On Thursday, August 23, 2018 at 9:34:18 AM UTC+10, George Herold wrote:
> On Wednesday, August 22, 2018 at 5:32:14 PM UTC-4, piglet wrote:
> > On 21/08/2018 20:16, George Herold wrote:
> > > On Tuesday, August 21, 2018 at 6:05:06 AM UTC-4, piglet wrote:
<snip>
> I need (maybe) a delayed reset and blanking pulse.
> I've got 74hc14s, diodes, R's and C's,
A 74HC14 isn't all that quick. There are faster flavours of CMOS around and ECLinPS is even quicker.
The faster stuff doesn't cope with large voltage swings, so you have to cascode the output into a quick transistor with a decent collector-to-emitter breakdown voltage. I dug up something suitable in a earlier thread on this subject.
> I was going to ask for links with circuits,
> but it's simple enough, (I think) I can use the RC
> delay on one side and the diode on the other.
> That still leaves a lot of permutations.
The literature was full of them.
Keeping the actual avalanche period as short as possible seems to be a good idea.
The charge carrier generation that creates and sustains the avalanche seems to dump energy into the channel, which shows up as after-pulsing, and the less of that, the better.
--
Bill Sloman, Sydney
Reply by George Herold●August 22, 20182018-08-22
On Wednesday, August 22, 2018 at 5:32:14 PM UTC-4, piglet wrote:
> On 21/08/2018 20:16, George Herold wrote:
> > On Tuesday, August 21, 2018 at 6:05:06 AM UTC-4, piglet wrote:
big snip
> > George H.
> > ps
> > I've been f-ing around today trying to go from measuring 'dc' photo current
> > (in my SPAD as only APD) to photon counting. But it's a bit of a hard hill
> > to get over. If I have a maximum count rate of 1e6 that's ~0.1pA..
> > (e~ 1e-19) and APD gain of 100 gives me 10 pA. Not very much, and I'm
> > grubbing around in dark currents/ offset voltages and bias currents.
> >
> > GH
> >
>
> Since all you want is to replensish a little bit of lost charge I wonder
> if it can be done from the low side with a small capacitor?
Yeah I think that's Mario's (see paper's upstream) first low
side quench and reset circuit. He pulses in some charge
through a cap. It's a diode and he takes advantage of that.
(sometimes my model of a diode is a switch, and that stops
me from thinking in reverse. :^)
Then my power supply has to swallow the reverse over-voltage?
>
> John Larkin's resistor pullup to EHV clamped to the working voltage is
> gloriously simple.
Umm, I don't know/ recall it.
>
> piglet
I need (maybe) a delayed reset and blanking pulse.
I've got 74hc14s, diodes, R's and C's,
I was going to ask for links with circuits,
but it's simple enough, (I think) I can use the RC
delay on one side and the diode on the other.
That still leaves a lot of permutations.
George H.
Reply by piglet●August 22, 20182018-08-22
On 21/08/2018 20:16, George Herold wrote:
> On Tuesday, August 21, 2018 at 6:05:06 AM UTC-4, piglet wrote:
>> On 21/08/2018 01:28, George Herold wrote:
>>> On Monday, August 20, 2018 at 4:13:28 PM UTC-4, piglet wrote:
>>>> On 19/08/2018 20:20, George Herold wrote:
>>>>> On Sunday, August 19, 2018 at 9:07:04 AM UTC-4, piglet wrote:
>>>>>> On 19/08/2018 03:10, George Herold wrote:
>>>>>>> On Saturday, August 18, 2018 at 2:40:03 PM UTC-4, piglet wrote:
>>>>>>>> On 17/08/2018 17:09, George Herold wrote:
>>>>>>>>> Hi All, well one last swing at my HV reset spad circuit. (circuit
>>>>>>>>> scribble or spice file on request.) I need a low input C, P-fet with
>>>>>>>>> decent Vds (~40V or greater.)* (It needs to turn off fast (<50ns),
>>>>>>>>> some pfets look to have built in gate resistors for safety and these
>>>>>>>>> are slower.)
>>>>>>>>>
>>>>>>>>> Anyway at the moment I've got the BSS84 from infineon
>>>>>>>>> https://www.infineon.com/dgdl/Infineon-BSS84PW-DS-v01_05-en.pdf?fileId=db3a3043321e49940132482056d32474
>>>>>>>>>
>>>>>>>>> And the Si1021 from Vishay
>>>>>>>>> http://www.vishay.com/docs/71410/71410.pdf
>>>>>>>>>
>>>>>>>>> Do you have another suggestion that I should put on my shopping list?
>>>>>>>>>
>>>>>>>>> Say, everyone seems to make a BSS84 with slightly different specs...
>>>>>>>>> what's up with that?
>>>>>>>>>
>>>>>>>>> Oh at the moment this is running with a VP0106. (60 pF Cin)
>>>>>>>>> This is with dummy load, (3.3 pF cap)
>>>>>>>>> Chan. 1 is gate voltage,
>>>>>>>>> Chan. 2 is HV on top of cap, about 20V reset (not to scale)
>>>>>>>>>
>>>>>>>>> https://www.dropbox.com/s/cmfsjbgiyo3b255/pfet-rst.BMP?dl=0
>>>>>>>>>
>>>>>>>>> George H.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> *If there was a much better N-FET, I could flip the whole thing over and run
>>>>>>>>> it from a negative HV supply.
>>>>>>>>>
>>>>>>>>
>>>>>>>> If I read the scope right looks like the gate drive slews to -4V in
>>>>>>>> 20ns, which if your 60pF Cin is used then grossly simplified I make the
>>>>>>>> gate drive current a mere 12mA.
>>>>>>> I think less (Dang I should have put my spice sim in drop box.)
>>>>>>> I'm a brute force type. (subtle takes experience)
>>>>>>> The p-fet's source is.. (there are some 1nF and 10nF not shown)
>>>>>>>
>>>>>>> HV---+---1mA limit---+--------+
>>>>>>> | | |
>>>>>>> 0.1mA lim. | R4 500
>>>>>>> | | S |
>>>>>>> +-----------------+| +---+
>>>>>>> | | | | |
>>>>>>> R1 400k 1M? R2 | | |
>>>>>>> | | +| |
>>>>>>> +--+--|<--|<--|<---+ + D |
>>>>>>> | | | |
>>>>>>> R5 C 3.3pF 2M? R3 \ |
>>>>>>> 4M | | \|
>>>>>>> +--+-Gnd Gnd |--4V
>>>>>>> /|
>>>>>>> sig gen.-74hc14 x6 ---R6 100--< |
>>>>>>>
>>>>>>> The diodes are 1n5711 Schottky.
>>>>>>> (I don't need three anymore.)
>>>>>>> The C is my spad and R5 leaks off some voltage.
>>>>>>>
>>>>>>> I get about 25 mA through R6, which give me ~10 Vgs if
>>>>>>> I pulse it for a long time. (1-200ns)
>>>>>>>
>>>>>>> My big time suck is R4 and Cin..
>>>>>>> Say if I stuck the right amount of L in series with
>>>>>>> R4, would that get the gate on sooner and off faster?
>>>>>>>
>>>>>>> George H.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> Also looks like the drain doesnt do much till gate hits 3.5V so if you
>>>>>>>> can increase the gate drive voltage, sharpen it and make it stiffer then
>>>>>>>> you'd get closer to your target?
>>>>>>>>
>>>>>>>> piglet
>>>>>>>
>>>>>>
>>>>>> Not sure I understand the circuit, do you have the P-fet normally ON and
>>>>>> want to switch it off rapidly or do you have the fet normally OFF and
>>>>>> want to switch it on rapidly. What is the desired action?
