RF gain and damaging BladeRF input

Discussions related to schematic capture, PCB layout, signal integrity, and RF development

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RF gain and damaging BladeRF input

Post by fperal » Wed Mar 01, 2017 11:22 am

I have read that HackRF is recomended to be used with 0dB gain because RF amplifier has no filter and when trying to amplify some signal (let's say FM station) if we have some strong signal near (let say a mobile phone near the bladeRF) this strong signal may be amplified and destroy the RF input.
Can this happen to BladeRF too?


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Re: RF gain and damaging BladeRF input

Post by bglod » Wed Mar 01, 2017 3:06 pm

Absolutely! According to the LMS6 datasheet, the absolute maximum power the RF ports can be exposed to is +23 dBm (~200 mW). Beyond that, you will damage your front-end. For normal operation, you should keep the inputs well below that number. The ADC will saturate at around -13 dBm of input power.

This also applies to the transmit path. Never transmit into a poorly matched load (e.g. an open). Some percentage of output power will reflect back to the LMS and may cause damage.

If you're in an environment where you could be exposed to high-power signals, consider using an RF Limiter from MiniCircuits (or similar). You can also use appropriate filtering to allow just the bands you care about.
Electrical Engineer
Nuand, LLC.

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