Forums

diode recovered charge

Started by John Larkin September 6, 2014
On Sun, 14 Sep 2014 13:08:02 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Sun, 14 Sep 2014 12:53:09 -0700, John Larkin ><jlarkin@highlandtechnology.com> wrote: > >>On Sun, 14 Sep 2014 12:44:19 -0700, Jim Thompson >><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >>>On Sat, 06 Sep 2014 12:31:46 -0700, John Larkin >>><jlarkin@highlandtechnology.com> wrote: >>> >>>> >>>>I got curious about the amount of reverse-recovery charge in PN >>>>diodes, as a function of forward current (and time of fwd bias) and >>>>diode size/type. >>>> >>>>Question is, are the LT Spice diode models realistic? We'll have to >>>>test some diodes to see. Since diode recovery for a given part number >>>>depends a lot on the manufacturer, we should stick to sole-source >>>>parts and tweak the Spice model to align with reality. >>>> >>>>The ES1D below, straight from the LT Spice diode list, seems to have a >>>>definite step-recovery behavior, which probably isn't realistic. It >>>>stores 115 nC when biased to 1 amp forward. The recovered charge is >>>>not a function of ON time, also unrealistic. >>>> >>>> >>>[snip] >>> >>>None of the ordinary Spice variants seem to model forward and reverse >>>recovery time. >>> >>>Can you provide some scope photos of forward and reverse recovery at >>>different current levels? >>> >>>Several papers I've run across suggest that a fairly simple subcircuit >>>may be possible... but, being IEEE crap, their data is naive and vague >>>>:-} >>> >>> ...Jim Thompson >> >>I posted some 1N914 pics, taken at four different current step levels. > >I saw those but couldn't determine the current levels... that green >drives my eyes nuts.
The P400 DDG box display (not all that easy to read either) shows the VH and VL open-circuit voltages from the 50-ohm generator. The diode is across the transmission line from the pulse gen to the 50 ohm scope. There's a 20 dB attenuator on the sampling head input. So the diode sees a 25 ohm source, at half the voltage on the DDG display.
> >> >>Looks sorta like constant-area overshoot. >> >>Forward recovery doesn't matter in my current application, since I'll >>have plenty of time to pump current into my diodes. Controlling the >>amount of reverse charge matters, and I need to simulate reverse >>recovery accurately in the higher-level simulation. > > > ...Jim Thompson
-- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Sun, 14 Sep 2014 13:17:03 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

>On Sun, 14 Sep 2014 13:08:02 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: > >>On Sun, 14 Sep 2014 12:53:09 -0700, John Larkin >><jlarkin@highlandtechnology.com> wrote: >> >>>On Sun, 14 Sep 2014 12:44:19 -0700, Jim Thompson >>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>> >>>>On Sat, 06 Sep 2014 12:31:46 -0700, John Larkin >>>><jlarkin@highlandtechnology.com> wrote: >>>> >>>>> >>>>>I got curious about the amount of reverse-recovery charge in PN >>>>>diodes, as a function of forward current (and time of fwd bias) and >>>>>diode size/type. >>>>> >>>>>Question is, are the LT Spice diode models realistic? We'll have to >>>>>test some diodes to see. Since diode recovery for a given part number >>>>>depends a lot on the manufacturer, we should stick to sole-source >>>>>parts and tweak the Spice model to align with reality. >>>>> >>>>>The ES1D below, straight from the LT Spice diode list, seems to have a >>>>>definite step-recovery behavior, which probably isn't realistic. It >>>>>stores 115 nC when biased to 1 amp forward. The recovered charge is >>>>>not a function of ON time, also unrealistic. >>>>> >>>>> >>>>[snip] >>>> >>>>None of the ordinary Spice variants seem to model forward and reverse >>>>recovery time. >>>> >>>>Can you provide some scope photos of forward and reverse recovery at >>>>different current levels? >>>> >>>>Several papers I've run across suggest that a fairly simple subcircuit >>>>may be possible... but, being IEEE crap, their data is naive and vague >>>>>:-} >>>> >>>> ...Jim Thompson >>> >>>I posted some 1N914 pics, taken at four different current step levels. >> >>I saw those but couldn't determine the current levels... that green >>drives my eyes nuts. > >The P400 DDG box