is equalizer required?

Ryan Miller

Part Number: LMH0341
Other Parts Discussed in Thread: LMH0384

Hi,

I understand the normal application uses an SDI equalizer (e.g. LMH0384) before the SDI deserializer (LMH0341). Is this absolutely required? I my application, there is about 1 foot of coax from the SDI output to my input. In this case, can we avoid the equalize chip???

If so, how should the 75 ohm SDI coax be attached to the LMH0341 deserializer differential input? I had expected this would be a common question, but did not find any info in the datasheets or forum posts. (Maybe I'm missing something, sorry). Can we hook up the LMH0341 to SDI coax with the same circuit as is used with the equalizer? For example, would this work?

Thank you for considering my question!

Ryan

over 5 years ago

0 Nasser Mohammadi over 5 years ago

TI__Guru* 88895 points

Hi Ryan,

1). This may work however this all depends on the insertion loss of your 1 foot cable.

2). Also, please note LMH0341 RXIN0+/- are 100-ohm inputs and you cannot treat these as 75-ohm - as you have shown in your schematic. I believe you need a 75 to 50-ohm min-loss pad. This converts from 75 to 50 ohm impedance - doing so will cause about 7dB signal attenuation. SDI+/- shown below actually connect to RXIN0/+ of LMH0341.

Regards,,nasser

0 Ryan Miller over 5 years ago in reply to Nasser Mohammadi

Prodigy 235 points

Thank you. I will give that a try.

Interface

Interface forum

is equalizer required?