I need 5V, 12V, and 30V power supplies for an RF front end tuner. I'd like to power them with a single AC adapter, either 12 or 18V. Obviously it needs to be pretty clean to function with RF. The tuner + power supply will be on a single PCB with a ground plane. I'm mostly concerned about getting the 30V supply. How should I go about this, and what design considerations should I pay attention to?
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\$\begingroup\$ and the current requirement at each voltage is? \$\endgroup\$– JIm DeardenCommented Apr 15, 2015 at 18:07
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\$\begingroup\$ Unfortunately I don't have that... I'm assuing less that .5A on each. Here's the datasheet if you can glean some information: mtmscientific.com/tuner.pdf \$\endgroup\$– crocboyCommented Apr 15, 2015 at 18:09
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\$\begingroup\$ Maximum current draw is on the +12V bus, which is 200mA. \$\endgroup\$– crocboyCommented Apr 15, 2015 at 18:52
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1 Answer
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To get to 0.5 A at 30 V you will essentially need a boost converter. If the current requirement can be dropped substantially (maybe 100 mA, maybe 10 mA, I'm not familiar with what's available at these voltages), you could consider a switched capacitor voltage converter.
If you need low noise, you will then most likely have to filter the output to achieve your noise requirement.
The filtering problem will be easier if you choose a switching frequency far away from your rf operating frequency (and without harmonics interfering with your rf operating frequency).
answered Apr 15, 2015 at 18:34
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\$\begingroup\$ RF is ~400MHz, most boost converters I've seen have ~1MHz switching frequency, so hopefully it's not a problem \$\endgroup\$– crocboyCommented Apr 15, 2015 at 18:35
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\$\begingroup\$ Yes, that's a good separation. If your rf was 1 or 10 MHz, though, you'd have a trickier problem. \$\endgroup\$ Commented Apr 15, 2015 at 18:55
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\$\begingroup\$ Also, my max current draw is on the 12V, which is 200mA. I wonder if I could get away with using a 12V adapter and using a simple 30V step up? \$\endgroup\$– crocboyCommented Apr 15, 2015 at 18:56
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\$\begingroup\$ @crocboy, You really need to figure out your 30 V current load before you can go further. \$\endgroup\$ Commented Apr 15, 2015 at 18:57
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