Circuits: VLSI

Puzzle 19 of 100

Repair an inverter

Goal

This inverter breaks three design rules. Correct the drawing so that the rule list is empty and Y is the inverse of A.

Die
12 by 12 squares
Layers
Metal, Polysilicon, Contact, N active, P active, N well
Input
A
Output
Y
Supply
VDD
Ground
GND

Go to the solution

New in this puzzle

The rule list

Each design rule error is marked on the die where it occurs and listed under Design Rules with an explanation. A drawing is complete only when the list is empty.

Hint

Read each entry under Design Rules and look at the marked squares. A contact may not sit on a gate, the polysilicon must pass one square beyond the N active silicon, and shapes may not meet only at a corner.

Solution

This is the game's reference drawing for the puzzle. It meets the goal and passes the design rules. Other drawings can pass as well.

Top View of the solved die for puzzle 19, Repair an inverter, with the Side View below it.
Top View of the solved die, captured from the game. Paths that carry a high level at the moment shown are lit. The Side View below cuts through the row between the dashed lines.
The game window in Isometric View with the solved die for puzzle 19, Repair an inverter, the guide, and the scope.
The whole game window in Isometric View. The scope on the right compares each output with its target band, and the message above it confirms that the drawing passes.
Solution drawing for puzzle 19, Repair an inverter, drawn on a numbered grid with every layer in its game color and pattern.
The solution on the grid. Squares are numbered from the top left corner, so you can count them. The dashed outline marks the squares you draw, change, or erase; the rest is drawn when the puzzle opens.

Legend

  • Metal46 squares
  • Polysilicon11 squares
  • Contact7 squares
  • N active5 squares
  • P active10 squares
  • N well32 squares
  • Input padA
  • Output padY
  • Supply padVDD
  • Ground padGND
  • Squares you draw, change, or erase3 squares

About the drawing

  • The drawing uses 80 of the die's 144 squares.
  • Part of the drawing is in place when the puzzle opens. To finish it, paint 1 empty square, change 1 drawn square, and erase 1 square.
  • At column 7, row 10, erase metal and the contact.
  • At column 7, row 11, paint polysilicon.
  • At column 10, row 11, erase metal.
  • It forms 2 transistors: 1 N transistor and 1 P transistor. Each one is a place where polysilicon crosses active silicon.
  • 7 contacts join metal to the polysilicon or active silicon under it.
Starting drawing for puzzle 19, Repair an inverter, on a numbered grid.
The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.