General > General Technical Chat
BJTs being phased out?
Benta:
@blueskull:
I'm with you all the way in your description of JFET applications. They are wonderful devices.
That doesn't change the fact that only very few are available today. Almost no major semiconductor manufacturers have them in their portfolio. And the ones that still have them are "pruning" their availability list.
Today, only specialty manufacturers such as linearsystems.com supply a comprehensive line of JFETs, like the famous 2SJ74/2SK170.
Like I said, it's a dying species.
LeoGray:
--- Quote from: blueskull on October 14, 2020, 01:48:07 am ---JFETs are extremely widely used in (lower power high voltage) power ICs due to the difficulty obtaining planar MOSFETs at higher Vds (remember, in a planar IC process, D and S are symmetric, so Vdg can also breakdown the fragile gate oxide). It's common practice to series connect a JFET with its gate tied to ground, with a low voltage MOSFET from the JFET's source and ground, to form a cascaded high voltage switch.
Also JFETs can be series connected without individual external gate driving circuitry, they just self balance, making them suitable for very high voltage switching that traditionally only IGBTs can do, but at a much higher speed.
--- End quote ---
I never know JFET could be used for high voltage. I always want to make a electroadhesion thing that uses around 10KV. But never found a good cheap solution for discharging switch.
Do you mind expending a little bit on the high voltage switching part? What's the buzz word I should search to find good articals and examples?
Thanks in advance.
EEVblog:
--- Quote from: Benta on October 13, 2020, 08:17:09 pm ---I'm much more worried about the JFET, which is a dying species.
--- End quote ---
I'm feeling a Save the JFET T-Shirt coming on...
bsfeechannel:
--- Quote from: Benta on October 14, 2020, 10:26:54 pm ---Today, only specialty manufacturers such as linearsystems.com supply a comprehensive line of JFETs, like the famous 2SJ74/2SK170.
Like I said, it's a dying species.
--- End quote ---
There's a discrete JFET inside every single electret microphone capsule. Maybe it is becoming a product for niche applications.
--- Quote from: EEVblog on October 15, 2020, 10:01:41 am ---I'm feeling a Save the JFET T-Shirt coming on...
--- End quote ---
Not a bad idea. I've already rescued a bunch of stray JFETs off the streets and now they are happily living in my loving parts bin.
coppice:
--- Quote from: bsfeechannel on October 15, 2020, 04:46:58 pm ---
--- Quote from: Benta on October 14, 2020, 10:26:54 pm ---Today, only specialty manufacturers such as linearsystems.com supply a comprehensive line of JFETs, like the famous 2SJ74/2SK170.
Like I said, it's a dying species.
--- End quote ---
There's a discrete JFET inside every single electret microphone capsule. Maybe it is becoming a product for niche applications.
--- End quote ---
True, but MEMS microphones are killing the market for electret microphones.
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