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LMK03000: LMK030000

Part Number: LMK03000

HI,

In the past I asked you about the BIAS pin of the LMK03000 family (Case CS0429711). In the datasheet it is written that it should be tied to VCC through a 1uF capacitor.

I tied it by mistake to GND through a 1uF capacitor and I asked you about this.

Your answer was:

"The purpose of a bias pin is to make sure a signal is offset to the proper voltage range. The LVDS driver for instance could be providing a DC bias to the LVDS receiver not requiring the receiver to internally bias this voltage. If the LVDS driver is AC biased the bias voltage would be required from the receiver side, if this is grounded the device would not operate correctly and possibly be pulling voltage lower than the Absolute Minimum voltage specification. We advise tying this connection to VCC through low leakage 1 uF capacitor as stated in section 6.1 Bias Pin"


In my design, the outputs are LVPECL so I have a termination at the receiver side.

Is it still be a problem that the BIAS is connected to GND instead of VCC ?

Yuval

  • Hi Yuval,

    We will get back after consulting the designer. 

  • Hi Yuval,

    See feedback below.

    Connecting 1uF cap between “BIAS PIN” and ground might still be ok for noise filtering. However, we do not have lab test data for such configuration

    The customer can measure/check its system level performance. If its noise/jitter performance is acceptable, then they do not need make change.

    So the short answer is, if you do not see noise performance degradation, you can tie the capacitor to GND.