5 ms·

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

atomlib 13y ago
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 http://i.imgur.com/vC5VkH0.jpg
ableal 13y ago
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 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_ 13y ago
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/ http://security.cs.rpi.edu/courses/hwre-spring2014/ The slides for lecture 4 (http://security.cs.rpi.edu/courses/hwre-spring2014/Lecture4_Layout.pdf 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.
- natejenkins 13y ago
  I am and this looks awesome. Thank you!
morcheeba 13y ago
Here: http://i.imgur.com/Fk5f69k.jpg http://i.imgur.com/Fk5f69k.jpg You can see the laser has cut the resistive material, increasing the resistance.

atomlib 13y ago

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 http://i.imgur.com/vC5VkH0.jpg

ableal 13y ago

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 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_ 13y ago

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/ http://security.cs.rpi.edu/courses/hwre-spring2014/ The slides for lecture 4 (http://security.cs.rpi.edu/courses/hwre-spring2014/Lecture4_Layout.pdf 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.

natejenkins 13y ago
I am and this looks awesome. Thank you!

morcheeba 13y ago

Here: http://i.imgur.com/Fk5f69k.jpg http://i.imgur.com/Fk5f69k.jpg You can see the laser has cut the resistive material, increasing the resistance.