Hi, I am using 8389833 clock buffer, I am confused about how to use the V_REF_AC pin of this chip. I am using the AC couple input, the input drvier is LMK61e08, The driver output clock is around 300MHz. The following picture is my chematic design.
the question is, when I use this design , sometimes the output of 8s89833 is unstable, when I change the AC couple capacitor from 0.1uF to 1nF, or 100pF, or 10pF, or to a 0 ohm resistor, it works fine. is there anything wrong about this design?
Hi Bob,
That would be that the LMK61e08 is not a CML driver so Figure 2D or 2C would not be used. The device providing the IN/nIN supports LVPECL up to 1 GHz –
LVDS up to 900 MHz
HCSL up to 400 MHz
So having other terminations will cause the 8389833 to have unstable operations.
Hi Michael, thanks for you reply. What do you mean by having other terminations? I am using Figure 2A design but I change it to ac couple, this should not be a problem
That is correct.