Long line video driver

Hello Neil,

Here are some documents which might help you:

• "A numerical solution to an analog problem" (to use Excel to compute a cable equalizer component values): http://www.ti.com/litv/pdf/sboa124
• "Implementing a variable length CAT5 cable equalizer (using variable gain amplifiers): http://www.ti.com/litv/pdf/sboa125

Regards,

Hooman

Hi Hooman

Thank you for your helpful reply.

I am not a design engineer but an experienced technician, so, whilst I do not expect you to design this for me if you can point me in the right direction

that would be much appreciated.

The way I envisage this is a voltage feedback op amp with the eq in the feedback loop followed by a current buffer to drive the double terminated 75ohm

line - do you think that this arrangement seems sound as a building block concept?

Many thanks and best regards

Neil 

Hi Neil,

I believe the high frequency boost part of your equalization is best done with a current feedback amplifier (CFA). The reason is that a voltage feedback amplifier loop gain is more dependent on the gain control impedance (Zg or RG: Impedance from inverting input to ground) which makes it less ideal.

Coincidentally, I just did a blog on this topic (cable equalization) based on the automation technique that Xavier Ramus has outlined in his application note:
http://www.ti.com/litv/pdf/sboa124

Here is the link to the blog. Please take a look and see if the Excel sheet within it is of much use to you to simplify your design:

http://e2e.ti.com/blogs_/b/analogwire/archive/2013/05/21/cable-equalization-101-automating-your-design.aspx

Regards,

Hooman