Fake audiophile opamps: OPA627 (AD744?)

[leephillips]

Counterfeiting of chips is such a big problem that the US DARPA has a major program to develop tiny cryptographic chips that can be embedded inside chip packages to prove their authenticity. It's called the SHIELD program (solicitation number DARPA-BAA-14-16 if you want to ask for money).

[AJ007]

Its not just counterfeiting that is a problem, but also recycling. Real product, but used: http://spectrum.ieee.org/semiconductors/processors/the-hidde...

[malandrew]

I'm not an EE, but I imagine that a much better solution would be a universal device where you can connect a chip and run a publicly available test suite against the chip to confirm that is performs as expected.

Like @wyager, I'm extremely skeptical of a program like SHIELD.

[wyager]

> the US DARPA has a major program to develop tiny cryptographic chips that can be embedded inside chip packages

Seems legit.

http://www-rohan.sdsu.edu/faculty/vinge/hotchips/security.ht...

[logicallee]

I wouldn't have believed that wasn't a cover story 5 years ago - today?

[hammock]

Is that for counterfeiting, or security

[natejenkins]

Can someone point out where are the laser trimmed resistors in the photos, and maybe explain some more of the components?

[ableal]

The trimmed resistors are the four brown rectangles with notches (one is shown in atomlib's pic).

The silvery surfaces are aluminum - seems a single layer of metal process. Some large plates may be capacitors.

In analog circuits, MOS transistors are often fairly big, to carry larger currents, sometimes in the tens or hundreds of milliamps. There are a few such large devices, where you can see an interdigitated structure: think two hands open flat with the fingers interpenetrating but not touching. One hand is the MOS source terminal, the other is the drain terminal, the space between is the gate that controls current flow in the channel between the two first terminals.

(Layout diagram picture: http://pages.cs.wisc.edu/~butts/icons/ex2.gif - blue is metal drain and source, red is poly gate, green squares are contacts to silicon below.)

[cc_]

If you're interested in this sort of thing, there is a great class at RPI which has its lecture slides available:

http://security.cs.rpi.edu/courses/hwre-spring2014/

The slides for lecture 4 (http://security.cs.rpi.edu/courses/hwre-spring2014/Lecture4_...) shows what various types of components (such as laser-trimmed resistors) look like on a die.

[atomlib]

Here is image Mikhail Svarichevsky (author of that blog post) posted as answer to this question in comments on Habrahabr http://i.imgur.com/vC5VkH0.jpg

[morcheeba]

Here: http://i.imgur.com/Fk5f69k.jpg

You can see the laser has cut the resistive material, increasing the resistance.

[joosters]

If you can't tell the difference without dissolving the chip in acid... perhaps then there is no difference?

[thrownaway2424]

The interesting thing here is that the part has been substituted with another part that's comparable in quality and only slightly less expensive. The margins for counterfeiting this part can't have been very good.

It's pretty common to counterfeit electronic parts. I've come across counterfeit op-amps, exotic transistors, power transistors, ordinary transistors, capacitors, and even fake resistors which is amazing. It always just makes me wonder what is wrong, collectively and institutionally, with China? Making counterfeit goods of all kinds is apparently a common line of business in China. Is it just because _everything_ is made there so counterfeiting has proportionately shifted there as well?

[vonmoltke]

In addition to what has already been stated, components have additional concerns about environmental tolerance and long-term reliability. If two chips test the same on a test bench, that just means there is no difference at this point in time and under the conditions of the test bench. It says nothing about vibration susceptibility, moisture susceptibility, EMI susceptibility, ESD sensitivity, operational and non-operational temperature ranges, or a host of other factors that affect reliability and manufacturability.

[icegreentea]

Remember that these aren't made -for- audiophiles. Audiophiles might like using these, but they are used for other uses where it would matter.

[atomlib]

According to the blog post fake opamp has higher noise levels and higher offset voltage. But I would love to see it tested on audiophiles, I'm sure they can't hear the difference.

[gcommer]

From the article:

> On the other hand AD744 has higher noise (3x) and higher offset voltage (0.5mV vs 0.1mV).

[josh-wrale]

Small parts in complex systems may make drastic outcomes (e.g. Heartbleed bug). In many cases there are so many small components that perceiving such a "difference" is a non-trivial task. Thus, not being able to identify from whence the difference sprang in the context of a complete circuit does not entail a lack of any difference. tl:dr: Difference is difference: a tautology; or rather: no difference != difference

[fnordfnordfnord]

Obviously someone noticed a problem. It was confirmed by looking directly at the silicon.

[boise]

Best to only buy from TI franchised suppliers. Can't find any that go down to $16 though

http://octopart.com/opa627au-texas+instruments-420817

[GFK_of_xmaspast]

"Hey! This is lizard oil, not snake oil!"

[njharman]

til; that resistors are trimmed with lasers http://en.wikipedia.org/wiki/Laser_trimming

[Terr_]

They also may use lasers to trim and tune the mostly-crystal oscillators used in timing circuits, such as the small quartz "tuning fork" found in many digital watches.

http://en.wikipedia.org/wiki/File:Inside_QuartzCrystal-Tunin...

[Johan-bjareholt]

I have previously bought two of these chips and they sound pretty good, sad that they are fake though.

Will buy the genuine one for comparison, will see if I can hear any sound quality difference

[darksim905]

How do they get such high resolution? An electron microscope or something? Such a cool blog, I've seen it featured on HaD a few times.

[ableal]

Analog circuits are fairly big, this is taken with a regular microscope. You can see that the chip is a few millimeters square.

Besides, electron microscope pictures are monochromatic.

[BarsMonster]

This is optical microscope with 5mp digital camera. Multiple shots (from 4 to 800 for large chips) are stitched in 1 big panorama.

[rdl]

Decent optical microscope is more than adequate for photos like that; electron microscope is for gate-level.

Zac Brown and Adam Laurie are doing awesome stuff (with cheap equipment, relatively) in chip teardowns; basically the stuff Chris Tarnovsky (flylogic, now ioactive) does with $5mm stuff, they do 90% with $5-10k.