# Microstrip Crosstalk

## Microstrip Crosstalk Calculator

### Inputs

Source Rise Time
Tr
ns
Source Voltage
V
Volts
Length of Parallel Routes
L
Substrate Height
H
Trace Spacing
S
Substrate Dielectric
Er

### Outputs

Cross Talk Coeff:
Coupled Voltage:

#### Introduction

Crosstalk is unwanted coupled energy between traces. There are two types of cross talk forward and backward crosstalk. This tool calculates backward crosstalk which is usually the dominant crosstalk component.

#### Description

Backwards crosstalk creates a pulse width that is twice that of the propagation time of the pulse traveling the coupling distance. The amplitude of this crosstalk is what this tool calculates. The amplitude increases as the coupling length increases up to a point. At some point the amplitude will stay constant. The crosstalk coupling calculation requires information for the driver source as well as the PCB physical characteristics. This tool calculates the cross talk coefficient as well as the coupled voltage, both can be useful in crosstalk analysis.

#### Microstrip Transmission Line Models

Models have been created to approximate the characteristics of the forward crosstalk in microstrip transmission lines.

T_{RT} = 1.017\sqrt{\varepsilon _{r\cdot 0.475+0.67}}\cdot L\cdot 2

if

\frac{T_{RT}}{T_{R}}\leq 1

then

CT_{dB} = 20\log \left ( \frac{1}{1+\left ( \frac{S}{H} \right )^{2}}\cdot \frac{T_{RT}}{T_{R}} \right )

V_{crosstalk} = V\cdot \frac{1}{1+\left ( \frac{S}{H} \right )^{2}}\cdot \frac{T_{RT}}{T_{R}}

else

CT_{dB} = 20\log \left ( \frac{1}{1+\left ( \frac{S}{H} \right )^{2}}\right )

V_{crosstalk} = V\cdot \frac{1}{1+\left ( \frac{S}{H} \right )^{2}}