LMH0307: Why there are pull up resistors and a capacitor used for the Outputs

Brittany Cohen

Part Number: LMH0307

I want to use this chip to only connect one coax cable output. I planed on terminated SDO0 not with a 4.7uF cap in series with a 75 ohm resistor and connect the other output to a 75ohm resistor in parallel with the 6.8 nH inductor and then in series with a 4.7uF cap. I don't understand why this chip has pullup resistors (75 ohm) for the ouptuts and a capacitor (.1uF). Can someone please explain this to me?

-Brittany

over 5 years ago

0 Nasser Mohammadi over 5 years ago

TI__Guru* 88835 points

Hi Brittany,

This cable driver is a current mode driver and needs 75-Ohm pullup. This is like an open collector output and we need 75-ohm output. 0.1uF capacitor is needed to attenuate high frequency noise on supply so this noise would not get coupled to the output signal.

You have correct understanding of the output connections. We can review your schematic once it is available.

Regards,,nasser

0 brittany cohen over 5 years ago in reply to Nasser Mohammadi

Prodigy 20 points

Thank you very much Nasser!

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LMH0307: Why there are pull up resistors and a capacitor used for the Outputs