM20732s. As I've been designing and debugging trying to keep the RF out of my amplifier, I've found that the biggest problem are transients when the RF transmission power is switched on and switched off. Oddly during the time the RF is on, I don't see disruption. The question I have is what is causing this and how can it be minimized? I believe it must be a very sharp voltage dip/rise on the supply when the RF kicks on/off causing radiation. It is very consistent, always inducing a negative detected impulse when the RF starts up and positive impulse when it turns off. Perhaps someone who works on the PA can comment.  Is there any way to limit the slew-rate of the RF power on transition? I had originally looked for a software solution (i.e. using a gating signal from the chip when the RF is on) unfortunately there is not such signal that can be routed out on the 20732 to indicate the RF is on.  Any help with understanding these transients and minimizing them would be greatly appreciated.