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Author Topic: Input and output impedance of a push pull amplifier using MRF300AN, MRF300BN  (Read 1310 times)

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Offline kopcicleTopic starter

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Input and output impedance of a push pull amplifier using MRF300AN, MRF300BN
« on: March 23, 2020, 06:09:33 pm »


So I woke up one day to the the NXP MRF300 and started pushing pixels...
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Offline kopcicleTopic starter

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Re: Input and output impedance of a push pull amplifier using MRF300AN, MRF300BN
« Reply #1 on: March 23, 2020, 08:11:45 pm »
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« Last Edit: March 23, 2020, 08:16:05 pm by kopcicle »
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Online T3sl4co1l

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Re: Input and output impedance of a push pull amplifier using MRF300AN, MRF300BN
« Reply #2 on: March 23, 2020, 10:03:25 pm »
Hmm, no ground support in the middle?  I guess there's going to be another layer under that.

Tim
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Offline profdc9

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Re: Input and output impedance of a push pull amplifier using MRF300AN, MRF300BN
« Reply #3 on: March 23, 2020, 11:03:21 pm »
RF MOSFETs usually have the case as the source rather than the drain, and so the transistors can be connected directly to a heatsink below and the heatsink can be grounded.  Of course, any anodizing has to be removed from the heatsink to make contact.
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Online T3sl4co1l

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Re: Input and output impedance of a push pull amplifier using MRF300AN, MRF300BN
« Reply #4 on: March 24, 2020, 02:23:58 am »
Yeah, that's the case here.  I'm thinking the source pin may end up soldered to bottom side copper somehow (e.g. loose copper foil?).  Bottom side copper being clamped (preferably with help of EMI gasket) to the heatsink (non anodized, as mentioned!) would be okay as well.

Tim
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Offline kopcicleTopic starter

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Re: Input and output impedance of a push pull amplifier using MRF300AN, MRF300BN
« Reply #5 on: March 24, 2020, 05:27:58 pm »
Tim

More or less nearly correct. The MRF300 AN has a companion part with the gate and drain pins swapped. The source is the center pin as well as the tab.
This makes for easy mounting as well as layout.
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