# Passive Filters, Data Transmission and Equalization Oh My!

[Shahriar] is back with a new “The Signal Path” video. It has been a few months but it is okay because his videos are always packed full of good information. Some new equipment has been added to his lab and as an added bonus a quick tour of the equipment is included at the start, which is great if you like drooling over sweet machines.

The real focus of the video is high speed data communications, getting up into the GHz per second range. [Shahriar] covers filtering techniques from simple RC low pass filters to pretty complex microwave filters. Explaining frequency and time domain measurements of a 1.5Gbps signal through a low bandwidth channel. He also shows how equalization can be used to overcome low bandwidth limitations.

It is an hour long video jam packed with information, so you might want to set aside some time and have a pencil on hand before going in. It is well worth it though, so join us after the break.

## 17 thoughts on “Passive Filters, Data Transmission and Equalization Oh My!”

1. @ Kevin Dady,

I don’t wanna be a dousche but “GHz per second range” is incorrect… Hz is already “impulse/beat/wave/etc per second thus GHz per second here refer to half the derivate of what you’re talking about,somehow closer to the jerk (or acceleration of the frequency ) rather than the freq.

I state again: Not intended to blam you,just to inform, you can delete my comm once it’s corrected.

Thanks

1. RyGuy says:

Hey dude, its “blame” not “blam”. Pot/kettle….

2. Mike Field says:

You are correct.

GHz/sec would be the rate of change in frequency (e.g a signal generator could sweep between 1GHz and 10GHz at 1GHz per second).

1. Alex Rossie says:

While it’s true GHz/s could be the units for rate of change of Gigabit rate this is not necessarily the case. Since equal units doesn’t mean equal concepts.

For example, take Nm, which can be units of rotational force, or work done.

Also even if the units mean the same thing, 3m, 5m are not equal simply because their units are equal.

3. Taylor Alexander says:

+1 for Lets not say “GHz per second” when thats not what we’re talking about.

Correct units are really, really, really important in science. If we’re talking about science, we should get our units correct.

1. sk says:

Ow my head hz now.

2. user420 says:

Heh…

2. Wow, pretty long but really interesting.
I never thought about how GHz filters were made.
I’m looking forward to more of his videos.

3. GHz per second, Hackaday? Really? I read tech blogs to get away from the spurious “per unit of time” that the news media can’t seem to do without. I try not to quibble about typos, but using incorrect dimensions is a pet peeve- it makes it look like the writer doesn’t actually understand the subject matter. Given half your recent posts are about RF stuff I’m sure that’s not the case, but it’s still not great reporting.

4. MistaKD says:

I read the comments on this post purely to see how quickly the GHz per second would be called, the fact that every comment so far is calling it was brilliant :)

1. b1r6m4n says:

I just did the same exact thing…

2. The Geekiest Guy says:

Me too…

5. Miroslav says:

Simply put, one billion cycles per second per second or Bcpss.

6. Malikaii says:

Definitely very informative. Thanks for the share.

7. JTroll says:

I was going to troll the ‘cycles / sec / sec’ units but it looks like it was already done….