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Video Tutorial on Passive Filters, Data Transmission and Equalization

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Hugoneus:
I am back! After being away for a while due to work, I have uploaded another video to "The Signal Path". This video features some more advanced topics and a 1.5Gbps data link:

In this episode Shahriar explores the world of filters! Starting from a simple lumped RC filter, he briefly covers the theory before moving onto measurement techniques. The bandwidth of the filter is verified experimentally in the time domain. A more complex RLC band-stop filter is also demonstrated with a tune-able inductor which is measured using an RLC meter. Using a Rigol spectrum analyzer with built in tracking generator and an active probe, the frequency response of the filter is measured. Several other packaged filters are also demonstrated and a microwave band-pass filter is disassembled to reveal its internal construction.

Moving onto "undesired filters", a Tyco backplane board is presented and the bandwidth limitation of the backplane traces are measured. A Xilinx FPGA board equipped with a Vertex II PRO is used to generate a 1.5Gbps PRBS data stream through the Tyco board. After observing the frequency composition of the date, pre-emphasis equalization is used to compensate the backplane frequency limitations. Eye diagram measurements verify the benefit of pre-emphasis equalization to combat inter-symbol-interference (ISI).

Please visit:

http://www.TheSignalPath.com

EEVblog:
Hi Shahriar
Great work.
Is that your personal home lab or work/university lab?

Dave.

olsenn:
I actually have a couple of questions about that spectrum analyzer if you have the time to answer... I was thinking of purchasing a Rigol DSA815 1.5GHz spectrum analyzer (~$1500) but I would like to know how it differs from the one you have, apart from half the bandwidth)? Also, I keep reading that the front-end to the device can be damaged if your input signal is too large; I'm not farmiliar with the dbm scale, but what kind of RMS voltage (sine wave) and DC offset can you  have on those things? Why aren't they high input impedance like oscilloscopes?

kaz911:

--- Quote from: olsenn on February 14, 2012, 01:26:25 am ---I actually have a couple of questions about that spectrum analyzer if you have the time to answer... I was thinking of purchasing a Rigol DSA815 1.5GHz spectrum analyzer (~$1500) but I would like to know how it differs from the one you have, apart from half the bandwidth)? Also, I keep reading that the front-end to the device can be damaged if your input signal is too large; I'm not farmiliar with the dbm scale, but what kind of RMS voltage (sine wave) and DC offset can you  have on those things? Why aren't they high input impedance like oscilloscopes?

--- End quote ---

Most SA's are limited to 16-24dBm CW (Continuous Wave) on the input and and XX Volt DC. Then you use DC blockers to filter out DC - and fixed or programmable dB attenuators to lower the input dBm. Or attenuators with DC block built in.

DC Block http://www.testequity.com/products/1501/

My BK 2650 can take signals up to 20dBm (so 100mW or 2.23 Volt RMS) - and max 25V DC.

Every 3dBm double or halves the signal - so 23 dBm is 200mW and 17dBm is 50mW)

/Kasper

Hugoneus:

--- Quote from: EEVblog on February 14, 2012, 12:25:28 am ---Hi Shahriar
Great work.
Is that your personal home lab or work/university lab?

Dave.

--- End quote ---

Hi Dave! It is nice to talk to you. I hope you and your family are doing well.

Yes, this is my personal lab at home. What you see is actually in my bedroom!  :P This is one of the reasons why I keep it clean all the time.

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