Puzzle 52 of 100

Fingers

Goal

Y drives a 10 pF load. Make Y the inverse of A, with edges at least as fast as the target.

Die: 18 by 16 squares
Layers: Metal, Polysilicon, Contact, N active, P active, N well
Input: A
Output: Y
Supply: VDD
Ground: GND

New in this puzzle

Fingers

A wide transistor can be folded into several narrow ones side by side. Each gate line is a finger, and the contacts between the fingers alternate between the supply and the output, so neighboring fingers share them and their widths add.

Guide

Draw four gate lines down from their own contacts on the line from A, and paint P active silicon across them inside an N well.
Paint N active silicon across the same gate lines, just above the GND rail.
Place contacts between the gate lines, alternating between the supply and the output, and join the outputs to Y.

Hint

The row is too short for one gate wide enough. Cross both strips with four gate lines side by side, and let the contacts between them alternate between the supply and the output. Run each gate line up under the VDD rail to its own contact on the line from A, because a long polysilicon path to the far lines would slow them.

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 52, Fingers, 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 52, Fingers, 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 52, Fingers, 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

Metal93 squares
Polysilicon52 squares
Contact19 squares
N active9 squares
P active18 squares
N well52 squares
Input padA
Output padY
Supply padVDD
Ground padGND
Squares you draw, change, or erase113 squares

About the drawing

The drawing uses 155 of the die's 288 squares.
Part of the drawing is in place when the puzzle opens. To finish it, paint 105 empty squares and change 8 drawn squares.
It forms 8 transistors: 4 N transistors and 4 P transistors. Each one is a place where polysilicon crosses active silicon.
19 contacts join metal to the polysilicon or active silicon under it.

Starting drawing for puzzle 52, Fingers, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.