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Class-D/E FET Driver IC




 
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G4ZOW
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« on: April 11, 2019, 02:56:39 AM »

Always looking at simplification and reducing parts count I came across what I think is a PA/Mod PCB module from Nautel's current 1kW AM broadcast transmitter the model J1000: https://www.nautel.com/products/am-transmitters/j1000/

Here is slide show of the TX innards and on P.6 you can see this module. Note the four plastics are on the other side of the PCB but the single driver IC is on top of the board however I cannot make out the p/n (maybe it's proprietary) and wonder if anyone can make it out: https://slideplayer.com/slide/12745396/

Could it work anywhere above the AM broadcast band?

David G4ZOW/5B4
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VE3ELQ
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« Reply #1 on: April 11, 2019, 06:41:24 AM »

David,
The chip is a IR2110 half bridge driver that's been around for a while.  Without a schematic the topology is unknown but it is probably a half bridge configuration at about 1 MHZ and thats why they used that chip. I have successfully used them to drive 2 big FETs  in a half bridge pulse width modulator at 165 KHZ but there are now better options available such as the SI8234AB. Its spec'd for a Rt/Ft of 10/11 ns with a current source sink of 2A so may handle 2 MHZ or so but again there are much better options now available as RF FET drivers such as the NCP81074A though these are single drivers.

https://www.infineon.com/dgdl/ir2110.pdf?fileId=5546d462533600a4015355c80333167e

73s  Nigel

Edit:
After posting this I reviewed the slides and found the schematic of the half bridge modulator at slide 39.  This is where the IR2110 is used not in the RF deck.  The RF deck at slide 41 is a full H bridge with transformer drive to the FETs.
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G4ZOW
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« Reply #2 on: April 11, 2019, 11:45:15 AM »

Hi Nigel,

You read that slide show better than I.

Do you know then of any more modern single chip/fet drivers that could drive up to four plastics. aside from the cost this offers reduced parts count, pcb real estate and makes for a neater layout.

Use would be in a SIC design D PA ideally up to 40m.

David  G4ZOW/5B4
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« Reply #3 on: April 11, 2019, 03:27:55 PM »

Hi Nigel,

You read that slide show better than I.

Do you know then of any more modern single chip/fet drivers that could drive up to four plastics. aside from the cost this offers reduced parts count, pcb real estate and makes for a neater layout.

Use would be in a SIC design D PA ideally up to 40m.

David  G4ZOW/5B4

The best RF deck FET drivers I have tried by a wide margin are the NCP81074A.  With a Tr/Tf of 4 ns, matched delays, and 10A of source/sink they are both super fast and capable of driving higher gate C FETs. No problem with the 150pf SIC FETs at 7.3 mhz or the newer GaN FETs.  They are inexpensive and small so I recommend 1 driver per FET up nice and close to keep the gate lead as short as practicable. They work great.

https://www.onsemi.com/pub/Collateral/NCP81074-D.PDF

73s  Nigel
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G4ZOW
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« Reply #4 on: April 12, 2019, 12:20:26 AM »

Thanks Nigel and for the link.

I'll look at Mouser and get a few.

73

David  G4ZOW/5B4
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