Hi,
Could you or someone expand on this a bit for my education? Are you simply referring to "output impedance" as the inverse of transductance, or as a different parameter? And if a different parameter, what in the curves reflects the output impedance? If I sound confused, it is normal. Thanks.
Oops. I meant transconductance.
Mike Engelhardt, author of LTSPICE, seems to say that behavioral sources have an exploitable bug: they simulate noiselessly. See msg # 11349, 02 Aug 2006: Yahoo! Groups
That's not a bug, it would be rather non-physical. Behavioral sources can be used to model any number of processes, the underlying noise sources need to be inserted separately.
For instance and ideal current source does not have any noise so if you model a photodiode output you need to insert full shot noise. If you are substituting an ISRC for say a bipolar current source to simplify a circuit you would need to insert an appropriate noise current. I use an "F" source CCCS with appropriate resistor to make the noise current. Barrie Gilbert pointed me to some of these tricks 20yr. ago.
Oops. I meant transconductance.
It's dId/dVgs the change in drain current vs delta Vgs.
For operation in the saturation region, lambda is easy to derive graphically by looking at dVds/dId at constant Vgs (which is how I roughly calculated it).
http://www.ece.tamu.edu/~spalermo/ecen325/mosfet_2.pdf
Look in the handwritten part (very clear explanation, BTW) under "transistor operating in saturation region".
http://www.ece.tamu.edu/~spalermo/ecen325/mosfet_2.pdf
Look in the handwritten part (very clear explanation, BTW) under "transistor operating in saturation region".
λ is the part's deviation factor from the square law in other words. The more it deviates the less the 2nd harmonic will dominate.
Not quite lambda expresses in essence the same thing as Early voltage in a bipolar. Source degeneration OTOH does effect the square law Id vs Vgs.
A quick picture to clarify my point on modeling with ideal sources. The process of photons to carriers in a photodiode is random and has full shot noise. Most "photodiode equivalent circuits" are wrong because they simply have an ideal current source to represent the photo current. The model below fixes that, the tiny added current fixes the singularity at 0 and represents the true dark current which is only due to ionizing radiation and can typically be ignored.
Attachments
Don't they call lambda the channel width modulation in the modelling? Lambda again for the curves slant?
:edit channel length
Yes, but a FET's square law behavior is Id vs Vgs lambda/Early voltage is the influence of Vds on Id to the first order a linear output resistance effect.
Your avatar reminds me of my one trip around the Mediterranean, the Roman mosaics at Carthage were amazing. We were on that ship that sunk (months before of course).
Its from a cobblestone pavement in a Portuguese Uni. I found it online and I liked it.
..yep in Aveiro, my home town.
To answer the original question of this thread - Yes.
8 pieces of LSJ74 ULTRA LOW NOISE SINGLE P-CHANNEL JFET - Parts
8 pieces of LSK170 ULTRA LOW NOISE SINGLE N-CHANNEL JFET - Parts
If you want some, you will probably want buy them now. (Hint, Hint, Hint...)
8 pieces of LSJ74 ULTRA LOW NOISE SINGLE P-CHANNEL JFET - Parts
8 pieces of LSK170 ULTRA LOW NOISE SINGLE N-CHANNEL JFET - Parts
If you want some, you will probably want buy them now. (Hint, Hint, Hint...)
WOW.....To answer the original question of this thread - Yes.
8 pieces of LSJ74 ULTRA LOW NOISE SINGLE P-CHANNEL JFET - Parts
8 pieces of LSK170 ULTRA LOW NOISE SINGLE N-CHANNEL JFET - Parts
If you want some, you will probably want buy them now. (Hint, Hint, Hint...)
Matches? Everybody get together and decide on a simple and repeatable way that everybody can measure Idss at home, and get together and swap.
However, only differential pairs need the tight matches. N-P matches will be much easier.
And who gets to keep the best matches? Maybe DIY could do the matching?
Arm-wrestle? I don't know...
I do know that this community can figure it out. I've talked to lots and lots of you over the years, and I have always been impressed with the intelligence, kindness and enthusiasm for this hobby from everybody.
This is a great bunch of people. Good things will happen.
I do know that this community can figure it out. I've talked to lots and lots of you over the years, and I have always been impressed with the intelligence, kindness and enthusiasm for this hobby from everybody.
This is a great bunch of people. Good things will happen.
Looking for some Ultra Low Noise P-Channel JFETs??? LSJ74????
8 pieces of LSJ74 ULTRA LOW NOISE SINGLE P-CHANNEL JFET - Parts
Linear Integrated Systems announced today a limited release of small quantities of the currently un-released LSJ74, a single P-channel JFET, to the diyaudio hobbyists' exclusively thru the The diyAudio Store website.
The current demand for the LSJ74 within the OEM community continues to exceed LIS current wafer inventory, which is why LIS is offering only a limited release for the hobbyists only. The LSJ74 remains unreleased for OEM users.
During this limited release LIS will not be selling the LSJ74 directly from the LIS factory or thru LIS authorized distributors. Please do not contact the LIS factory or LIS authorized LIS distributors. All hobbyists sales inquiries should be directed to the The diyAudio Store for fulfillment.
We hope to have a full release by December, but that is what we said last year
Thank you for your patience, understanding and support.
Paul Norton
Linear Integrated Systems (Linear Systems)
Link the Announcement on Linear’s Youtube Page: LSJ74 P-Channel JFET Linear Integrated Systems Announcement - YouTube
8 pieces of LSJ74 ULTRA LOW NOISE SINGLE P-CHANNEL JFET - Parts
Linear Integrated Systems announced today a limited release of small quantities of the currently un-released LSJ74, a single P-channel JFET, to the diyaudio hobbyists' exclusively thru the The diyAudio Store website.
The current demand for the LSJ74 within the OEM community continues to exceed LIS current wafer inventory, which is why LIS is offering only a limited release for the hobbyists only. The LSJ74 remains unreleased for OEM users.
During this limited release LIS will not be selling the LSJ74 directly from the LIS factory or thru LIS authorized distributors. Please do not contact the LIS factory or LIS authorized LIS distributors. All hobbyists sales inquiries should be directed to the The diyAudio Store for fulfillment.
We hope to have a full release by December, but that is what we said last year
Thank you for your patience, understanding and support.
Paul Norton
Linear Integrated Systems (Linear Systems)
Link the Announcement on Linear’s Youtube Page: LSJ74 P-Channel JFET Linear Integrated Systems Announcement - YouTube
I thank you and Paul N very much.To answer the original question of this thread - Yes.
8 pieces of LSJ74 ULTRA LOW NOISE SINGLE P-CHANNEL JFET - Parts
8 pieces of LSK170 ULTRA LOW NOISE SINGLE N-CHANNEL JFET - Parts
If you want some, you will probably want buy them now. (Hint, Hint, Hint...)
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Pass Labs
- Will linear deliver on promised lsj74