Who we are
ZeptoBars is a Russian based R&D company focused on microelectronics and high-tech.
We are working on our commercial, slightly unusual microelectronic product and on the weekends having fun dissolving microchips in boiling acid. We are also trying to reinvent dye lasers utilizing the most recent advances in micro- and optoelectronics.
Die size 343x343 µm. Comparing to NXP BC847B die area is 1.5 larger (0.118 vs 0.076mm²), but maximum continuous collector current is 6 times higher (600mA vs 100mA, SOT-23 in both cases). This huge increase in current per transistor area is achieved by shunting thin (=high-resistance) base layer with metal. High resistance of base layer is the limiting factor for maximum collector current in BC847B.
Die size 2050x2169 µm, half of which is occupied by transceiver and PA, 25% - on-chip memory (rough size estimations are ~300KiB), and the rest is Xtensa LX106 CPU core and other digital logic.
Chinese engineers did an outstanding job here on finally making WiFi IoT devices cost effective. Let's hope Espressif will eventually open more internal chip information for amateurs and end users.
It is still an open question how this chip got into ex-USSR/Russia - anonymous reader left no comments on that (this smells like cold war...). It is not a secret that Russia had no extensive civilian IC assortment in manufacturing, hence all military IC's must have been designed and manufactured from scratch (i.e. all R&D, prototypes and masks must be paid by government). In such conditions providing all variety of domestic ICs is economically impossible, at least without government expenses comparable to whole world's expenses on IC R&D. So "temporary", "case-by-case" permit to use imported (both legitimately and not-so-legitimately) western ICs in military equipment "until domestic products are ready" is still here after 24 years despite numerous attempts to end this practice.
Die size 2713x2141 µm, 6µm manufacturing technology, trimming laser was leaving ~8µm diameter spots.
Oh, these rounded resistors are just beautiful... Autorouters in 2014, do you see this?
Note how amount of laser trimming on R-ladder is different for different bits.
PS. Could anyone share position of western engineers on plastic-vs-ceramic package for military/space-grade IC's? It appears modern plastic packages offer more benefits (like better G-shock/vibration reliability and obviously cost) without sacrificing anything (temperature range and moisture are less of a concern now, radiation was never a concern for a package).
Apparently there are 30 initials of the people, involved in the design of this chip mentioned at the lower right corner. Although this chip was designed after Ti acquisition of Chipcon (that happened in January 2006), it is still marked as Chipcon.