Why the hell don't they make 4-pin MOSFET's? A discreet device should have fewer parasitics, not more.
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3 years ago
discrete JFETs vs CMOS analog switch
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3 years ago
That's not a small-signal (lateral) MOSFET--it's a vertical power FET, albeit small.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
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3 years ago
Yes. But you asked where they are available, so I answered.
CH
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3 years ago
They did, BSS83, now discontinued. You might still be able to get the SST213. Also for some uses, the (4000-series CMOS chip) 4007 has MOSFETs with various terminals brought out, is widely stocked, but poorly specified for analog use.
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3 years ago
Here is a MOSFET with 4 terminals... The substrate has its own pin. BSS83 Datasheet
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3 years ago
PIN diode switch ?
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3 years ago
[...]
In a similar situation, I used reed switches in the series branch, because of their low open inter-contact capacitance. (Pickering series 103 SPST, 70fF.) For the shunt branch, I found the series inductance of a reed switch intolerable, so there I used BAR88 PIN diodes with a lot of forward current, because they don't otherwise work for such low frequencies.
Jeroen Belleman
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3 years ago
The cute little Fujitsu FTR DPDT relays are cheap and good to about 3 GHz.
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-- John Larkin Highland Technology, Inc trk The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
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3 years ago
I've used Omron GSK-2G-Y, similar to the one you have there. Do the Fujitsu relays survive being washed?
Jeroen Belleman
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3 years ago
We have learned to not water-wash them.
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We have two wash systems, one water and one "vapor degreaser" which is actually a dunk in boiling solvent followed by spray-down. They are happy with that process.
We used the Omrons once but don't any more for some reason.
-- John Larkin Highland Technology, Inc trk The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"