Hi Marcus, This is a great idea. Unfortunately PIN diodes rarely exist as "coax" modules (but rather MMICs to be integrated on a board).
The few coax modules I found from Mini-Circuits and RF-Lambda are for high powers (>0dBm). For me, the max. output would need to be ~ -16dBm. Best regards, Lukas > Gesendet: Montag, 09. November 2020 um 22:53 Uhr > Von: "Marcus D Leech" <[email protected]> > An: "Lukas Haase" <[email protected]> > Cc: [email protected] > Betreff: Re: [USRP-users] Limiting output power, best approach to connect HPA? > > 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 > > > > > > > > > > _______________________________________________ USRP-users mailing list [email protected] http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
