Circuits: VLSI

Puzzle 58 of 100

Tune the period

Goal

Make Y repeat with a period between 15.3 and 17.2 ns once EN is high.

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

Go to the solution

New in this puzzle

Fine tuning

A longer channel passes less current, and a larger load needs more charge, so either one slows a single stage. Changing one transistor or one load moves the period by less than a whole pair of stages.

Hint

Two more stages would overshoot the period. Slow one stage a little instead: make the channel of one transistor in the ring two squares long, or give a ring node more load, such as a wider output inverter.

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 58, Tune the period, 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 58, Tune the period, 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 58, Tune the period, 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

  • Metal145 squares
  • Polysilicon72 squares
  • Contact33 squares
  • N active15 squares
  • P active30 squares
  • N well92 squares
  • Input padEN
  • Output padY
  • Supply padVDD
  • Ground padGND
  • Squares you draw, change, or erase95 squares

About the drawing

  • The drawing uses 253 of the die's 420 squares.
  • Part of the drawing is in place when the puzzle opens. To finish it, paint 20 empty squares, change 65 drawn squares, and erase 10 squares.
  • It forms 10 transistors: 5 N transistors and 5 P transistors. Each one is a place where polysilicon crosses active silicon.
  • 33 contacts join metal to the polysilicon or active silicon under it.
Starting drawing for puzzle 58, Tune the period, on a numbered grid.
The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.