Re: [Discuss-gnuradio] Gauging interest for an SDR PA

The latest GaN devices seem impressive, many rated at DC to 4GHz.
But the reality is whether impedance matching circuit can reach 50MHz to 3GHz bandwidth.

The problem is power efficiency and thermal dissipation.

Especially when you combine boost DC supply, you're not going to have a heat sink fitting into a cigarette pack size.

Best power efficient of RF device is at saturated power, but often SDR signals have high peak-to-average power ratio, and must be backed off so only the power peaks reach saturation.

Seems alot of these challenges are addressed with whats known as "class E" or drain modulation / polar modulation.

On Tue, Nov 26, 2013 at 6:37 PM, Louis Brown <rfengr@everestkc.net> wrote:

Given the availability of SDR hardware (USRPs, BladeRF, HackRF, etc) covering VHF through S/C bands, is there any interest in a wide band power amp to complement this hardware?  GaN seems to be ubiquitous now, and there are medium power, 48 VDC parts available in low cost SMT packages.  So I think it's feasible for something like:

50 MHz - 3 GHz bandwidth
Class AB
5 - 30 VDC supply (high efficiency, high frequency boost supply)
10 dBm drive
37 dBm Psat
Robust to full mismatch (open/short)
Logic level enable
ALC with VSWR monitoring (serial, I2C, etc)
Small (cigarette pack or smaller)
Low cost
Open source



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