EE 421L – Digital IC Design Lab – Lab 3

Layout of a 10-bit digital-to-analog converter (DAC)

Author: Darryl Derico

E-Mail: derico@unlv.nevada.edu

9/11/2019

Lab Description:

For this lab, I must make the layout of the 10-bit DAC I designed and simulated in Lab 2.

The 10k ohm resistor layout needs to be made prior to making the DAC.

Prelab:

Finished and utilized concepts from Tutorial 1 in recent assignments.

Lab:

Link: lab3.zip

Layout of 10k Resistor for DAC:

Using the above equation, I know that R must equal 10k as I have to make the resistor 10k ohms. The sheet resistance is between 820 and 855. Selecting 855 as the sheet resistance, I plugged 10k into R, 855 into rho/t and calculated for the ratio of L/W, getting 11.69:1 as a result. For the sake of ensuring the resistor doesn’t turn out too small, I doubled the length and width using 23.4 as the length, and 2 as the width. However, this yielded less than 10k ohms when I performed the extract. After asking Dr. Baker for some assistance, he said to increase the length to 24.6 (or a ratio of 12.3:1). This left me with a resistor 10.07k.

Extract of above Resistor:

Layout of DAC using R=10k:

The layout required a total of 28 10k resistors.

Zoomed in: