Cable characteristic, pre-emphasis and post equalizer

[raymond_luo2003]

+equalizer +emphasis

Dear all

I need your help regarding on cable characteristic. Does anyone implement pre-emphasis and post equalizer in USB (or other SerDes Gigabit Ethernet or 1394B) transmitter and receiver respectively? If yes, what's the cable characteristic of short co-axial cable, say 5 meters or 10 meters? What's the simulation model for the PCB trace and cable? What's the pre-emphasis and post equalizer structure built in that SerDes transiver?

Thank in advance,
Raymond

 

[montage2000]

site:edaboard.com pre-emphasis

equalizer may used in RX and TX, depending on your application and spec. pre-emphasis is easy to realize but hard to adaptive. RX equalizer is easy to adaptive but more complex.

 

[montage2000]

you can see some paper in JSSC, they tell you how to do

Added after 1 minutes:

what kinds of equalizer,DFE or LE?

 

[krashkealoha]

Simulation models for the cable and PCB can be generated by either measurement or simulation. If you have the cable, measure the s-parameters of the cable using a VNA and save it in touchstone format such that you have a .S2P file to use in your simulations. If you don't have the cable you need to find out what type of cable you will be using because they have different characteristics, for example some cables come with equalizing properties. Some of the cable manufactures will provide s-parameter models for their cables on their websites or you can request them.

For PCB, you need to find out what type of material, such as FR4, Rodgers 6xxx, etc. If you have the PCB already you can measure s-parameters using a VNA or there are some software that will generate a spice netlist when you do a TDR of the PCB line using a oscilloscope. If you don't have the PCB, then a s-parameter or spice model can be generated using an EM simulator such as ADS, Sonnet, Q3D(Ansoft). The important properties to model are skin effect and dielectric loss of the PCB.

 

[hung_wai_ming@hotmail.com]

Dear Krashkealoha

If I have a touchstone 8-port cable model, how can I do the simulations in Hspice for transient analysis and also the S-parameters, can u give me an example?

 

[Manjunatha_hv]

Hello hung_wai_ming,

Upload your 8-port S-parameter file (*.s8p), I will send you the setup for simulation using HSPICE in AWR Analog Office ...

---manju---

 

[hung_wai_ming@hotmail.com]

This is the USB30 cable model

 

[hung_wai_ming@hotmail.com]

Dear Manju

It seems like Hspice can directly convert the S-parameter file into time-domain without independent extraction by setting FBASE and FMAX parameters in its Smodel instantiation. Am I right?