>>>>> Normally off.. it is getting a bit byzantine.
>>>>> I'm sorta blowing ~30mA on the gate to switch 3 mA across R1.
>>>>>
>>>>>>
>>>>>> Does that 1mA limit fight your gate drive or are there bypass caps
>>>>>> capable of supporting brief current draws?
>>>>> Yeah bypass caps not shown, 1nF on backside of 0.1mA limit and
>>>>> 10nF behind 1mA .
>>>>>>
>>>>>> Looks like source and gate resistor R4 return to different points which
>>>>>> could exceed Vgs?
>>>>> I hadn't thought about the separate limits turning on at different times
>>>>> and blowing the pfet, so I owe you another beer, or beverage of your choice.
>>>>>
>>>>> George H.
>>>>>
>>>>>>
>>>>>> piglet
>>>>>
>>>>
>>>> What do want the pfet turning on to do to your SPAD? Looks like it
>>>> doesn't do anything to reduce the spad bias if I read the ascii art
>>>> correctly - are those diodes right?
>>>>
>>>> piglet
>>>
>>> Right, when the spad fires, all it's over voltage charge goes away.
>>> (~10-20 V over-voltage) It then takes a long time to recharge through
>>> the 400k R. (this large value 'self-quenches' the avalanche)
>>> The pfet is to speed up the recharge time...
>>> you posted some nice circuits that both quenched and recharged,
>>> I may have to do that.. But this keeps the quench and reset separate.
>>> I don't understand how the self-quench works, so I figured it might be nice
>>> to keep it separate.
>>>
>>> Yeah diodes are right, they are meant to shield the spad C from the switch
>>> C. I figure I'll put another sting on the other side,
>>> same voltage drop.
>>>
>>> George H.
>>>
>>
>> Thanks, now I see. I never considered that way of speeding up recharge.
>>
>> BTW I had a go at simulating an off-the-peg step up transformer quench,
>> get 30V dip in 19ns but I think that can be improved. See below:
>>
> <snipping LTspice circuit>
> OK thanks... I may still have to give that a try.
>
> Hey adding a bit of inductor helped some.
> (matching times.. RC= L/R)
>
> Here's my spice file.
>
> Version 4
> SHEET 1 880 680
> WIRE -256 -160 -336 -160
> WIRE -176 -160 -256 -160
> WIRE 96 -160 -176 -160
> WIRE 192 -160 96 -160
> WIRE 336 -160 304 -160
> WIRE 464 -160 416 -160
> WIRE 592 -160 464 -160
> WIRE 304 -128 304 -160
> WIRE 464 -128 464 -160
> WIRE 592 -128 592 -160
> WIRE -176 -112 -176 -160
> WIRE 96 -112 96 -160
> WIRE -336 -64 -336 -160
> WIRE 192 -48 192 -80
> WIRE 256 -32 240 -32
> WIRE -176 0 -176 -32
> WIRE -128 0 -176 0
> WIRE -96 0 -128 0
> WIRE -64 0 -96 0
> WIRE 256 0 256 -32
> WIRE 304 0 304 -48
> WIRE 304 0 256 0
> WIRE 304 32 304 0
> WIRE 368 32 368 16
> WIRE 368 32 304 32
> WIRE -336 48 -336 16
> WIRE -176 48 -176 0
> WIRE -96 48 -96 0
> WIRE 96 48 96 -32
> WIRE 160 48 96 48
> WIRE 304 48 304 32
> WIRE 0 64 0 0
> WIRE 64 112 64 64
> WIRE 160 112 160 48
> WIRE 160 112 128 112
> WIRE 192 112 192 48
> WIRE 192 112 160 112
> WIRE 624 112 400 112
> WIRE 192 128 192 112
> WIRE -176 144 -176 128
> WIRE -96 144 -96 112
> WIRE -96 144 -176 144
> WIRE 304 160 304 128
> WIRE -176 176 -176 144
> WIRE 400 208 400 192
> WIRE 400 208 368 208
> WIRE 96 224 -192 224
> WIRE 400 224 400 208
> WIRE 496 224 400 224
> WIRE 624 224 624 112
> WIRE 400 272 400 224
> WIRE 96 320 96 224
> WIRE 176 320 96 320
> WIRE 304 320 304 256
> WIRE 304 320 256 320
> WIRE -192 336 -192 304
> WIRE 496 352 496 288
> WIRE 496 352 400 352
> WIRE 624 352 624 304
> WIRE 624 352 496 352
> WIRE 624 400 624 352
> FLAG -192 336 0
> FLAG -336 48 0
> FLAG 624 400 0
> FLAG -176 176 0
> FLAG 192 208 0
> FLAG -256 -96 0
> FLAG 304 384 0
> FLAG 368 16 Vgate
> FLAG -128 0 Vspad
> FLAG 592 -48 0
> FLAG 464 -64 0
> SYMBOL npn2 368 160 M0
> SYMATTR InstName Q1
> SYMATTR Value 2N5550
> SYMBOL voltage -192 208 R0
> WINDOW 3 -451 58 Left 2
> WINDOW 123 0 0 Left 2
> WINDOW 39 0 0 Left 2
> SYMATTR Value PULSE(5 .5 20n 3n 3n 10n 500n 2)
> SYMATTR InstName V1
> SYMBOL voltage -336 -80 R0
> WINDOW 123 0 0 Left 2
> WINDOW 39 0 0 Left 2
> SYMATTR InstName V2
> SYMATTR Value 101V
> SYMBOL voltage 624 208 R0
> WINDOW 123 0 0 Left 2
> WINDOW 39 0 0 Left 2
> SYMATTR InstName V3
> SYMATTR Value 5V
> SYMBOL res 384 96 R0
> SYMATTR InstName R1
> SYMATTR Value 1k
> SYMBOL res 384 256 R0
> SYMATTR InstName R2
> SYMATTR Value 4k
> SYMBOL res 288 32 R0
> SYMATTR InstName R3
> SYMATTR Value 10
> SYMBOL res 272 304 R90
> WINDOW 0 0 56 VBottom 2
> WINDOW 3 32 56 VTop 2
> SYMATTR InstName R4
> SYMATTR Value 100
> SYMBOL res 288 -144 R0
> WINDOW 3 79 43 Left 2
> SYMATTR Value 300
> SYMATTR InstName R5
> SYMBOL res 176 -176 R0
> SYMATTR InstName R6
> SYMATTR Value 1
> SYMBOL res -192 -128 R0
> SYMATTR InstName R7
> SYMATTR Value 500k
> SYMBOL res -192 32 R0
> SYMATTR InstName R8
> SYMATTR Value 5meg
> SYMBOL cap -112 48 R0
> SYMATTR InstName C1
> SYMATTR Value 3p
> SYMBOL cap 480 224 R0
> SYMATTR InstName C2
> SYMATTR Value 1n
> SYMBOL diode 0 -16 R90
> WINDOW 0 0 32 VBottom 2
> WINDOW 3 32 32 VTop 2
> SYMATTR InstName D1
> SYMATTR Value 1N4148
> SYMBOL diode 64 48 R90
> WINDOW 0 0 32 VBottom 2
> WINDOW 3 32 32 VTop 2
> SYMATTR InstName D2
> SYMATTR Value 1N4148
> SYMBOL diode 128 96 R90
> WINDOW 0 0 32 VBottom 2
> WINDOW 3 32 32 VTop 2
> SYMATTR InstName D3
> SYMATTR Value 1N4148
> SYMBOL res 176 112 R0
> SYMATTR InstName R9
> SYMATTR Value 10meg
> SYMBOL cap -272 -160 R0
> SYMATTR InstName C3
> SYMATTR Value 1n
> SYMBOL pmos 240 48 R180
> SYMATTR InstName M1
> SYMATTR Value BSS84
> SYMBOL res 80 -128 R0
> WINDOW 0 -57 13 Left 2
> WINDOW 3 -81 58 Left 2
> SYMATTR InstName R10
> SYMATTR Value 2meg
> SYMBOL voltage 592 -144 R0
> WINDOW 123 0 0 Left 2
> WINDOW 39 0 0 Left 2
> SYMATTR InstName V4
> SYMATTR Value 100v
> SYMBOL cap 448 -128 R0
> SYMATTR InstName C4
> SYMATTR Value 10nF
> SYMBOL ind 432 -176 R90
> WINDOW 0 5 56 VBottom 2
> WINDOW 3 -27 3 VTop 2
> SYMATTR InstName L1
> SYMATTR Value 3µ
> TEXT -648 424 Left 2 !.tran 0 600n 0
>
>
> George H.
