fz2101
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Hello Everyone,
In an application note from Maxim (APPLICATION NOTE 3630 Power Supply and Ground Design for a WiFi Transceiver), it emphasizes the need to isolate the charge pump (CP) from the VCO through proper PCB layout.
My question refers to Fig. 6 of the app note which I redrew below on the left-hand side. The app note says that GND_CP and GND_VCO have multiple vias to provide a low impedance path to the ground plane, which is the second layer of the board.
However, downbonding both GND_CP and GND_VCO to the exposed paddle, which is contacted to the ground plane through multiple vias also provides a low impedance path (right figure).
I suppose the argument is that, for the figure on the right, noise current from CP can develop a noise voltage across L_via and therefore can affect the VCO, so is it true that if L_via is reduced (by using multiple vias on the paddle), then the configuration on the right can be used?
Thanks,
frank
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