The document outlines the features and capabilities of the EMI Analyst™ software suite, specifically for testing and analyzing radiated emissions using LVDS signaling. It discusses various test conditions, configurations, and results regarding the impact of common mode noise and cable shielding on emissions. Instructions are provided for using the software to mitigate electromagnetic interference in projects.

1. EMI Analyst™
EMI ANALYST™ Software Suite
I n t u i t i v e  A c c u r a t e  E f f e c t i v e
Radiated emissions example
LVDS – Low Voltage Differential Signaling

2. EMI Analyst™
Radiated Emissions Test Setup
LVDS DRIVER LVDS RECEIVER

3. EMI Analyst™
LVDS Circuit and Equivalent Model
LVDS Circuit Model
Equivalent Circuit from IBIS Model and Datasheet
DO+
DO-
RI+
RI-
100Ω
50m1.05193n
0.16890p
58
50m1.05308n
0.16861p
58
DO+
DO-
RI+
RI-
100Ω
50m 1.05193n
0.16890p 240k
50m 1.64135n
0.37335p 240k

4. EMI Analyst™
0V
VDO-
VDO+
VDM = VDO+ - VDO-
tRISE tFALL
0V
80%
20%
LVDS Circuit Characteristics
• Voltage: 360 mV, differential
• Current: 6 mA
• Rise/fall time: 700/800 psec, 20%-80%
• Skew: 400 psec typ.
• Char Z: 100 
Falling edge and rising edge waveforms

5. EMI Analyst™
Radiated Emissions Comparisons
Five conditions evaluated • Three cable configurations
• Unshielded Twisted Pair
• Shielded Twisted Pair, Braid Shield
• Shielded Twisted Pair, Conductive
Fabric Tape Shield
• Two common mode noise
sources
• CM voltage induced by other
circuits
• CM voltage induced by LDVS signal
skew
# Cable Shield CM Noise Skew
1 None (TPUJ) N N
2 None (TPUJ) Y N
3 Braid (TPSJ) Y N
4 Braid (TPSJ) Y Y
5 Conductive
Fabric Tape
(TPTJ)
Y Y

6. EMI Analyst™
• Conditions
• 10 MHz data rate
• No skew
• No CM voltage
• Ideal ground conditions
LVDS Condition 1
Unshielded Cable, No Skew, No CM noise
0V
VDO-
VDO+
VDM = VDO+ - VDO-
VCM = VDO+ + VDO-
tRISE tFALL
0V
80%
20%
DO+
DO-
RI+
RI-
100Ω

7. EMI Analyst™
RE Results for Condition 1
Unshielded Cable, No Skew, No CM noise

8. EMI Analyst™
• Conditions
• 10 MHz data rate
• No skew
• 10 mV, 1 MHz CM flat spectrum
LVDS Condition 2
Unshielded Cable, No Skew, 10 mV CM Noise
DO+
DO-
RI+
RI-
100Ω
VCM
(noise)
0V
VDO-
VDO+
VDM = VDO+ - VDO-
VCM = 10 mV
tRISE tFALL
0V
80%
20%

9. EMI Analyst™
RE Results for Condition 2
Unshielded Cable, No Skew, 10 mV CM Noise

10. EMI Analyst™
• Conditions
• 10 MHz data rate
• No skew
• 10 mV, 1 MHz system CM noise
LVDS Condition 3
Braid Shielded Cable, No Skew, 10 mV CM Noise
DO+
DO-
RI+
RI-
100Ω
VCM
(noise)
0V
VDO-
VDO+
VDM = VDO+ - VDO-
VCM = 10 mV
tRISE tFALL
0V
80%
20%

11. EMI Analyst™
RE Results for Condition 3
Braid Shielded Cable, No Skew, 10 mV CM Noise

12. EMI Analyst™
LVDS Condition 4
Braid Shielded Cable, 200 ps Skew, 10 mV CM Noise
• Conditions
• 10 MHz data rate
• 0.2 nsec signal skew induces
70 mV CM pulses
• 10 mV, 1 MHz system CM noise
DO+
DO-
RI+
RI-
100Ω
VCM
(noise)
0V
VDO-
VDO+
VDM = VDO+ - VDO-
Signal VCM = VDO+ + VDO- = 70 mV
tRISE tFALL
0V
80%
20%
System VCM = 10 mV

13. EMI Analyst™
RE Results for Condition 4
Braid Shielded Cable, 200 ps Skew, 10 mV CM Noise

14. EMI Analyst™
LVDS Condition 5
Laird Tape Shielded Cable, 200 ps Skew, 10 mV CM Noise
• Conditions
• 10 MHz data rate
• Signal skew
• No CM circuit noise
• Ideal grounding
DO+
DO-
RI+
RI-
100Ω
VCM
(noise)
Z
0V
VDO-
VDO+
VDM = VDO+ - VDO-
Signal VCM = VDO+ + VDO- = 70 mV
tRISE tFALL
0V
80%
20%
System VCM = 10 mV

15. EMI Analyst™
RE Results for Condition 5
Laird Tape Shielded Cable, 200 ps Skew, 10 mV CM Noise

16. EMI Analyst™
Visit https://www.emisoftware.com
to learn how EMI Analyst™
can prevent electromagnetic
interference for your next project.