Puzzle 60 of 100

Two phases

Goal

Make Y high while CLK is low and Z high while CLK is high, with a short gap at each change so that they are never high together.

Die: 46 by 16 squares
Layers: Metal, Polysilicon, Contact, N active, P active, N well
Input: CLK
Outputs: Y, Z
Supply: VDD
Ground: GND

Go to the solution

New in this puzzle

Two phases

Circuits that pass data from one stage to the next often need two clock phases that are never high together. Gating a clock with a delayed copy of itself leaves a gap at each edge as long as the delay.

Hint

Each chain gives a late copy of CLK. Y is the NOR of CLK and its copy, so it rises only after the copy falls; Z is the AND of the two, from a NAND gate and an inverter, so it rises only after the copy rises.

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 60, Two phases, 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 60, Two phases, 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 60, Two phases, 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

Metal252 squares
Polysilicon107 squares
Contact54 squares
N active25 squares
P active50 squares
N well176 squares
Input padCLK
Output padY, Z
Supply padVDD
Ground padGND
Squares you draw, change, or erase169 squares

About the drawing

The drawing uses 440 of the die's 736 squares.
Part of the drawing is in place when the puzzle opens. To finish it, paint 165 empty squares and change 4 drawn squares.
It forms 18 transistors: 9 N transistors and 9 P transistors. Each one is a place where polysilicon crosses active silicon.
54 contacts join metal to the polysilicon or active silicon under it.

Starting drawing for puzzle 60, Two phases, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.