Schematic

Schematic is a diagram of what is connected to what, drawn with symbols and wires, not with factory shapes.

Two symbols joined by a wire that meets both. A third symbol has a wire that stops short.

The schematic is the contract. A resistor between n1 and out must become a footprint and copper, or a device and metal, that extract to the same net. The schematic does not know micrometer coordinates. The layout does not know “this is an inverter” unless someone labeled it. A page of symbols might show a box marked INV, a resistor marked 10k, and wires named clk. A 32-bit bus is one thick line on that page. In the layout that bus is 32 traces and a lot of via work.

The extracted list of devices and nets is a netlist. Comparing that list to the drawing is LVS. Geometry laws are DRC. Both checks have to pass. A schematic is a different sentence from a small layout drawn in black and white. Moving a symbol does not move silicon.

Cross-probing is the daily habit: click a wire named vref and the layout should highlight the same net. If it does not, names drifted. A small analog chip may need a 12-page schematic, while a huge digital block that is mostly hierarchy may fit on a 1-page schematic. Neither page is the mask. Keep pin order on symbols matched to cell pins so LVS does not drown in aliases.

The contract, the drawing, and the copies are covered in LVS: layout versus schematic, what is a layout, and cells and instances.