A limiter diode is often used in situations like this. 

Sometimes a simple hardware solution is best—it relies only on semiconductor 
physics and not correct software. 

Sent from my iPhone

> On Nov 9, 2020, at 9:40 PM, Lukas Haase via USRP-users 
> <[email protected]> wrote:
> 
> I need an output signal of ~32dBm (at 900 MHz).
> I have a MiniCircuits ZHL-25W-272+ high power amplifier (25W).
> The gain at 900 MHz is ~49.2.
> Hi,
> 
> 
> I would also like to filter out harmonics (USRP as well as PA) with a 
> VLF-1000+; the max input power is 10W (40dBm), so more than what I want to 
> obtain (32dBm).
> 
> My approach would be to connect the USRP output to the ZHL-25W-272+ and the 
> VLF-1000+ filter afterwards.
> 
> Hence, the USRP should output a maximum of 32dBm-49.2dB=-17.2dBm.
> 
> I can achieve this by setting the TX Gain to 0dB and adding a digital backoff 
> in my samples of ~5.9dB.
> 
> I think this should work but I am little bit concerned about safety if the 
> software fails for some reason or the wrong program is started accidentially. 
> The USRP can output up to 22dBm which would destroy the HPA and filter (and 
> what follows).
> 
> Is there a way to program a power limit in advance?
> What is the best/recommended way to handle this situation?
> 
> Thanks,
> Luke
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
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