Chinese F-91W homage quartz watch : weekend die-shot

Chinese F-91W quartz watch is very similar to Casio F-91W, but fortunately does not misuse Casio trademark. Chip is 4 times smaller in Chinese version, it looks simpler, purely digital.

PCB is optimized for cost to an extreme : everything that can be integrated is integrated. There is not even a decoupling capacitor which is probably ok for digital circuits with low slew rate.

Die size 1384x1245 µm.



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Signetics 74F651F - 8-bit bus transceiver : weekend die-shot

Die size 2674x2527 µm.

AD561JD - 10-bit laser-trimmed DAC : weekend die-shot

Die size 3694x2475 µm.



Datasheet has top metal photo and high-level architecture:
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RCA CA3033 - high-current (36mA) opamp : weekend die-shot

You can feel the Rubylith vibes here. Die size 1513x1418 µm.


Schematics below:
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RCA CD40163BD - CMOS Synchronous 4-Bit Counter : weekend die-shot

Die size 2757x2111 µm.

Kwazar K140UD1B - Soviet / Ukrainian opamp : weekend die-shot

Kwazar K140UD1B was the first high-volume/most popular Soviet opamp without frequency correction. This sample was manufactured by Kwazar fab (Kyiv, Ukraine) in 1970's. One can compare it to its successor K140UD2 which had much higher open-loop gain.

Die size 1225x1228 µm.

TT04 - looking inside TinyTapeout 4 (GDS included) : weekend die-shot

Through TinyTapeout project (TT04) I got to design a microchip with a bunch of oscillators, had it working in my hands and inspected under microscope. Now we'll be able to verify if manufactured chip matches GDS design files and is there any secret sauce!

Feel free to inspect source design using KLayout, SKY130 layer definitions, and finally full original GDS design. You can hide metals and DECAP cells in KLayout to make it easier to look around and compare to photos.

You can also watch video interview with decapsulation process here.

Die size 5256x3662 µm.

TT04 with metal removed, side illumination for looks:


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