> ps
> I've been f-ing around today trying to go from measuring 'dc' photo current
> (in my SPAD as only APD) to photon counting. But it's a bit of a hard hill
> to get over. If I have a maximum count rate of 1e6 that's ~0.1pA..
> (e~ 1e-19) and APD gain of 100 gives me 10 pA. Not very much, and I'm
> grubbing around in dark currents/ offset voltages and bias currents.
>
> GH
>
Since all you want is to replensish a little bit of lost charge I wonder
if it can be done from the low side with a small capacitor?
John Larkin's resistor pullup to EHV clamped to the working voltage is
gloriously simple.
piglet
Reply by George Herold●August 21, 20182018-08-21
On Tuesday, August 21, 2018 at 6:05:06 AM UTC-4, piglet wrote:
> On 21/08/2018 01:28, George Herold wrote:
> > On Monday, August 20, 2018 at 4:13:28 PM UTC-4, piglet wrote:
> >> On 19/08/2018 20:20, George Herold wrote:
> >>> On Sunday, August 19, 2018 at 9:07:04 AM UTC-4, piglet wrote:
> >>>> On 19/08/2018 03:10, George Herold wrote:
> >>>>> On Saturday, August 18, 2018 at 2:40:03 PM UTC-4, piglet wrote:
> >>>>>> On 17/08/2018 17:09, George Herold wrote:
> >>>>>>> Hi All, well one last swing at my HV reset spad circuit. (circuit
> >>>>>>> scribble or spice file on request.) I need a low input C, P-fet with
> >>>>>>> decent Vds (~40V or greater.)* (It needs to turn off fast (<50ns),
> >>>>>>> some pfets look to have built in gate resistors for safety and these
> >>>>>>> are slower.)
> >>>>>>>
> >>>>>>> Anyway at the moment I've got the BSS84 from infineon
> >>>>>>> https://www.infineon.com/dgdl/Infineon-BSS84PW-DS-v01_05-en.pdf?fileId=db3a3043321e49940132482056d32474
> >>>>>>>
> >>>>>>> And the Si1021 from Vishay
> >>>>>>> http://www.vishay.com/docs/71410/71410.pdf
> >>>>>>>
> >>>>>>> Do you have another suggestion that I should put on my shopping list?
> >>>>>>>
> >>>>>>> Say, everyone seems to make a BSS84 with slightly different specs...
> >>>>>>> what's up with that?
> >>>>>>>
> >>>>>>> Oh at the moment this is running with a VP0106. (60 pF Cin)
> >>>>>>> This is with dummy load, (3.3 pF cap)
> >>>>>>> Chan. 1 is gate voltage,
> >>>>>>> Chan. 2 is HV on top of cap, about 20V reset (not to scale)
> >>>>>>>
> >>>>>>> https://www.dropbox.com/s/cmfsjbgiyo3b255/pfet-rst.BMP?dl=0
> >>>>>>>
> >>>>>>> George H.
> >>>>>>>
> >>>>>>>
> >>>>>>> *If there was a much better N-FET, I could flip the whole thing over and run
> >>>>>>> it from a negative HV supply.
> >>>>>>>
> >>>>>>
> >>>>>> If I read the scope right looks like the gate drive slews to -4V in
> >>>>>> 20ns, which if your 60pF Cin is used then grossly simplified I make the
> >>>>>> gate drive current a mere 12mA.
> >>>>> I think less (Dang I should have put my spice sim in drop box.)
> >>>>> I'm a brute force type. (subtle takes experience)
> >>>>> The p-fet's source is.. (there are some 1nF and 10nF not shown)
> >>>>>
> >>>>> HV---+---1mA limit---+--------+
> >>>>> | | |
> >>>>> 0.1mA lim. | R4 500
> >>>>> | | S |
> >>>>> +-----------------+| +---+
> >>>>> | | | | |
> >>>>> R1 400k 1M? R2 | | |
> >>>>> | | +| |
> >>>>> +--+--|<--|<--|<---+ + D |
> >>>>> | | | |
> >>>>> R5 C 3.3pF 2M? R3 \ |
> >>>>> 4M | | \|
> >>>>> +--+-Gnd Gnd |--4V
> >>>>> /|
> >>>>> sig gen.-74hc14 x6 ---R6 100--< |
> >>>>>
> >>>>> The diodes are 1n5711 Schottky.
> >>>>> (I don't need three anymore.)
> >>>>> The C is my spad and R5 leaks off some voltage.
> >>>>>
> >>>>> I get about 25 mA through R6, which give me ~10 Vgs if
> >>>>> I pulse it for a long time. (1-200ns)
> >>>>>
> >>>>> My big time suck is R4 and Cin..
> >>>>> Say if I stuck the right amount of L in series with
> >>>>> R4, would that get the gate on sooner and off faster?
> >>>>>
> >>>>> George H.
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>>
> >>>>>> Also looks like the drain doesnt do much till gate hits 3.5V so if you
> >>>>>> can increase the gate drive voltage, sharpen it and make it stiffer then
> >>>>>> you'd get closer to your target?
> >>>>>>
> >>>>>> piglet
> >>>>>
> >>>>
> >>>> Not sure I understand the circuit, do you have the P-fet normally ON and
> >>>> want to switch it off rapidly or do you have the fet normally OFF and
> >>>> want to switch it on rapidly. What is the desired action?
> >>> Normally off.. it is getting a bit byzantine.
> >>> I'm sorta blowing ~30mA on the gate to switch 3 mA across R1.
> >>>
> >>>>
> >>>> Does that 1mA limit fight your gate drive or are there bypass caps
> >>>> capable of supporting brief current draws?
> >>> Yeah bypass caps not shown, 1nF on backside of 0.1mA limit and
> >>> 10nF behind 1mA .
> >>>>
> >>>> Looks like source and gate resistor R4 return to different points which
> >>>> could exceed Vgs?
> >>> I hadn't thought about the separate limits turning on at different times
> >>> and blowing the pfet, so I owe you another beer, or beverage of your choice.
> >>>
> >>> George H.
> >>>
> >>>>
> >>>> piglet
> >>>
> >>
> >> What do want the pfet turning on to do to your SPAD? Looks like it
> >> doesn't do anything to reduce the spad bias if I read the ascii art
> >> correctly - are those diodes right?
> >>
> >> piglet
> >
> > Right, when the spad fires, all it's over voltage charge goes away.
> > (~10-20 V over-voltage) It then takes a long time to recharge through
> > the 400k R. (this large value 'self-quenches' the avalanche)
> > The pfet is to speed up the recharge time...
> > you posted some nice circuits that both quenched and recharged,
> > I may have to do that.. But this keeps the quench and reset separate.
> > I don't understand how the self-quench works, so I figured it might be nice
> > to keep it separate.
> >
> > Yeah diodes are right, they are meant to shield the spad C from the switch
> > C. I figure I'll put another sting on the other side,
> > same voltage drop.
> >
> > George H.
> >
>
> Thanks, now I see. I never considered that way of speeding up recharge.
>
> BTW I had a go at simulating an off-the-peg step up transformer quench,
> get 30V dip in 19ns but I think that can be improved. See below:
>
<snipping LTspice circuit>
OK thanks... I may still have to give that a try.
Hey adding a bit of inductor helped some.
(matching times.. RC= L/R)
Here's my spice file.
Version 4
SHEET 1 880 680
WIRE -256 -160 -336 -160
WIRE -176 -160 -256 -160
WIRE 96 -160 -176 -160
WIRE 192 -160 96 -160
WIRE 336 -160 304 -160
WIRE 464 -160 416 -160
WIRE 592 -160 464 -160
WIRE 304 -128 304 -160
WIRE 464 -128 464 -160
WIRE 592 -128 592 -160
WIRE -176 -112 -176 -160
WIRE 96 -112 96 -160
WIRE -336 -64 -336 -160
WIRE 192 -48 192 -80
WIRE 256 -32 240 -32
WIRE -176 0 -176 -32
WIRE -128 0 -176 0
WIRE -96 0 -128 0
WIRE -64 0 -96 0
WIRE 256 0 256 -32
WIRE 304 0 304 -48
WIRE 304 0 256 0
WIRE 304 32 304 0
WIRE 368 32 368 16
WIRE 368 32 304 32
WIRE -336 48 -336 16
WIRE -176 48 -176 0
WIRE -96 48 -96 0
WIRE 96 48 96 -32
WIRE 160 48 96 48
WIRE 304 48 304 32
WIRE 0 64 0 0
WIRE 64 112 64 64
WIRE 160 112 160 48
WIRE 160 112 128 112
WIRE 192 112 192 48
WIRE 192 112 160 112
WIRE 624 112 400 112
WIRE 192 128 192 112
WIRE -176 144 -176 128
WIRE -96 144 -96 112
WIRE -96 144 -176 144
WIRE 304 160 304 128
WIRE -176 176 -176 144
WIRE 400 208 400 192
WIRE 400 208 368 208
WIRE 96 224 -192 224
WIRE 400 224 400 208
WIRE 496 224 400 224
WIRE 624 224 624 112
WIRE 400 272 400 224
WIRE 96 320 96 224
WIRE 176 320 96 320
WIRE 304 320 304 256
WIRE 304 320 256 320
WIRE -192 336 -192 304
WIRE 496 352 496 288
WIRE 496 352 400 352
WIRE 624 352 624 304
WIRE 624 352 496 352
WIRE 624 400 624 352
FLAG -192 336 0
FLAG -336 48 0
FLAG 624 400 0
FLAG -176 176 0
FLAG 192 208 0
FLAG -256 -96 0
FLAG 304 384 0
FLAG 368 16 Vgate
FLAG -128 0 Vspad
FLAG 592 -48 0
FLAG 464 -64 0
SYMBOL npn2 368 160 M0
SYMATTR InstName Q1
SYMATTR Value 2N5550
SYMBOL voltage -192 208 R0
WINDOW 3 -451 58 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value PULSE(5 .5 20n 3n 3n 10n 500n 2)
SYMATTR InstName V1
SYMBOL voltage -336 -80 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value 101V
SYMBOL voltage 624 208 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value 5V
SYMBOL res 384 96 R0
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res 384 256 R0
SYMATTR InstName R2
SYMATTR Value 4k
SYMBOL res 288 32 R0
SYMATTR InstName R3
SYMATTR Value 10
SYMBOL res 272 304 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 100
SYMBOL res 288 -144 R0
WINDOW 3 79 43 Left 2
SYMATTR Value 300
SYMATTR InstName R5
SYMBOL res 176 -176 R0
SYMATTR InstName R6
SYMATTR Value 1
SYMBOL res -192 -128 R0
SYMATTR InstName R7
SYMATTR Value 500k
SYMBOL res -192 32 R0
SYMATTR InstName R8
SYMATTR Value 5meg
SYMBOL cap -112 48 R0
SYMATTR InstName C1
SYMATTR Value 3p
SYMBOL cap 480 224 R0
SYMATTR InstName C2
SYMATTR Value 1n
SYMBOL diode 0 -16 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 64 48 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL diode 128 96 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D3
SYMATTR Value 1N4148
SYMBOL res 176 112 R0
SYMATTR InstName R9
SYMATTR Value 10meg
SYMBOL cap -272 -160 R0
SYMATTR InstName C3
SYMATTR Value 1n
SYMBOL pmos 240 48 R180
SYMATTR InstName M1
SYMATTR Value BSS84
SYMBOL res 80 -128 R0
WINDOW 0 -57 13 Left 2
WINDOW 3 -81 58 Left 2
SYMATTR InstName R10
SYMATTR Value 2meg
SYMBOL voltage 592 -144 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V4
SYMATTR Value 100v
SYMBOL cap 448 -128 R0
SYMATTR InstName C4
SYMATTR Value 10nF
SYMBOL ind 432 -176 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 -27 3 VTop 2
SYMATTR InstName L1
SYMATTR Value 3µ
TEXT -648 424 Left 2 !.tran 0 600n 0
George H.
ps
I've been f-ing around today trying to go from measuring 'dc' photo current
(in my SPAD as only APD) to photon counting. But it's a bit of a hard hill
to get over. If I have a maximum count rate of 1e6 that's ~0.1pA..
(e~ 1e-19) and APD gain of 100 gives me 10 pA. Not very much, and I'm
grubbing around in dark currents/ offset voltages and bias currents.
GH
Reply by piglet●August 21, 20182018-08-21
On 21/08/2018 01:28, George Herold wrote:
> On Monday, August 20, 2018 at 4:13:28 PM UTC-4, piglet wrote:
>> On 19/08/2018 20:20, George Herold wrote:
>>> On Sunday, August 19, 2018 at 9:07:04 AM UTC-4, piglet wrote:
>>>> On 19/08/2018 03:10, George Herold wrote:
>>>>> On Saturday, August 18, 2018 at 2:40:03 PM UTC-4, piglet wrote:
>>>>>> On 17/08/2018 17:09, George Herold wrote:
>>>>>>> Hi All, well one last swing at my HV reset spad circuit. (circuit
>>>>>>> scribble or spice file on request.) I need a low input C, P-fet with
>>>>>>> decent Vds (~40V or greater.)* (It needs to turn off fast (<50ns),
>>>>>>> some pfets look to have built in gate resistors for safety and these
>>>>>>> are slower.)
>>>>>>>
>>>>>>> Anyway at the moment I've got the BSS84 from infineon
>>>>>>> https://www.infineon.com/dgdl/Infineon-BSS84PW-DS-v01_05-en.pdf?fileId=db3a3043321e49940132482056d32474
>>>>>>>
>>>>>>> And the Si1021 from Vishay
>>>>>>> http://www.vishay.com/docs/71410/71410.pdf
>>>>>>>
>>>>>>> Do you have another suggestion that I should put on my shopping list?
>>>>>>>
>>>>>>> Say, everyone seems to make a BSS84 with slightly different specs...
