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[SOLVED] Practical circuit problems

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i was using a transformer with midpoint each primary have 120uH to get Mhz of frequency
i use 14nF but the output frequency is about 52khz what should i do to get MHz frequencies
25105730_10208300047618714_1110740664_n.png
 

Hello i cant edit my last post so i will add a new post.
25114866_10208304653533859_626369280_n.png
I try to add coil parallel to the transformer in order to increase the system frequency the result is that the frequency was increased to 250 Khz but i need 1Mhz.
 

Try to divide all capacitors with a same factor of 2,3,4... which are not in parallel with the inductors.
 

The tank isn't the main part of the circuit that sets the frequency. The feedback path that determines it is between the gate and drain of other MOSFET. Ideally, you use them to set the frequency then tune the tank to match it.

I'm still of the opinion this a BJT circuit modified for MOSFETs, I suspect if you remove R2,C2,R4 and C4 it will work just as well. The capacitors slow down the rise of gate voltage which means the MOSFETs spend more time in a partially conducting state where they are least efficient in that configuration.

Brian.
 

betwixt said:
I suspect if you remove R2,C2,R4 and C4 it will work just as well.
Click to expand...
If you remove R2 and R4 from last figure there won't be biasing for the transistors. In conducting state they need Vgs.
 

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