# What is IR Drop?

**URL:** <https://forumautomation.com/t/what-is-ir-drop/12049>\
**Category:** Electrical\
**Tags:** electrical\
**Created:** [May 8, 2024, 6:11pm UTC](https://forumautomation.com/t/what-is-ir-drop/12049 "2024-05-08T18:11:28Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [May 8, 2024, 6:11pm UTC](https://forumautomation.com/t/what-is-ir-drop/12049/1 "2024-05-08T18:11:28Z")

</div>

## What is IR Drop?

The power supply (Vdd and Vss) in a chip is distributed equally over metal rails and straps, known as the power distribution network (PDN) or power grid.

 ![7](https://cdn.forumautomation.com/original/2X/0/00270076bddc93eed4e90f78a6a1ef2affff5a93.jpeg)

Each metal layer has a limited resistivity in the PDN.

When current flows through the PDN, a portion of the applied voltage is lowered according to **[Ohm’s law.](https://forumelectrical.com/what-is-ohms-law/)**

Change in electrical potential that occurs between the 2 ends of a conducting wire when current runs through it.

**[V=IR](https://forumelectrical.com/ohms-law-calculator/)**

## Types of IR Drop

There are two types.

1). Static IR Drop

2). Dynamic IR Drop

## 1). Static IR Drop

This occurs when no inputs transition in the circuit, resulting in a static condition.

## 2). Dynamic IR Drop

This occurs when the inputs in the circuit are constantly switching in a functioning condition.

## Effects of IR Drop

- The delay of standard cells is dependent on their power source.
- If the power supply drops, the delay increases, affecting the design’s performance.

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