>>>>>>> what's up with that?
>>>>>>>
>>>>>>> Oh at the moment this is running with a VP0106. (60 pF Cin)
>>>>>>> This is with dummy load, (3.3 pF cap)
>>>>>>> Chan. 1 is gate voltage,
>>>>>>> Chan. 2 is HV on top of cap, about 20V reset (not to scale)
>>>>>>>
>>>>>>> https://www.dropbox.com/s/cmfsjbgiyo3b255/pfet-rst.BMP?dl=0
>>>>>>>
>>>>>>> George H.
>>>>>>>
>>>>>>>
>>>>>>> *If there was a much better N-FET, I could flip the whole thing over and run
>>>>>>> it from a negative HV supply.
>>>>>>>
>>>>>>
>>>>>> If I read the scope right looks like the gate drive slews to -4V in
>>>>>> 20ns, which if your 60pF Cin is used then grossly simplified I make the
>>>>>> gate drive current a mere 12mA.
>>>>> I think less (Dang I should have put my spice sim in drop box.)
>>>>> I'm a brute force type. (subtle takes experience)
>>>>> The p-fet's source is.. (there are some 1nF and 10nF not shown)
>>>>>
>>>>> HV---+---1mA limit---+--------+
>>>>> | | |
>>>>> 0.1mA lim. | R4 500
>>>>> | | S |
>>>>> +-----------------+| +---+
>>>>> | | | | |
>>>>> R1 400k 1M? R2 | | |
>>>>> | | +| |
>>>>> +--+--|<--|<--|<---+ + D |
>>>>> | | | |
>>>>> R5 C 3.3pF 2M? R3 \ |
>>>>> 4M | | \|
>>>>> +--+-Gnd Gnd |--4V
>>>>> /|
>>>>> sig gen.-74hc14 x6 ---R6 100--< |
>>>>>
>>>>> The diodes are 1n5711 Schottky.
>>>>> (I don't need three anymore.)
>>>>> The C is my spad and R5 leaks off some voltage.
>>>>>
>>>>> I get about 25 mA through R6, which give me ~10 Vgs if
>>>>> I pulse it for a long time. (1-200ns)
>>>>>
>>>>> My big time suck is R4 and Cin..
>>>>> Say if I stuck the right amount of L in series with
>>>>> R4, would that get the gate on sooner and off faster?
>>>>>
>>>>> George H.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>
>>>>>> Also looks like the drain doesnt do much till gate hits 3.5V so if you
>>>>>> can increase the gate drive voltage, sharpen it and make it stiffer then
>>>>>> you'd get closer to your target?
>>>>>>
>>>>>> piglet
>>>>>
>>>>
>>>> Not sure I understand the circuit, do you have the P-fet normally ON and
>>>> want to switch it off rapidly or do you have the fet normally OFF and
>>>> want to switch it on rapidly. What is the desired action?
>>> Normally off.. it is getting a bit byzantine.
>>> I'm sorta blowing ~30mA on the gate to switch 3 mA across R1.
>>>
>>>>
>>>> Does that 1mA limit fight your gate drive or are there bypass caps
>>>> capable of supporting brief current draws?
>>> Yeah bypass caps not shown, 1nF on backside of 0.1mA limit and
>>> 10nF behind 1mA .
>>>>
>>>> Looks like source and gate resistor R4 return to different points which
>>>> could exceed Vgs?
>>> I hadn't thought about the separate limits turning on at different times
>>> and blowing the pfet, so I owe you another beer, or beverage of your choice.
>>>
>>> George H.
>>>
>>>>
>>>> piglet
>>>
>>
>> What do want the pfet turning on to do to your SPAD? Looks like it
>> doesn't do anything to reduce the spad bias if I read the ascii art
>> correctly - are those diodes right?
>>
>> piglet
>
> Right, when the spad fires, all it's over voltage charge goes away.
> (~10-20 V over-voltage) It then takes a long time to recharge through
> the 400k R. (this large value 'self-quenches' the avalanche)
> The pfet is to speed up the recharge time...
> you posted some nice circuits that both quenched and recharged,
> I may have to do that.. But this keeps the quench and reset separate.
> I don't understand how the self-quench works, so I figured it might be nice
> to keep it separate.
>
> Yeah diodes are right, they are meant to shield the spad C from the switch
> C. I figure I'll put another sting on the other side,
> same voltage drop.
>
> George H.
>
Thanks, now I see. I never considered that way of speeding up recharge.
BTW I had a go at simulating an off-the-peg step up transformer quench,
get 30V dip in 19ns but I think that can be improved. See below:
Version 4
SHEET 1 980 680
WIRE -592 -768 -848 -768
WIRE -592 -736 -592 -768
WIRE -592 -624 -592 -656
WIRE -464 -624 -592 -624
WIRE -368 -624 -464 -624
WIRE -368 -576 -368 -624
WIRE -352 -576 -368 -576
WIRE -272 -576 -288 -576
WIRE -256 -576 -272 -576
WIRE -176 -576 -192 -576
WIRE -160 -576 -176 -576
WIRE -80 -576 -96 -576
WIRE -64 -576 -80 -576
WIRE 16 -576 0 -576
WIRE 80 -576 16 -576
WIRE 208 -576 144 -576
WIRE 288 -576 208 -576
WIRE -592 -560 -592 -624
WIRE -464 -560 -464 -624
WIRE 288 -560 288 -576
WIRE -272 -528 -272 -576
WIRE -272 -528 -320 -528
WIRE -176 -528 -176 -576
WIRE -176 -528 -208 -528
WIRE -80 -528 -80 -576
WIRE -80 -528 -128 -528
WIRE 16 -528 16 -576
WIRE 16 -528 -32 -528
WIRE -368 -512 -368 -576
WIRE -272 -512 -272 -528
WIRE -176 -512 -176 -528
WIRE -80 -512 -80 -528
WIRE 16 -512 16 -528
WIRE 208 -512 208 -576
WIRE -592 -448 -592 -496
WIRE -464 -432 -464 -496
WIRE -368 -400 -368 -432
WIRE -320 -400 -320 -528
WIRE -320 -400 -368 -400
WIRE -272 -400 -272 -432
WIRE -208 -400 -208 -528
WIRE -208 -400 -272 -400
WIRE -176 -400 -176 -432
WIRE -128 -400 -128 -528
WIRE -128 -400 -176 -400
WIRE -80 -400 -80 -432
WIRE -32 -400 -32 -528
WIRE -32 -400 -80 -400
WIRE -464 -336 -464 -368
WIRE -368 -336 -368 -400
WIRE -368 -336 -464 -336
WIRE -352 -336 -368 -336
WIRE -272 -336 -272 -400
WIRE -272 -336 -288 -336
WIRE -256 -336 -272 -336
WIRE -176 -336 -176 -400
WIRE -176 -336 -192 -336
WIRE -160 -336 -176 -336
WIRE -80 -336 -80 -400
WIRE -80 -336 -96 -336
WIRE -64 -336 -80 -336
WIRE 16 -336 16 -432
WIRE 16 -336 0 -336
WIRE 48 -336 16 -336
WIRE 80 -336 48 -336
WIRE 208 -336 208 -432
WIRE 208 -336 144 -336
WIRE 208 -288 208 -336
WIRE -384 -256 -528 -256
WIRE 48 -256 48 -336
WIRE 48 -256 -384 -256
WIRE -848 -208 -848 -768
WIRE -528 -176 -528 -256
WIRE -384 -160 -384 -256
WIRE 208 -160 208 -208
WIRE -848 -16 -848 -128
WIRE -528 -16 -528 -96
WIRE -384 -16 -384 -96
WIRE 208 0 208 -80
FLAG 208 0 0
FLAG -848 -16 0
FLAG -592 -448 0
