You're a frequency domain guy, and I'm time domain. Solder it onto an SMA and TDR it, in 30 seconds, and maybe read L+R+C directly. An SMA DC block and a 10K resistor adds variable bias.
You drink nasty dark beer, too.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Afraid it would but Phil is the guru for this stuff. I think it should be tested at the desired reverse bias voltage.
-- Regards, Joerg http://www.analogconsultants.com/
I do resonances sans SMA so it only takes 25 seconds 8-)
Now I am also making them. One brew coming up Friday if clients let me will be a Belgian Tripel. Later a Subduction Cascadian Ale. You wouldn't like either.
Yesterday I had to pick up something in the valley and I took the road bike. On the way back I had a "Repentance Ale" here:
-- Regards, Joerg http://www.analogconsultants.com/
Yeah, it'll be somewhat different due to high level injection changing the mobility. (Or something like that--I'm angling for a job doing the Friday stock market report on the radio.) ;)
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
Or designing a better opinion poll method for the next election :-)
-- Regards, Joerg http://www.analogconsultants.com/
P.S.: Us RF dudes don't like no connectars, we're gitten it dun warliss thru them thar ether waves.
No kidding, I grew up with grid dip meters and stuff. All you really need is a coil that couples to the coil of the resonant circuit and gauge resonance and 3dB bandwidth. For better accuracy I built myself a frequency counter when I was around 18, during my time in the army. Still have it, a TTL monster. It's past its time but I still can't bring myself to scrap it.
-- Regards, Joerg http://www.analogconsultants.com/
You've got to solder that photodiode to something! You can't just wave a grid-dip meter at it.
Did you build a TTL clock? For a while, everybody was building clocks.
I like this kind:
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Might do that. I now have two Measurements 59s with three heads (two HF-VHF and one UHF). They're remarkably accurate for their age and for what they are: usually the frequency scale is within 2%.
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
Just the inductor. Plus a bias if you want one and that could consist of
9V batteries. I always keep the ones removed from smoke detectors because they still have 9V.The nioce thing is you don't need any controlled wiring or layout/dremeling for fast TDR.
All the others did, I was the only one building a counter. The others were making jokes because in contrast to a TTL clock the chick magnet coefficient of a counter is near zero.
Nice. Looks like Roaring 20's style. I also like analog clocks much better.
[...]-- Regards, Joerg http://www.analogconsultants.com/
Those tube-equipped grid dip meters are almost unsurpassed. Obtaining matching acorn tubes is a challenge but luckily, if push comes to shove, there is a large stash of Russian micro tubes flooding the market. They must have built them to no end. Maybe a five-year plan gone wild.
Transistor dippers aren't bad either but they have more "modern" plastic dials and stuff. Not as accurate and not as sturdy. My dipmeter is on the second dial knob and now that Heathkit is gone that has to last until I kick the bucket. Of course, I also have a Boonton 59.
The nice thing is, you don't even need to directly contact the circuit and thus there are no extra capacitances involved. Just hold the dip meter coil near the one at the PD.
-- Regards, Joerg http://www.analogconsultants.com/
If you cool the pd, the thermal part of the Johnson noise goes down, but maybe Rs goes up, which makes more noise, so don't bother.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Unfortunately I'd need to be down below 100K to fix the problem with the SFH206K. :(
Cheers
Phil Hobbs
High level injection being when the carriers are photo-excited?
George H.
We were talking about forward bias. Diodes get into HLE really easily compared with transistors, which is why they don't obey the diode equation without a fudge factor.
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
Right, forward bias compared to reverse bias and photo generated carriers. I was thinking that the photo generated ones would be created higher in the band (Assuming photon energy well above the band gap.) But maybe my problem is I don't understand what high level injection means. (Reading this...)
I'll take Sze to bed with me tonight..... (I thought the diode non-ideality was due to where the carriers were recombining... Generation/recombo effects in the depletion region.. But it looks like there is much more to it than that.)
Sorry, I seem to be particularly dense this past month.
George H.
You and me both, brother. Too many blows to the head lately. ;)
The recombination rate is proportional to the product of the hole and electron concentrations, which is where HLI comes from.
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
I was talking to some guys who make superconductive nanowire array photodetectors, with single-photon sensitivity at liquid helium temps. It is an obscure sort of gadget.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Superconducting bolometers are the bolom. ;) I designed a spectrometer with one of those in the back end some years ago. (It hung on the front of a photoemission tool that had a SCB inside.)
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
Turns out the photodiode makers have no idea how their devices behave in reverse bias except capacitance. Most of their leakage curves are ludicrously wrong, too.
Osram claims thay the SFH206K's series resistance is 2 to 6 ohms, but they measure it in forward bias. (It's actually around 50.) Luna Semi (formerly Advanced Photonix) says 380 ohms for the same size diode (7 mm**2), which is ridiculously large.
Still waiting to hear from Vishay.
This shot-noise-limited-at-20nA-in-1MHz thing is trickier than it looks.
Cheers
Phil Hobbs
Interesting, thanks. There are probably only a handful of people who care about the series resistance. Beside the noise measurement have you tired a second method to measure the resistance? (After re-reading Sze, the forward biased I-V of a diode is complicated... (much more so than a diode connected transistor!) I should measure it sometime...
I parted ways with Advanced photonix years ago. I've got some osi-optoelectronics PD's but none with 7mm^2. What sort of capacitance do you have/need?
You can see that as the area goes down one would expect the resistance to increase.
George H.
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