Circuits: VLSI

Puzzle 53 of 100

Arrive together

Goal

Y drives 2 pF and Z drives 8 pF. Make both the inverse of A, and make them switch at the moment the targets show.

Die
24 by 16 squares
Layers
Metal, Polysilicon, Contact, N active, P active, N well
Input
A
Outputs
Y, Z
Supply
VDD
Ground
GND

Go to the solution

New in this puzzle

Matched delays

Two outputs switch together when each driver has the same width for its load. A driver that is too narrow arrives late, and one that is too wide arrives early.

Hint

The delay of a stage grows with its load and shrinks with its width. Z carries four times the load of Y, so give its inverter four times the width: four fingers, each gate line with its own contact on the line from A.

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 53, Arrive together, 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 53, Arrive together, 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 53, Arrive together, 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

  • Metal128 squares
  • Polysilicon65 squares
  • Contact26 squares
  • N active12 squares
  • P active24 squares
  • N well76 squares
  • Input padA
  • Output padY, Z
  • Supply padVDD
  • Ground padGND
  • Squares you draw, change, or erase66 squares

About the drawing

  • The drawing uses 214 of the die's 384 squares.
  • Part of the drawing is in place when the puzzle opens. To finish it, paint 50 empty squares and change 16 drawn squares.
  • It forms 10 transistors: 5 N transistors and 5 P transistors. Each one is a place where polysilicon crosses active silicon.
  • 26 contacts join metal to the polysilicon or active silicon under it.
Starting drawing for puzzle 53, Arrive together, on a numbered grid.
The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.