Puzzle 59 of 100

Growing stages

Goal

Y now drives 8 pF. Make Y swing fully at the ring's period, and keep the period between 17.5 and 20 ns.

Die: 52 by 15 squares
Layers: Metal, Polysilicon, Contact, N active, P active, N well
Input: EN
Output: Y
Supply: VDD
Ground: GND

New in this puzzle

Growing stages

A wide gate needs a strong driver, and a strong driver is itself a wide gate. A chain whose stages grow two to three times in width at each step drives a large load from a small node quickly, without loading that node.

Hint

One small inverter cannot swing the large load, and one wide inverter on the ring loads the ring and slows it. Grow the stages instead: a small inverter on the ring, then one with two fingers, then one with four fingers that drives Y.

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 59, Growing stages, 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 59, Growing stages, 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 59, Growing stages, 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

Metal291 squares
Polysilicon154 squares
Contact73 squares
N active34 squares
P active68 squares
N well184 squares
Input padEN
Output padY
Supply padVDD
Ground padGND
Squares you draw, change, or erase130 squares

About the drawing

The drawing uses 496 of the die's 780 squares.
Part of the drawing is in place when the puzzle opens. To finish it, paint 119 empty squares and change 11 drawn squares.
It forms 26 transistors: 13 N transistors and 13 P transistors. Each one is a place where polysilicon crosses active silicon.
73 contacts join metal to the polysilicon or active silicon under it.

Starting drawing for puzzle 59, Growing stages, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.