There are numerous serious problems with this PCB. Even skimming the data sheets or design guides for the ESP32 or LDO would reveal them.
I’m puzzled why the post calls it “surprisingly good” when it’s so bad and missing basic requirements for different parts. I guess it’s surprising that anything at all was produced, but it’s weird that the author can’t identify the basic problems with the design.
This is similar to situations where someone uses an LLM to vibe code an app until it kind of works, but then an experienced developer takes one look at the codebase and can immediately see it was not developed with any understanding of the code.
The LLM generated four caps on the LDO output. They're all placed next to each other and away from the LDO, but that seems to have been a human choice. So I can't fault the LLM there.
That said, the AMS1117 datasheet shows a tantalum cap on the output. This is presumably because the non-negligible ESR helps stabilize the regulator, though they don't say that explicitly. The LM1117 datasheet explains this better, stating that "the ESR of the output capacitor should range between 0.3 Ω to 22 Ω". (These are very similar parts, just from different manufacturers.)
The ceramic caps chosen here are probably below that, so perhaps it would ring even with correct layout. The prompt guided towards that bad choice when it said all caps should be 0603, since almost all 0603 capacitors are ceramic. The LLM was free to choose a regulator optimized for use with ceramic output caps, but it probably chose the xx1117 because it's so common.