display (not all that easy to read either) shows the >VH and VL open-circuit voltages from the 50-ohm generator. The diode >is across the transmission line from the pulse gen to the 50 ohm >scope. There's a 20 dB attenuator on the sampling head input. > >So the diode sees a 25 ohm source, at half the voltage on the DDG >display. > > > > >> >>> >>>Looks sorta like constant-area overshoot. >>> >>>Forward recovery doesn't matter in my current application, since I'll >>>have plenty of time to pump current into my diodes. Controlling the >>>amount of reverse charge matters, and I need to simulate reverse >>>recovery accurately in the higher-level simulation. >>
OK. That gives me enough info to "play". ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Sun, 14 Sep 2014 13:19:21 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Sun, 14 Sep 2014 13:17:03 -0700, John Larkin ><jlarkin@highlandtechnology.com> wrote: > >>On Sun, 14 Sep 2014 13:08:02 -0700, Jim Thompson >><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >>>On Sun, 14 Sep 2014 12:53:09 -0700, John Larkin >>><jlarkin@highlandtechnology.com> wrote: >>> >>>>On Sun, 14 Sep 2014 12:44:19 -0700, Jim Thompson >>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>> >>>>>On Sat, 06 Sep 2014 12:31:46 -0700, John Larkin >>>>><jlarkin@highlandtechnology.com> wrote: >>>>> >>>>>> >>>>>>I got curious about the amount of reverse-recovery charge in PN >>>>>>diodes, as a function of forward current (and time of fwd bias) and >>>>>>diode size/type. >>>>>> >>>>>>Question is, are the LT Spice diode models realistic? We'll have to >>>>>>test some diodes to see. Since diode recovery for a given part number >>>>>>depends a lot on the manufacturer, we should stick to sole-source >>>>>>parts and tweak the Spice model to align with reality. >>>>>> >>>>>>The ES1D below, straight from the LT Spice diode list, seems to have a >>>>>>definite step-recovery behavior, which probably isn't realistic. It >>>>>>stores 115 nC when biased to 1 amp forward. The recovered charge is >>>>>>not a function of ON time, also unrealistic. >>>>>> >>>>>> >>>>>[snip] >>>>> >>>>>None of the ordinary Spice variants seem to model forward and reverse >>>>>recovery time. >>>>> >>>>>Can you provide some scope photos of forward and reverse recovery at >>>>>different current levels? >>>>> >>>>>Several papers I've run across suggest that a fairly simple subcircuit >>>>>may be possible... but, being IEEE crap, their data is naive and vague >>>>>>:-} >>>>> >>>>> ...Jim Thompson >>>> >>>>I posted some 1N914 pics, taken at four different current step levels. >>> >>>I saw those but couldn't determine the current levels... that green >>>drives my eyes nuts. >> >>The P400 DDG box display (not all that easy to read either) shows the >>VH and VL open-circuit voltages from the 50-ohm generator. The diode >>is across the transmission line from the pulse gen to the 50 ohm >>scope. There's a 20 dB attenuator on the sampling head input. >> >>So the diode sees a 25 ohm source, at half the voltage on the DDG >>display. >> >> >> >> >>> >>>> >>>>Looks sorta like constant-area overshoot. >>>> >>>>Forward recovery doesn't matter in my current application, since I'll >>>>have plenty of time to pump current into my diodes. Controlling the >>>>amount of reverse charge matters, and I need to simulate reverse >>>>recovery accurately in the higher-level simulation. >>> > > >OK. That gives me enough info to "play". > > ...Jim Thompson
When we did our DSRD pulser, we found a lot of variation in diodes that had nominally the same part number. We made a deal with Mouser to sample us diodes and, if we liked them, sell us the rest of the same reel. The best DSRD/Grehkov diode turned out the be the C-B junction of an NPN horizontal-output transistor, now obsolete. -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On 13/09/14 04:38, Phil Hobbs wrote:
> On 09/12/2014 02:31 PM, Jim Thompson wrote:
...
>> I don't even know what a Grekhov diode is :-[ >> But I'll look it up. >> ...Jim Thompson > You're in for a treat. Grekhov & Co. figured out how to make certain > types of power rectifiers into SRDs--picture a 3 kV, subnanosecond pulse > into 50 ohms from the equivalent of a 1N4007. John L described one that > he made earlier in the thread.
