About measure of noise and flicker of LMH0387

Satoshi

Guru 19645 points

Other Parts Discussed in Thread: LMH0387

Question about 2-points below as a measure of noise and flicker with LMH0387.

・Customer was measure waveform, this amplitude is 400mVpp.

　They want to set 600mVpp, can Rref be changed and adjusted the amplitude?

　（Datasheet written in Rref=715Ω）

　If possible, Is there a relational expression of Rref value and the amplitude?

　When there are other way, please let me know.

・Is "Extended 3G Reach Mode" effective in improvement of noise and flicker?

　（I worry about increase jitter.）

　【Customer Information】

・Application：LED Panel

・Cable lengh：80m

・SMA Cable

・Data rate：2.97Gbps

・Resister：Default setting

・Control board：SDI Transmitter (LMH0387)　⇒　SMA cable (80m)　⇒　Relay board：SDI Receiver (LMH0387)　⇒　LED-Panel

　LMH0387 Transmitter circuit is below.

　LMH0387 Receiver circuit is below.

Best regards,

Satoshi

over 10 years ago

0 Nasser Mohammadi over 10 years ago

TI__Guru* 93670 points

Satoshi-San,

1). Earlier you mentioned SMA Cbale (80m). Is this 75 ohm or 50 ohm cable?

2). Rref = 715 Ohm because this guarantees about 800mV into 75 ohm impedance. You can change Rref value. Please attached note a graph showing Rref vs output amplitude into 75 Ohm impedance.

3). Power save mode improves 2.97 Gbps cable length but jitter may increase. In this case, the receiving side is expected to have higher jitter tolerance. LMH0387 2.97G cable reach is about 120m of B1694A 75 Ohm coax.

Regards,,nasser

0 Satoshi over 10 years ago in reply to Nasser Mohammadi

Guru 19645 points

Dear Nasser-san

Thank you for reply.
And, cable is 75 ohm.

Best regards,
Satoshi

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About measure of noise and flicker of LMH0387