FLAG -528 -16 0
FLAG -384 -16 0
FLAG 288 -560 0
SYMBOL voltage -848 -224 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 200
SYMBOL voltage 208 -176 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value PULSE(0 -5.5 100n 1.5n 1.5n 20n)
SYMBOL cap -400 -160 R0
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res -544 -192 R0
SYMATTR InstName R1
SYMATTR Value 4meg
SYMBOL res -608 -752 R0
SYMATTR InstName R2
SYMATTR Value 100k
SYMBOL cap -608 -560 R0
SYMATTR InstName C2
SYMATTR Value 1n
SYMBOL ind2 -384 -528 R0
SYMATTR InstName L1
SYMATTR Value 3µ
SYMATTR Type ind
SYMATTR SpiceLine Rser=0.04
SYMBOL ind2 -288 -528 R0
SYMATTR InstName L2
SYMATTR Value 3µ
SYMATTR Type ind
SYMATTR SpiceLine Rser=0.04
SYMBOL ind2 -192 -528 R0
WINDOW 3 48 96 Left 2
SYMATTR Value 3µ
SYMATTR InstName L3
SYMATTR Type ind
SYMATTR SpiceLine Rser=0.04
SYMBOL ind2 -96 -528 R0
SYMATTR InstName L4
SYMATTR Value 3µ
SYMATTR Type ind
SYMATTR SpiceLine Rser=0.04
SYMBOL ind2 0 -528 R0
SYMATTR InstName L5
SYMATTR Value 3µ
SYMATTR Type ind
SYMATTR SpiceLine Rser=0.04
SYMBOL ind2 192 -528 R0
SYMATTR InstName L6
SYMATTR Value 3µ
SYMATTR Type ind
SYMATTR SpiceLine Rser=0.04
SYMBOL cap -288 -352 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 10p
SYMBOL cap -192 -352 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C4
SYMATTR Value 10p
SYMBOL cap -96 -352 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 10p
SYMBOL cap 0 -352 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C6
SYMATTR Value 10p
SYMBOL cap 144 -352 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C7
SYMATTR Value 10p
SYMBOL cap 144 -592 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C8
SYMATTR Value 10p
SYMBOL cap 0 -592 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C9
SYMATTR Value 10p
SYMBOL cap -96 -592 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C10
SYMATTR Value 10p
SYMBOL cap -192 -592 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C11
SYMATTR Value 10p
SYMBOL cap -288 -592 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C12
SYMATTR Value 10p
SYMBOL res 192 -304 R0
SYMATTR InstName R3
SYMATTR Value 10
SYMBOL schottky -448 -496 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky -448 -368 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D2
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
TEXT -320 -56 Left 2 ;GH SPAD Quench Aug 2018
TEXT -256 -192 Left 2 !K1 L1 L2 L3 L4 L5 L6 0.99
TEXT -488 -56 Left 2 ;SPAD
TEXT -368 -704 Left 2 ;VERSA-PAC 6x3uH
TEXT -136 -704 Left 2 ;LOT OF INTER WINDING STRAY CAP (C3-C12)
TEXT -824 -720 Left 2 ;ANTI BURNOUT R
TEXT 288 -352 Left 2 !.tran 500n
TEXT 280 -160 Left 2 ;Paralled 74ABT541 line driver
TEXT 288 -128 Left 2 ;or FET gate driver or similar
TEXT 152 -672 Left 2 ;GUESSED AT 10pF
Reply by George Herold●August 20, 20182018-08-20
On Monday, August 20, 2018 at 4:13:28 PM UTC-4, piglet wrote:
> On 19/08/2018 20:20, George Herold wrote:
> > On Sunday, August 19, 2018 at 9:07:04 AM UTC-4, piglet wrote:
> >> On 19/08/2018 03:10, George Herold wrote:
> >>> On Saturday, August 18, 2018 at 2:40:03 PM UTC-4, piglet wrote:
> >>>> On 17/08/2018 17:09, George Herold wrote:
> >>>>> Hi All, well one last swing at my HV reset spad circuit. (circuit
> >>>>> scribble or spice file on request.) I need a low input C, P-fet with
> >>>>> decent Vds (~40V or greater.)* (It needs to turn off fast (<50ns),
> >>>>> some pfets look to have built in gate resistors for safety and these
> >>>>> are slower.)
> >>>>>
> >>>>> Anyway at the moment I've got the BSS84 from infineon
> >>>>> https://www.infineon.com/dgdl/Infineon-BSS84PW-DS-v01_05-en.pdf?fileId=db3a3043321e49940132482056d32474
> >>>>>
> >>>>> And the Si1021 from Vishay
> >>>>> http://www.vishay.com/docs/71410/71410.pdf
> >>>>>
> >>>>> Do you have another suggestion that I should put on my shopping list?
> >>>>>
> >>>>> Say, everyone seems to make a BSS84 with slightly different specs...
> >>>>> what's up with that?
> >>>>>
> >>>>> Oh at the moment this is running with a VP0106. (60 pF Cin)
> >>>>> This is with dummy load, (3.3 pF cap)
> >>>>> Chan. 1 is gate voltage,
> >>>>> Chan. 2 is HV on top of cap, about 20V reset (not to scale)
> >>>>>
> >>>>> https://www.dropbox.com/s/cmfsjbgiyo3b255/pfet-rst.BMP?dl=0
> >>>>>
> >>>>> George H.
> >>>>>
> >>>>>
> >>>>> *If there was a much better N-FET, I could flip the whole thing over and run
> >>>>> it from a negative HV supply.
> >>>>>
> >>>>
> >>>> If I read the scope right looks like the gate drive slews to -4V in
> >>>> 20ns, which if your 60pF Cin is used then grossly simplified I make the
> >>>> gate drive current a mere 12mA.
> >>> I think less (Dang I should have put my spice sim in drop box.)
> >>> I'm a brute force type. (subtle takes experience)
> >>> The p-fet's source is.. (there are some 1nF and 10nF not shown)
> >>>
> >>> HV---+---1mA limit---+--------+
> >>> | | |
> >>> 0.1mA lim. | R4 500
> >>> | | S |
> >>> +-----------------+| +---+
> >>> | | | | |
> >>> R1 400k 1M? R2 | | |
> >>> | | +| |
> >>> +--+--|<--|<--|<---+ + D |
> >>> | | | |
> >>> R5 C 3.3pF 2M? R3 \ |
> >>> 4M | | \|
> >>> +--+-Gnd Gnd |--4V
> >>> /|
> >>> sig gen.-74hc14 x6 ---R6 100--< |
> >>>
> >>> The diodes are 1n5711 Schottky.
> >>> (I don't need three anymore.)
> >>> The C is my spad and R5 leaks off some voltage.
> >>>
> >>> I get about 25 mA through R6, which give me ~10 Vgs if
> >>> I pulse it for a long time. (1-200ns)
> >>>
> >>> My big time suck is R4 and Cin..
> >>> Say if I stuck the right amount of L in series with
> >>> R4, would that get the gate on sooner and off faster?
> >>>
> >>> George H.
> >>>
> >>>
> >>>
> >>>
> >>>>
> >>>> Also looks like the drain doesnt do much till gate hits 3.5V so if you
> >>>> can increase the gate drive voltage, sharpen it and make it stiffer then
> >>>> you'd get closer to your target?
