Puzzle 67 of 100

Inputs from above

Goal

Make Y low only while A and B are both high. The NAND gate is drawn, and its pads sit in a row on the top edge, above the VDD rail.

Die: 7 by 14 squares
Layers: Metal, Polysilicon, Contact, N active, P active, N well, Metal 2, Via
Inputs: A, B
Output: Y
Supply: VDD
Ground: GND

Go to the solution

New in this puzzle

Down to a gate

A signal on metal 2 reaches a gate in two steps: a via down to metal, then a contact from that metal to the polysilicon. The via and the contact sit in neighboring squares.

Hint

The pads leave no room for a contact beside them, and metal under a pad would touch the rail. Put a via on each pad and come down over the rail on metal 2. Beside each gate, a via takes the signal down to metal, and a contact joins that metal to the polysilicon.

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 67, Inputs from above, 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 67, Inputs from above, 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 67, Inputs from above, 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

Metal40 squares
Polysilicon22 squares
Contact10 squares
N active5 squares
P active10 squares
N well28 squares
Metal 231 squares
Via7 squares
Input padA, B
Output padY
Supply padVDD
Ground padGND
Squares you draw, change, or erase28 squares

About the drawing

The drawing uses 76 of the die's 98 squares.
Part of the drawing is in place when the puzzle opens. To finish it, paint 6 empty squares and change 22 drawn squares.
It forms 4 transistors: 2 N transistors and 2 P transistors. Each one is a place where polysilicon crosses active silicon.
10 contacts join metal to the polysilicon or active silicon under it.
7 vias join metal 2 to the metal under it.

Starting drawing for puzzle 67, Inputs from above, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.