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Paralleling ADL5565, is possible?

Question asked by mvv on Nov 14, 2014
Latest reply on Nov 19, 2014 by mvv

I design instrumentation functional generator that should work from DC to at least 480 MHz, and have 3-4 dBm output power at single-ended 50 Ohm load with IMD3 better than -60 dBc. I select ADL5565 and will use it with +/-2,5 volts power supplies. Because i need pure DC, i can't combine differential power to single-ended using a balun. And because ADL5565 optimized to 100 Ohm single-ended output, i should add additional 50 Ohm in series to output wire and additional get -6 db loss. I see Circuit Note CN0268, which contains some details show that it suitable directly for 50 Ohm single-ended load (100 Ohm diff) as shown on fig. 3, but not shown how much dBm is these graphs.

So i think about paralleling two ADL5565s due to i think i can get benefit of that they loaded by like 100 Ohm (single-ended) each (and power will sums).

But our local experienced engineer says that paralleling will give unpredictable results.

So i ask for help Analog Devices Team, is paralleling two ADL5565s correct or not?

Thanks so much.