LMH0344: questions about lmh0344 input RL network

user1157370

Part Number: LMH0344

Hi all
I'm using lmh0344 as 3g-sdi input equalizer.I have some questions as fllows
The inductor of the network is 6.2nH on SD344EVK,with a 0.5pF capacitor in parallel with it.while the inductor is 6.8nH,without capacitor on SD3GDAEVK.

my question is
1.What is the principle about selecting the value of the inductor?

2.The same question remains when selecting the SRF of the inductor

3.Is the capacitor necessary?when do I have to use a capacitor?

4.what is the impedance of the SDI- line?
on SD344 and SD384, does "Z75_4" means the impedance of the SDI- line is also 75ohm?
Is there any problem if this impedance is not controlled?

thanks

over 3 years ago

0 Nasser Mohammadi over 3 years ago

TI__Guru* 88775 points

Greetings,

Please note comments below:

1). SMPTE - standard body governing SDI interfaces - provides certain requirements such as return loss. Values of inductor, Resistor, and capacitor are chosen such that device can meet these requirements. Please refer to SMPTE 424 - for example, for further details.

2). Please note response above.

3). Please note response number 1. It may not be necessary but this depends on meeting SMPTE requirements.

4). Impedance is 75-ohm. If the impedance is not 75-ohm controlled, SDI interface may not pass SMPTE requirements.

Regards,, Nasser

0 user1157370 over 3 years ago in reply to Nasser Mohammadi

Prodigy 185 points

Thanks for your reply

The "Z75_4" in the figure below is also 75-ohm?

0 Nasser Mohammadi over 3 years ago in reply to user1157370

TI__Guru* 88775 points

Greetings,

Yes it is.

Regards,, Nasser

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LMH0344: questions about lmh0344 input RL network