> >>>>
> >>>> piglet
> >>>
> >>
> >> Not sure I understand the circuit, do you have the P-fet normally ON and
> >> want to switch it off rapidly or do you have the fet normally OFF and
> >> want to switch it on rapidly. What is the desired action?
> > Normally off.. it is getting a bit byzantine.
> > I'm sorta blowing ~30mA on the gate to switch 3 mA across R1.
> >
> >>
> >> Does that 1mA limit fight your gate drive or are there bypass caps
> >> capable of supporting brief current draws?
> > Yeah bypass caps not shown, 1nF on backside of 0.1mA limit and
> > 10nF behind 1mA .
> >>
> >> Looks like source and gate resistor R4 return to different points which
> >> could exceed Vgs?
> > I hadn't thought about the separate limits turning on at different times
> > and blowing the pfet, so I owe you another beer, or beverage of your choice.
> >
> > George H.
> >
> >>
> >> piglet
> >
>
> What do want the pfet turning on to do to your SPAD? Looks like it
> doesn't do anything to reduce the spad bias if I read the ascii art
> correctly - are those diodes right?
>
> piglet
Right, when the spad fires, all it's over voltage charge goes away.
(~10-20 V over-voltage) It then takes a long time to recharge through
the 400k R. (this large value 'self-quenches' the avalanche)
The pfet is to speed up the recharge time...
you posted some nice circuits that both quenched and recharged,
I may have to do that.. But this keeps the quench and reset separate.
I don't understand how the self-quench works, so I figured it might be nice
to keep it separate.
Yeah diodes are right, they are meant to shield the spad C from the switch
C. I figure I'll put another sting on the other side,
same voltage drop.
George H.
Reply by piglet●August 20, 20182018-08-20
On 19/08/2018 20:20, George Herold wrote:
> On Sunday, August 19, 2018 at 9:07:04 AM UTC-4, piglet wrote:
>> On 19/08/2018 03:10, George Herold wrote:
>>> On Saturday, August 18, 2018 at 2:40:03 PM UTC-4, piglet wrote:
>>>> On 17/08/2018 17:09, George Herold wrote:
>>>>> Hi All, well one last swing at my HV reset spad circuit. (circuit
>>>>> scribble or spice file on request.) I need a low input C, P-fet with
>>>>> decent Vds (~40V or greater.)* (It needs to turn off fast (<50ns),
>>>>> some pfets look to have built in gate resistors for safety and these
>>>>> are slower.)
>>>>>
>>>>> Anyway at the moment I've got the BSS84 from infineon
>>>>> https://www.infineon.com/dgdl/Infineon-BSS84PW-DS-v01_05-en.pdf?fileId=db3a3043321e49940132482056d32474
>>>>>
>>>>> And the Si1021 from Vishay
>>>>> http://www.vishay.com/docs/71410/71410.pdf
>>>>>
>>>>> Do you have another suggestion that I should put on my shopping list?
>>>>>
>>>>> Say, everyone seems to make a BSS84 with slightly different specs...
>>>>> what's up with that?
>>>>>
>>>>> Oh at the moment this is running with a VP0106. (60 pF Cin)
>>>>> This is with dummy load, (3.3 pF cap)
>>>>> Chan. 1 is gate voltage,
>>>>> Chan. 2 is HV on top of cap, about 20V reset (not to scale)
>>>>>
>>>>> https://www.dropbox.com/s/cmfsjbgiyo3b255/pfet-rst.BMP?dl=0
>>>>>
>>>>> George H.
>>>>>
>>>>>
>>>>> *If there was a much better N-FET, I could flip the whole thing over and run
>>>>> it from a negative HV supply.
>>>>>
>>>>
>>>> If I read the scope right looks like the gate drive slews to -4V in
>>>> 20ns, which if your 60pF Cin is used then grossly simplified I make the
>>>> gate drive current a mere 12mA.
>>> I think less (Dang I should have put my spice sim in drop box.)
>>> I'm a brute force type. (subtle takes experience)
>>> The p-fet's source is.. (there are some 1nF and 10nF not shown)
>>>
>>> HV---+---1mA limit---+--------+
>>> | | |
>>> 0.1mA lim. | R4 500
>>> | | S |
>>> +-----------------+| +---+
>>> | | | | |
>>> R1 400k 1M? R2 | | |
>>> | | +| |
>>> +--+--|<--|<--|<---+ + D |
>>> | | | |
>>> R5 C 3.3pF 2M? R3 \ |
>>> 4M | | \|
>>> +--+-Gnd Gnd |--4V
>>> /|
>>> sig gen.-74hc14 x6 ---R6 100--< |
>>>
>>> The diodes are 1n5711 Schottky.
>>> (I don't need three anymore.)
>>> The C is my spad and R5 leaks off some voltage.
>>>
>>> I get about 25 mA through R6, which give me ~10 Vgs if
>>> I pulse it for a long time. (1-200ns)
>>>
>>> My big time suck is R4 and Cin..
>>> Say if I stuck the right amount of L in series with
>>> R4, would that get the gate on sooner and off faster?
>>>
>>> George H.
>>>
>>>
>>>
>>>
>>>>
>>>> Also looks like the drain doesnt do much till gate hits 3.5V so if you
>>>> can increase the gate drive voltage, sharpen it and make it stiffer then
>>>> you'd get closer to your target?
>>>>
>>>> piglet
>>>
>>
>> Not sure I understand the circuit, do you have the P-fet normally ON and
>> want to switch it off rapidly or do you have the fet normally OFF and
>> want to switch it on rapidly. What is the desired action?
> Normally off.. it is getting a bit byzantine.
> I'm sorta blowing ~30mA on the gate to switch 3 mA across R1.
>
>>
>> Does that 1mA limit fight your gate drive or are there bypass caps
>> capable of supporting brief current draws?
> Yeah bypass caps not shown, 1nF on backside of 0.1mA limit and
> 10nF behind 1mA .
>>
>> Looks like source and gate resistor R4 return to different points which
>> could exceed Vgs?
> I hadn't thought about the separate limits turning on at different times
> and blowing the pfet, so I owe you another beer, or beverage of your choice.
>
> George H.
>
>>
>> piglet
>
What do want the pfet turning on to do to your SPAD? Looks like it
doesn't do anything to reduce the spad bias if I read the ascii art
correctly - are those diodes right?
piglet
Reply by George Herold●August 19, 20182018-08-19
On Sunday, August 19, 2018 at 1:12:14 AM UTC-4, Tim Williams wrote:
> "George Herold" <gherold@teachspin.com> wrote in message
> news:9f4aa6e9-2edd-48e0-8045-c41b31e13c9c@googlegroups.com...
> >> https://www.digikey.com/product-detail/en/epc/EPC2038/917-1138-1-ND/5774048
> >>
> > Oh boy those look like fun... 450 bump spacing.. I assume that's
> > um. Is it possible to dead bug hand solder such a tid bit?
>
> How much Valium do you have on hand? :^)
A physics colleague would do four wire gold leads to samples
with little dabs of silver paint.
He claimed to need exactly 1/2 a beer, to relax just a bit.
George H.
>
> Could do what JL did, spin a bunch of interposer boards. Fan it out to an
> SO-8 footprint, for example. Given suitable consideration for parasitics of
> course -- GaN screams, compared to Si.
