Gary Pimm's CCS

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cv
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#1 Gary Pimm's CCS

Post by cv »

New thread where this belongs...

While you're here Gary, I'm considering using a CCS to load a single ended VFET; I'm thinking around 1A current and a max swing of 8V (if that) across the load. Any recommendations for devices / particular choice of topology from your own variations?

*Most* appreciated!

Cheers,
cv
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gpimm
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#2

Post by gpimm »

I'm thinking, slowly...

Don't have time this evening to come up with a semi intelligent answer (if ever...) but the background task has been loaded.

Gary
cv
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#3

Post by cv »

Hey Gary,
Don't worry - it was more if you had some recommendations already.
Salas at diyaudio has some interesting schemes and I've seen the IRFBC20 recommended elsewhere.

I will (when I get time) try and model some up accurately and compare to your designs in LTSpice, that should give a decent indication.

Best,
cv
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gpimm
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#4

Post by gpimm »

Hi cv,

If you wanted info about high voltage CCS's I've got lots of input and ideas but when it comes to low voltage high current for audio use I don't have any experience (yet).

All the development I've done so far has been centered on reducing the shunt capacitance of the CCS. This pretty much requires running each device with 10 to 15 volts across it minimum. When running a high current CCS with the higher voltage drops across the devices the power dissipated gets high really fast.

One thing that comes to mind is using a P-channel MOSFET. This would make the biasing easier as you would pull the gate down to turn on the device. Not much input...

Gary

Gary
cv
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#5

Post by cv »

Hey Gary,

I had a good read of your stuff online - some wonderful info there. Between the various design insights, datasheets and LTSpice, I should be good. Had much the same thoughts as you regarding the trade-off between high Vds/low capacitance and power dissipation. Fortunately, I think I can afford 14V across mosfet and a bit under 1A current, so feasible.

Came across some data on Mistubishi RF mosfets that look great but they are hard to find - at least, from trusted sources.

Anyway, thanks again for the insights and novel design ideas, most appreciated.

cheers
cv
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