Tom McEwan patented a circuit which avalanched a 1N4004, producing 100KW pulses in the 100ps region. It required a 1000V step of a few ns (mosfet) followed by a PFN. I mentioned it here a few years back, and it got quite a bit of discussion including multiple posts by Win Hill, and IIRC it was after that that JL actually tried it.
On Mon, 15 Sep 2014 13:30:22 +1000, Clifford Heath
<no.spam@please.net> wrote:

>On 13/09/14 04:38, Phil Hobbs wrote: >> On 09/12/2014 02:31 PM, Jim Thompson wrote: >... >>> I don't even know what a Grekhov diode is :-[ >>> But I'll look it up. >>> ...Jim Thompson >> You're in for a treat. Grekhov & Co. figured out how to make certain >> types of power rectifiers into SRDs--picture a 3 kV, subnanosecond pulse >> into 50 ohms from the equivalent of a 1N4007. John L described one that >> he made earlier in the thread. > >Tom McEwan patented a circuit which avalanched a 1N4004, producing 100KW >pulses in the 100ps region. It required a 1000V step of a few ns >(mosfet) followed by a PFN. I mentioned it here a few years back, and it >got quite a bit of discussion including multiple posts by Win Hill, and >IIRC it was after that that JL actually tried it.
You're probably referring to a pulser that uses a DSRD (opening switch) to drive an avalanche diode (closing switch). I've done the DSRD circuit, to make 2KV at about 3 ns width, but I haven't done the avalanche stage. I was aware of the McEwan work, but my pulse generator was based on Grehkov's original papers. McEwan has an enormous number of largely silly patents. He seemed to be a patent addict. -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On 9/14/2014 11:30 PM, Clifford Heath wrote:
> On 13/09/14 04:38, Phil Hobbs wrote: >> On 09/12/2014 02:31 PM, Jim Thompson wrote: > ... >>> I don't even know what a Grekhov diode is :-[ >>> But I'll look it up. >>> ...Jim Thompson >> You're in for a treat. Grekhov & Co. figured out how to make certain >> types of power rectifiers into SRDs--picture a 3 kV, subnanosecond pulse >> into 50 ohms from the equivalent of a 1N4007. John L described one that >> he made earlier in the thread. > > Tom McEwan patented a circuit which avalanched a 1N4004, producing 100KW > pulses in the 100ps region. It required a 1000V step of a few ns > (mosfet) followed by a PFN. I mentioned it here a few years back, and it > got quite a bit of discussion including multiple posts by Win Hill, and > IIRC it was after that that JL actually tried it.
Hopefully he didn't do it during the Super Bowl, or his neighbours would have been after him with pitchforks. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
On 14/09/2014 21:31, John Larkin wrote:
> On Sun, 14 Sep 2014 13:19:21 -0700, Jim Thompson > <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: > >> On Sun, 14 Sep 2014 13:17:03 -0700, John Larkin >> <jlarkin@highlandtechnology.com> wrote: >> >>> On Sun, 14 Sep 2014 13:08:02 -0700, Jim Thompson >>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>> >>>> On Sun, 14 Sep 2014 12:53:09 -0700, John Larkin >>>> <jlarkin@highlandtechnology.com> wrote: >>>> >>>>> On Sun, 14 Sep 2014 12:44:19 -0700, Jim Thompson >>>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>>> >>>>>> On Sat, 06 Sep 2014 12:31:46 -0700, John Larkin >>>>>> <jlarkin@highlandtechnology.com> wrote: >>>>>> >>>>>>> >>>>>>> I got curious about the amount of reverse-recovery charge in PN >>>>>>> diodes, as a function of forward current (and time of fwd bias) and >>>>>>> diode size/type. >>>>>>> >>>>>>> Question is, are the LT Spice diode models realistic? We'll have to >>>>>>> test some diodes to see. Since diode recovery for a given part number >>>>>>> depends a lot on the manufacturer, we should stick to sole-source >>>>>>> parts and tweak the Spice model to align with reality. >>>>>>> >>>>>>> The ES1D below, straight from the LT Spice diode list, seems to have a >>>>>>> definite step-recovery behavior, which probably isn't realistic. It >>>>>>> stores 115 nC when biased to 1 amp forward. The recovered charge is >>>>>>> not a function of ON time, also unrealistic. >>>>>>> >>>>>>> >>>>>> [snip] >>>>>> >>>>>> None of the ordinary Spice variants seem to model forward