>
> Tim
>
> --
> Seven Transistor Labs, LLC
> Electrical Engineering Consultation and Design
> Website: https://www.seventransistorlabs.com/
Reply by George Herold●August 19, 20182018-08-19
On Sunday, August 19, 2018 at 9:07:04 AM UTC-4, piglet wrote:
> On 19/08/2018 03:10, George Herold wrote:
> > On Saturday, August 18, 2018 at 2:40:03 PM UTC-4, piglet wrote:
> >> On 17/08/2018 17:09, George Herold wrote:
> >>> Hi All, well one last swing at my HV reset spad circuit. (circuit
> >>> scribble or spice file on request.) I need a low input C, P-fet with
> >>> decent Vds (~40V or greater.)* (It needs to turn off fast (<50ns),
> >>> some pfets look to have built in gate resistors for safety and these
> >>> are slower.)
> >>>
> >>> Anyway at the moment I've got the BSS84 from infineon
> >>> https://www.infineon.com/dgdl/Infineon-BSS84PW-DS-v01_05-en.pdf?fileId=db3a3043321e49940132482056d32474
> >>>
> >>> And the Si1021 from Vishay
> >>> http://www.vishay.com/docs/71410/71410.pdf
> >>>
> >>> Do you have another suggestion that I should put on my shopping list?
> >>>
> >>> Say, everyone seems to make a BSS84 with slightly different specs...
> >>> what's up with that?
> >>>
> >>> Oh at the moment this is running with a VP0106. (60 pF Cin)
> >>> This is with dummy load, (3.3 pF cap)
> >>> Chan. 1 is gate voltage,
> >>> Chan. 2 is HV on top of cap, about 20V reset (not to scale)
> >>>
> >>> https://www.dropbox.com/s/cmfsjbgiyo3b255/pfet-rst.BMP?dl=0
> >>>
> >>> George H.
> >>>
> >>>
> >>> *If there was a much better N-FET, I could flip the whole thing over and run
> >>> it from a negative HV supply.
> >>>
> >>
> >> If I read the scope right looks like the gate drive slews to -4V in
> >> 20ns, which if your 60pF Cin is used then grossly simplified I make the
> >> gate drive current a mere 12mA.
> > I think less (Dang I should have put my spice sim in drop box.)
> > I'm a brute force type. (subtle takes experience)
> > The p-fet's source is.. (there are some 1nF and 10nF not shown)
> >
> > HV---+---1mA limit---+--------+
> > | | |
> > 0.1mA lim. | R4 500
> > | | S |
> > +-----------------+| +---+
> > | | | | |
> > R1 400k 1M? R2 | | |
> > | | +| |
> > +--+--|<--|<--|<---+ + D |
> > | | | |
> > R5 C 3.3pF 2M? R3 \ |
> > 4M | | \|
> > +--+-Gnd Gnd |--4V
> > /|
> > sig gen.-74hc14 x6 ---R6 100--< |
> >
> > The diodes are 1n5711 Schottky.
> > (I don't need three anymore.)
> > The C is my spad and R5 leaks off some voltage.
> >
> > I get about 25 mA through R6, which give me ~10 Vgs if
> > I pulse it for a long time. (1-200ns)
> >
> > My big time suck is R4 and Cin..
> > Say if I stuck the right amount of L in series with
> > R4, would that get the gate on sooner and off faster?
> >
> > George H.
> >
> >
> >
> >
> >>
> >> Also looks like the drain doesnt do much till gate hits 3.5V so if you
> >> can increase the gate drive voltage, sharpen it and make it stiffer then
> >> you'd get closer to your target?
> >>
> >> piglet
> >
>
> Not sure I understand the circuit, do you have the P-fet normally ON and
> want to switch it off rapidly or do you have the fet normally OFF and
> want to switch it on rapidly. What is the desired action?
Normally off.. it is getting a bit byzantine.
I'm sorta blowing ~30mA on the gate to switch 3 mA across R1.
>
> Does that 1mA limit fight your gate drive or are there bypass caps
> capable of supporting brief current draws?
Yeah bypass caps not shown, 1nF on backside of 0.1mA limit and
10nF behind 1mA .
>
> Looks like source and gate resistor R4 return to different points which
> could exceed Vgs?
I hadn't thought about the separate limits turning on at different times
and blowing the pfet, so I owe you another beer, or beverage of your choice.
George H.
>
> piglet
Reply by Piglet●August 19, 20182018-08-19
On 19/08/2018 03:10, George Herold wrote:
> On Saturday, August 18, 2018 at 2:40:03 PM UTC-4, piglet wrote:
>> On 17/08/2018 17:09, George Herold wrote:
>>> Hi All, well one last swing at my HV reset spad circuit. (circuit
>>> scribble or spice file on request.) I need a low input C, P-fet with
>>> decent Vds (~40V or greater.)* (It needs to turn off fast (<50ns),
>>> some pfets look to have built in gate resistors for safety and these
>>> are slower.)
>>>
>>> Anyway at the moment I've got the BSS84 from infineon
>>> https://www.infineon.com/dgdl/Infineon-BSS84PW-DS-v01_05-en.pdf?fileId=db3a3043321e49940132482056d32474
>>>
>>> And the Si1021 from Vishay
>>> http://www.vishay.com/docs/71410/71410.pdf
>>>
>>> Do you have another suggestion that I should put on my shopping list?
>>>
>>> Say, everyone seems to make a BSS84 with slightly different specs...
>>> what's up with that?
>>>
>>> Oh at the moment this is running with a VP0106. (60 pF Cin)
>>> This is with dummy load, (3.3 pF cap)
>>> Chan. 1 is gate voltage,
>>> Chan. 2 is HV on top of cap, about 20V reset (not to scale)
>>>
>>> https://www.dropbox.com/s/cmfsjbgiyo3b255/pfet-rst.BMP?dl=0
>>>
>>> George H.
>>>
>>>
>>> *If there was a much better N-FET, I could flip the whole thing over and run
>>> it from a negative HV supply.
>>>
>>
>> If I read the scope right looks like the gate drive slews to -4V in
>> 20ns, which if your 60pF Cin is used then grossly simplified I make the
>> gate drive current a mere 12mA.
> I think less (Dang I should have put my spice sim in drop box.)
> I'm a brute force type. (subtle takes experience)
> The p-fet's source is.. (there are some 1nF and 10nF not shown)
>
> HV---+---1mA limit---+--------+
> | | |
> 0.1mA lim. | R4 500
> | | S |
> +-----------------+| +---+
> | | | | |
> R1 400k 1M? R2 | | |
> | | +| |
> +--+--|<--|<--|<---+ + D |
> | | | |
> R5 C 3.3pF 2M? R3 \ |
> 4M | | \|
> +--+-Gnd Gnd |--4V
> /|
> sig gen.-74hc14 x6 ---R6 100--< |
>
> The diodes are 1n5711 Schottky.
> (I don't need three anymore.)
> The C is my spad and R5 leaks off some voltage.
>
> I get about 25 mA through R6, which give me ~10 Vgs if
> I pulse it for a long time. (1-200ns)
>
> My big time suck is R4 and Cin..
> Say if I stuck the right amount of L in series with
> R4, would that get the gate on sooner and off faster?
>
> George H.
>
>
>
>
>>
>> Also looks like the drain doesnt do much till gate hits 3.5V so if you
>> can increase the gate drive voltage, sharpen it and make it stiffer then
>> you'd get closer to your target?
>>
>> piglet
>
Not sure I understand the circuit, do you have the P-fet normally ON and
want to switch it off rapidly or do you have the fet normally OFF and
want to switch it on rapidly. What is the desired action?
Does that 1mA limit fight your gate drive or are there bypass caps
capable of supporting brief current draws?
Looks like source and gate resistor R4 return to different points which
could exceed Vgs?
piglet