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As part of a circuit handling signals from a sound receiver, I'm apparently in need of a bridge rectifier that works at a frequency of 40 kHz. I came across this thread talking about how most are only reliable up to 10 kHz. Are there ones that exist that work at this high of a frequency or should I try to find another workaround?

Edit: I have linked the wrong thread

Transistor
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YaGoi Root
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4 Answers4

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I would just build your bridge rectifier out of discrete diodes; that gives you many more options:

Signal diodes tend to have better recovery characteristics than power diodes, in general. It's possible something as simple as 1N4148s will server your purposes.

Schottky diodes have no recovery time at all, due to being unipolar devices, but have significant reverse leakage and low blocking voltages. They also have a lower forward voltage than silicon pn diodes.

FREDs (fast recovery epitaxial diodes) have all the advantages of standard pn diodes with low reverse leakage and high blocking voltage, but they have recovery times in the tens of nanoseconds due to a light doping of either platinum or gold, which both act to shorten carrier lifetime.

Silicon carbide schottky diodes still have the zero recovery time that schottky diodes are known for, but due to the higher bandgap of SiC they can have extremely high blocking voltages and low reverse leakage--superior even to silicon pn diodes. They're pricier than silicon diodes, but still affordable until you start needing truly absurd specs. Note that the forward voltage of a SiC schottky is typically higher than a silicon pn diode, so you do lose out a bit in that regard. You can mitigate this somewhat by using diodes rated for much higher current than what you intend to use them at.

PIN diodes are also used for RF purposes, but I'm not as familiar with those as the other types on this list. They do have lower carrier lifetimes, so they may meet your requirements.

I have no idea about the recovery characteristics of vacuum tube diodes, but I would think they're probably pretty good, since they're also unipolar devices... but I strongly doubt their advantages would even come close to outweighing the downsides (need to power the heaters, which wastes energy; need to replace them periodically; expensive; hard to get....).

Hearth
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A rf mixer is similar in structure to a full-bridge rectifier, and they work in the GHz range easily.

picture from here

Yet Another Michael
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Part of the problem is there's little market for bridge rectifiers at that frequency, once you go past a few kiloherts it's cheaper to do a push-pull rectifier or even half-wave than to do a full bridge.

so if you need a full bridge you'll be making it from the available individual or paired diodes. eg: 2x BAT54S can make a bridge.

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Bridge rectifiers are made of diodes and diodes at high frequencies they don't operate well due to relatively big recovery times.You should search for a bridge rectifier made of shottky diodes which have more frequency tolerance than normal diodes.

Miss Mulan
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  • For most diodes that you run across maybe particularly power diodes. But other diodes exist specifically for signals and not always made out of silicon. Germanium diodes, for instance are used to rectify RF. They work just fine. It's a bit mind boggling when you think about it. – DKNguyen Mar 16 '21 at 23:54
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    Check out the schematic of a crystal radio: https://en.wikipedia.org/wiki/Crystal_radio – DKNguyen Mar 17 '21 at 00:05
  • The ubiquitous 1N4148 has a reverse recovery time of 4 ns and is as good as it gets for standard silicon and 40 kHz would be a breeze for it. So, when you say "diodes at high frequencies they don't operate well due to relatively big recovery times" you are over-generalizing and painting a bad picture of silicon that just isn't true. Note that although your answer is "not good", I'm explaining what is wrong with it rather than downvoting. That's the sensible way on this site. I see someone else has downvoted it and that is usually a warning that something you have said is wrong. – Andy aka Mar 19 '21 at 17:19