EEVblog #607 - Agilent B2912A Source Measure Unit SMU Teardown

[EEVblog]

What's inside a $13K Agilent Source Measure Unit capable of 15fA and 100nV resolution?
Plus triaxial cables, and low current measurement connection.
Data Sheet: http://cp.literature.agilent.com/litweb/pdf/5990-7009EN.pdf
User Manual
Connection Guide: http://cp.literature.agilent.com/litweb/pdf/B2900-90090.pdf
Component Datasheets:
Dual MOSFET http://www.fairchildsemi.com/ds/FD/FDS8978.pdf
OPA1611 Audio Opamp http://www.ti.com/lit/gpn/opa1611
ISO7240A Isolators: http://www.ti.com/lit/gpn/iso7240a
ADS8202 Diff Amp: http://www.analog.com/static/imported-files/data_sheets/AD8208.pdf
ADS1675 24bit ADC: http://www.ti.com/lit/gpn/ads1675
30N06 MOSFET: https://www.fairchildsemi.com/ds/FQ/FQP30N06.pdf?

[komet]

Use it to characterize that old selenium diode you have lying around!

[qwaarjet]

I have a Keithley 2400 SMU and its probably one of the most useful tools we have in our lab. We use it to drive many of our plasma probes for characterizing the performance of the Ion drives we test  with and measuring high impedance loads. Personally if I ever find a SMU on ebay for "cheap" I'll get one for my personal lab. They are great tools more people should have them.

[Smokey]

"Shhhmmmuuuu" ??  I think you're making that up

[Wytnucls]

There is an RF version, called SMURF 

[juani_c]

Is it me or one of the leads from the 10 meg (big green flat) resistors is not soldered? at min 25:53

[zimzom]

Great video,  looking forward to the practical applications follow on. If it were possible would be really interesting to see an old school model for comparison.

[robrenz]

Great teardown Dave   It would be interesting to see a zener curve done on the screen or just a leakage test like I did on the 2450 here to compare the interfaces between the Agilent and the Keithley.

[EEVblog]

Great teardown Dave   It would be interesting to see a zener curve done on the screen or just a leakage test like I did on the 2450 here to compare the interfaces between the Agilent and the Keithley.

I don't know about the keithley, but I can say the UI on the Agilent kinda sucks 

[skipjackrc4]

I definitely hope to see a video of it in use.  I've always wanted an SMU.

[SArepairman]

I think this might be the machine that I am most jealous of you for having. 

[TiN]

UI tool from website for Kei2400 is sucks too, but who cares, SMU gear is on that level already when custom software/LabView app pays for itself.

SMU is a great addition for lab, expensive but handy for lot of applications. In worst case you can you it as 4-quadrant power supply 

[c4757p]

Wow, talk about NSFW. That's one hell of an instrument. 10fA! Is there a little dude in there somewhere counting the electrons as they pass by? I couldn't see him...

10fA is one single electron per 16µs, if anyone didn't realize that.

[Psi]

Is that CR2032 leaking at 54:40 ?

[Whales]

10fA is one single electron per 16µs, if anyone didn't realize that.

*shouts*:  Companies, keep throwing expensive equipment at Dave!  We need more than Agilent to hop on board

[Whales]

Is that CR2032 leaking at 54:40 ?

I don't think so -- looks more like a surface finish + reflections.  I know lithium primaries have a lot of energy, but the CR chemistry AFAIK is current-limited and mostly indestructible.

[FrankBuss]

Interesting review. The 24 bit 4 MS/s ADC is not that expensive as I expected, Digikey sells it for $38.79. I wonder if you could just connect some long wire to it and then demodulate longwave AM radio broadcast signals, all digitally, without external filtering.

PS: Is it still Agilent or Keysight? Strange that if you click on the products link on the keysight.com homepage, it just links to agilent.com, with the same old Agilent Technologies logo. Looks like they are not really serious about the name change.

[lewis]

Wohoo! Vias under D2PAKs - I've been doing that for years and everyone keeps telling me it's like totally WAY bad. Now I feel vindicated! 

Awesome bit of kit that...

[felixd]

What about measuring uCurrent?

[Kompost]

Wohoo! Vias under D2PAKs - I've been doing that for years and everyone keeps telling me it's like totally WAY bad. Now I feel vindicated! 

Is there a reason why is it supposed to be a bad idea?

[lewis]

Wohoo! Vias under D2PAKs - I've been doing that for years and everyone keeps telling me it's like totally WAY bad. Now I feel vindicated! 

Is there a reason why is it supposed to be a bad idea?

As Dave said, mainly solder leeching through the vias taking the paste away from the top layer pad where it's supposed to be. I've never experienced a problem with this though even with via holes of up to 0.6mm diameter. I usually place thermal vias in four quadrants under the pad, leaving a cross shape of bare pad under the component. But vias directly under smaller pads (<1206) are indeed a bad idea, they do leech away noticeable amounts of solder.

Some people say that tenting the via with soldermask on the other side of the board is a good idea to help prevent the solder leeching, but I believe this is a terrible idea - the tenting traps air in the via which expands and explodes when the component is reflowed leading to voids in the solder joint between the component and pad. I now leave the underside vias untented but with minimal pad annulus so the solder can leech through but not spread on the bottom layer too far. Top-side tenting or plugged vias are great, but add cost.

[Dr. Frank]

Nice video, I would like to see a further video about the unit in operation.

I also missed details about the low current source / measure circuitry, perhaps I have to follow the video for a 2nd time.

Frank

[dexters_lab]

would be a shame not to see it working given you have some test fixtures

[Jebnor]

It would be interesting to see how far your teardown has moved the calibration.  Ask Agilent if they can give you the numbers later.

[Tek_TDS220]

These videos of teardowns of extremely high-end 'analog' equipment are my favorites.  I learn a lot about best design practice.  I've never thought of the need to shield a cooling fan for EMI, but it makes sense.  Please do a video on the use of this SMU.

This Agilent is a work of art.  I love the way they designed it to be repaired, and the thermal management.  The surface residue on the boards is surprising, but I guess it is only cosmetic.  Is it flux or a residue from the silk screen?