and reverse >>>>>> recovery time. >>>>>> >>>>>> Can you provide some scope photos of forward and reverse recovery at >>>>>> different current levels? >>>>>> >>>>>> Several papers I've run across suggest that a fairly simple subcircuit >>>>>> may be possible... but, being IEEE crap, their data is naive and vague >>>>>>> :-} >>>>>> >>>>>> ...Jim Thompson >>>>> >>>>> I posted some 1N914 pics, taken at four different current step levels. >>>> >>>> I saw those but couldn't determine the current levels... that green >>>> drives my eyes nuts. >>> >>> The P400 DDG box display (not all that easy to read either) shows the >>> VH and VL open-circuit voltages from the 50-ohm generator. The diode >>> is across the transmission line from the pulse gen to the 50 ohm >>> scope. There's a 20 dB attenuator on the sampling head input. >>> >>> So the diode sees a 25 ohm source, at half the voltage on the DDG >>> display. >>> >>> >>> >>> >>>> >>>>> >>>>> Looks sorta like constant-area overshoot. >>>>> >>>>> Forward recovery doesn't matter in my current application, since I'll >>>>> have plenty of time to pump current into my diodes. Controlling the >>>>> amount of reverse charge matters, and I need to simulate reverse >>>>> recovery accurately in the higher-level simulation. >>>> >> >> >> OK. That gives me enough info to "play". >> >> ...Jim Thompson > > When we did our DSRD pulser, we found a lot of variation in diodes > that had nominally the same part number. We made a deal with Mouser to > sample us diodes and, if we liked them, sell us the rest of the same > reel. > > The best DSRD/Grehkov diode turned out the be the C-B junction of an > NPN horizontal-output transistor, now obsolete. > >
See "A Simple Diode Model with Reverse Recovery" Lauritzen and Ma (http://www.ee.washington.edu/research/pemodels/papers/simpdioderev.pdf) - this model is implemented in the Simetrix simulator.
On Wed, 10 Sep 2014 18:53:39 +0100, "Kevin Aylward"
<ExtractkevinRemove@kevinaylward.co.uk> wrote:

[snip]
> > >It is interesting that the most basic semiconductor, is actually quite >complex. On the surface,it would seem that an inductor in series would model >the increase in voltage during turn on, which it does, but it messes up the >turn off waveform. It looks like it needs to be a nonlinear inductor with >other stuff. It will have to wait till the weekend though. > > >Kevin Aylward >www.kevinaylward.co.uk >www.anasoft.co.uk - SuperSpice
It's wa-a-ay past the weekend >:-} The forward recovery _is_ trivial to model and I've figured a way to keep it from tangling with the reverse recovery... but the reverse recovery mechanism is non-trivial to model... still scratching my... ;-) ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Sat, 06 Sep 2014 12:31:46 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

> >I got curious about the amount of reverse-recovery charge in PN >diodes, as a function of forward current (and time of fwd bias) and >diode size/type. >
[snip] Does this look to be viable enough... <http://www.analog-innovations.com/SED/FwdRevRecovery_Behavioral.png> If so I'll continue and see what it takes to parameterize it to specific diodes. (100% Behavioral Modeled... 6 lines in the subcircuit >:-) ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Thu, 18 Sep 2014 10:51:45 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Sat, 06 Sep 2014 12:31:46 -0700, John Larkin ><jlarkin@highlandtechnology.com> wrote: > >> >>I got curious about the amount of reverse-recovery charge in PN >>diodes, as a function of forward current (and time of fwd bias) and >>diode size/type. >> >[snip] > >Does this look to be viable enough... > ><http://www.analog-innovations.com/SED/FwdRevRecovery_Behavioral.png> > >If so I'll continue and see what it takes to parameterize it to >specific diodes. > >(100% Behavioral Modeled... 6 lines in the subcircuit >:-) > > ...Jim Thompson
Interesting, but I just told the potential customer to jump in the nearest lake. They played the tired old trick, "we don't want to buy your products, but how would you like to be a consultant?" In other words, they want to own our IP cheap. -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com