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DS160PR410: How to understand DC Gain feature

Ruixin Feng
Intellectual 2405 points
Part Number: DS160PR410

Hi team,

since I’m not familiar with PCIe redriver, I was wondering if you could help to explain DC gain feature.

I understand that in PCIe redriver, CTEL will realize equalization by high-frequency boost and low-frequency attenuation. for DC gain, does it mean low frequency attenuation? If so, how low frequency it refer to? Lower than 4GHz? And why need GAIN and VOD both to set dc gain value? 

Another question is in datasheet 6.6, the parameter GAIN, what does “ low frequency CK” and “ratio at GAIN=L3 and GAIN=L2” mean? How to understand this spec? 
thanks!

  • 0
    TI__Guru* 93670 points

    Hi Ruixin,

    1). Please note figure 1 of the data sheet. This shows the redriver gain at each frequency. At lower frequency, for example 1GHz or lower, signal is not attenuated by the media - unlike higher frequency. In summary, we are mainly boosting high frequency content attenuated by the media and the low frequency content comes through since it is not attenuated.

    2).  GAIN refers to the flat VOD gain. By flat gain we mean the whole bandwidth - low and high frequency - is affected. For example -VOD Gain L0 to L2 -6dB means VOD at L2 is -6dB or half with respect to the VOD at L0.

    Regards,Nasser