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Re: Gate resistor for lateral power MOSFET?

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Frank Miles wrote...
> Winfield Hill wrote:
>> Frank Miles wrote...
>>> Winfield Hill wrote:
>>>> 
>>>> I wasn't in the discussion, but would like to point out / remind
>>>> anyone interested, of my 200 W amplifier project of last fall. 
>>>> This has a 1000 V/us slew rate and a DC to 10 MHz response
>>>> (-3dB rolloff frequency).
>>>> But ahem, it doesn't use lateral MOSFETs.
>>>
>>> I'm sorry, Win - I didn't recall that.  I have no vested interest in
>>> the lateral MOSFETS.  Is there a web link or at least a title that I
>>> might search for?
>> 
>>  I don't remember the s.e.d. subject, and just now I couldn't find the
>>  folder I made on DropBox, for you s.e.d. blokes and a DIY-audio
>>  discussion, so I created a new one, see AMP-70A under s.e.d.
>> https://www.dropbox.com/sh/mkoqdo5y0b9fevm/AACBM7iDdTyRLFADqLgj7ljNa?
>dl=0
>
>That was so nice for you to post this, thanks!  I remember seeing it
>now, though I'd forgotten it before I began the project with the power
>amp requirement.
>
>One prominent note in your schematic warns about using the 1-ohm output
>apparently due to lack of protection.  You may not have needed the low-
>resistance output (though that seems strange given the 5A - losing over
>1kW is a lot of heat!) - but did you find that active shutdown schemes
>were too slow to protect your amplifier?  (I haven't yet done this with
>my amplifier)

 Another CAD schematic version includes a fast shutoff scheme,
 but I didn't implement that on this prototype.  The amplifier
 is (almost) fast enough to be a 50-ohm RF source, but the real
 usefulness comes from its high-current output, despite what
 the drawing says.  We've been using two of them that way for
 almost a year, and nothing failed.  Actually, we fried the
 electrode system, but the amplifier survived.  Knock on wood. 

 Using BJTs at high currents and high Vce invites disaster; the
 180V 2SC4883A 2SA1859A have a much smaller SOA than I'd like. 
 That's because they're small die parts with fT = 60 and 120MHz.
 We've been lucky so far.  I also designed a fast SOA-sensing
 protection circuit, but haven't implemented that either.  As
 it stands, the AMP-70A design is just a high-speed test bed.
 I have modifications extending its slew rate to 2 or 3kV/us.
 Keep up this kind of business long enough and eventually
 something will blow out!


-- 
 Thanks,
    - Win

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Thread

Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-09-28 17:46 +0000
  Re: Gate resistor for lateral power MOSFET? John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-28 11:35 -0700
    Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-09-28 22:22 +0000
      Re: Gate resistor for lateral power MOSFET? John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-28 17:20 -0700
  Re: Gate resistor for lateral power MOSFET? Winfield Hill <hill@rowland.harvard.edu> - 2016-09-28 19:16 -0700
    Re: Gate resistor for lateral power MOSFET? Phil Allison <pallison49@gmail.com> - 2016-09-28 23:07 -0700
      Re: Gate resistor for lateral power MOSFET? Winfield Hill <hill@rowland.harvard.edu> - 2016-09-29 12:51 -0700
  Re: Gate resistor for lateral power MOSFET? Phil Allison <pallison49@gmail.com> - 2016-09-28 19:52 -0700
    Re: Gate resistor for lateral power MOSFET? Winfield Hill <hill@rowland.harvard.edu> - 2016-09-28 20:13 -0700
      Re: Gate resistor for lateral power MOSFET? Winfield Hill <hill@rowland.harvard.edu> - 2016-09-29 12:52 -0700
    Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-09-29 16:41 +0000
      Re: Gate resistor for lateral power MOSFET? Phil Allison <pallison49@gmail.com> - 2016-09-29 18:52 -0700
        Re: Gate resistor for lateral power MOSFET? boB <boB@theresnoplacelikehome.com> - 2016-09-30 00:54 -0700
          Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-09-30 15:57 +0000
        Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-09-30 15:53 +0000
          Re: Gate resistor for lateral power MOSFET? George Herold <gherold@teachspin.com> - 2016-09-30 09:19 -0700
          Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-09-30 20:04 +0000
            Re: Gate resistor for lateral power MOSFET? Winfield Hill <hill@rowland.harvard.edu> - 2016-09-30 14:07 -0700
              Re: Gate resistor for lateral power MOSFET? dplatt@coop.radagast.org (Dave Platt) - 2016-09-30 14:52 -0700
              Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-10-01 17:29 +0000
                Re: Gate resistor for lateral power MOSFET? Winfield Hill <hill@rowland.harvard.edu> - 2016-10-01 12:19 -0700
                Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-10-02 02:59 +0000
                Re: Gate resistor for lateral power MOSFET? Phil Allison <pallison49@gmail.com> - 2016-10-01 21:10 -0700
                Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-10-03 00:20 +0000
                Re: Gate resistor for lateral power MOSFET? Winfield Hill <hill@rowland.harvard.edu> - 2016-10-02 09:43 -0700
                Re: Gate resistor for lateral power MOSFET? Frank Miles <fpm@u.washington.edu> - 2016-10-03 00:33 +0000
          Re: Gate resistor for lateral power MOSFET? Phil Allison <pallison49@gmail.com> - 2016-09-30 22:40 -0700

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