Which better for decreased inductance of GND bonding wire

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chang830

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Hi,
Pls. see the attached figure. Which decribe the GND plan and bonding wire for layout. Fig.1 used two GND pad to decrease the inductance of GND bonding wire. While Fig.2 used two bonding wire bonding to one single GND pad.

Which one is better

Thanks a lot.
 

Re: Which better for decreased inductance of GND bonding wir

I prefer two pads connected to two pins repectively, if there are more pins available.
Because current will have the same direction in the two bonding wire, mutual inductance will be an issue. The actual inductance is NOT half and may approach that of single bonding wire instead.
In double-bond case, two bonding wire are too close and will have much greater mutual inductance.
The best plan is to alternate power/gnd placement if you have adequate pins.
Notice the power and gnd must be for the same power supply.
 

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    chang830

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Re: Which better for decreased inductance of GND bonding wir

less package pin is more economical
 

Fig1 or test package ( test use )
Fig2 use for real package
 

Re: Which better for decreased inductance of GND bonding wir

Both will work. I've done 12+ GHz with fig.2 with a high current type device. You can also do Figure 1 bond pads, but they all connect to the same "post". Customers usually want the smallest package possible so you may not be allowed a lot of GND pins. Furthermore, more pins increases package size which then decreases bandwidth, if die is much smaller than package size.

If you are using a package with an exposed pad, you can down bond to the exposed pad for GND. The down bond distance is much shorter than the distance to the lead which will result in lower inductance. You can get multiple GND down bonds without increasing the number of GND pins.
 

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