Dual-Stacked Connectorsims-2-TDR/EMI correlation of

Impedance & Emission-Radiation

Hany M Fahmy

May 13th , 2008

1

Model of the connector

2

Mechanical model was not complete, we got the real connector and added GND-patches to connect the shields, also added a load-brd as if

the connector is soldered-down to the brd.

E-field plots using Waveguide ports to compute the input-impedance @

the ports

3

Odd-mode @ brd-side: Pin-set-1

4E-field plots @ brd-side showing line-impedance of ~ 180-ohms

Odd-Mode @ brd-side: Pin-set-2

5

E-field plots @ brd-side showing line-impedance of ~ 199-ohms

Odd-Mode @ brd-side: Pin-set-3

6

E-field plots @ brd-side showing line-impedance of ~ 203-ohms

IL and RL using Discrete Ports

7

1

3

5

2

4

6

Cable-side Brd-side

Discrete Ports

8

Return Loss: S11, S22, S33,S44, S55 & S66

9

Dip from 800MHz to 850MHz: good for Return-Loss

Insertion-loss: S12,S21,S34,S43,S56,S65

10

Dip from 800MHz to 850MHz: Bad for Insertion-loss S12, S34, S56: brd-side

What happened to the Insertion-PWR 800MHz to 850MHz?

11

Dip from 812MHz to 860MHz: Radiation Power on brd-side: Reaching as high as 20% of power radiated

Radiated emission peaks @ 778MHz and 814MHz

12

NEXT & FEXT

13

NEXT and FEXT are better than -18dB except in the range of 800MHz to 850MHz up to -8.5dB

Surface Current on EMI-shield @ 1GHz

14

Amplitude of surface current showing hot-spots on the EMI-shieldEMI-shield provide surface-2-surface coupling better reference than the

edge-2-edge coupling provided by the GND-pins

Surface Current on interior @ 1GHz

15

GND-pins can not handle a lot of the return-current as it is edge-2-edge coupling worse than the EMI-shield which is surface-2-surface coupling

Surface Current Movie: use slide-show mode

16

Correlation with TDR measurement of the TOP-DVI connector

17

TDR the connector without soldering-down does show a small-knee as in the red-signal, Once the connector is soldered-down, then we see large peak of impedance ~ 180-ohms

TOP on P607 board

TOP (no board)

TOP on P348A02

Summary

• Sims correlate to TDR meas showing that the deff-impedance @ brd-side is ranging from 180-ohms to 200-ohms

• Sims drove the need for soldered-down connector as BKM for TDR measurements on the connector to capture such impedance impact (out-of-spec)

• Power Balance show that radiated emission peaks @ 778MHz and also 814Mhz close-by the actual emission problems

18