How to bias a CS mosfet

I think Thompson has fallen in love with Fields. He follows him around and yes-mans him constantly.

Fields used to love me, said so here, but I spurned him. No wonder they attack my wife; they just can't compete with a beautiful woman.

I hope they spend their declining years happy and together. Old queens make lovely couples.

John

don't

Hey, we finally agree on something: you don't matter.

John

ftp://jjlarkin.lmi.net/

And it's not a camp, it's a cabin.

John

don't

--
I see you're using that sycophant Ian's 'bumchum' slur.
As chummy as you two are getting lately, you should get a room.

As for your question, he replied to you via a post of mine which
contained an earlier post of yours.

Now, your reply to him will be read by him when he reads this post.

That's how it works; got it?

I assume he wants to bias the drain of a linear mosfet amp to Vcc/2.

One way to do that is to servo the source current to a value that tracks Vcc, and pick the proper drain load resistor. That's perfectly feasible. [1]

Another way is to sense the average drain voltage and servo the gate.

The classic 3-resistor toob bias circuit sort of works, but has an error from variations in grid/gate transfer curve; you have to waste a lot of drop across the cathode/source resistor to swamp that. But it's probably good enough, and benefits from bypassing the cathode/source resistor. Ancient stuff.

John

[1] A fet circuit so biased looks, overall, like a resistor to ground. That's one way to make a programmable power resistor, which is handy for things like power supply and battery testing, or simulating RTDs, whatever.

Toob amps often bypassed the cathode resistor. The resistor had to be big to make the DC bias point stable, and that killed AC gain. Bypassing the cathode resistor made everybody happy.

John

It's easy to force the fet current to track Vcc, so drain voltage is kept at Vcc/2.

John

--
Had the OP asked for a hammer, would your "helpful nature" have handed
him a screwdriver as a "basic framework to adapt or build on"?

Passive-agressive lurking. Old hen tactics.

John

don't

Wrong, as always. He addressed me directly, using my last name.

Your name is AlwaysWrong.

John

Since this is something that you are, and do revert to being so often, what are you saying, exactly?

Inquiring minds want to know.

Awwww, did ums fall down and go boom?

Goash that certain place keeps hurtin'?

Bwuahahahahaha!

don't

I don't know, Larkin's awfully slow, or obstinate, or both. Definitely primo jerko ;-) ...Jim Thompson

[On the Road, in New York]

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

don't

Have

What a weirdo. He has killfiled me, and I'm practically the only thing he talks about. Passive-agressive lurking.

Definitely some strange, sick stuff going on. Yuk.

John

One of _many_possible_solutions_ (as I earlier said)....

It's not at all clear what the OP had in mind; and Ian the Jerkoff (and his friend in drag, John Larkin) sullied the path toward attaining further information. ...Jim Thompson

[On the Road, in New York]

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

--
Amazing!!!

You and Ian are so much alike that when I post something for him, you
reply to it.

Soul mates???

NymNoNuts-style replications ?:-) ...Jim Thompson

[On the Road, in New York]

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

I think it's about time that we put Larkin in put-up-or-shut-up status.

Any circuit he submits must be accompanied by components values, and either scope photos or simulation results to prove it works.

Otherwise ignore the ignoramus. ...Jim Thompson

[On the Road, in New York]

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Well, that sort of works, for 12.00 volt power at room temperature, and only imposes a 100% or so penalty on power consumption and only loses 2 volts of swing.

Only 12 parts, including the giant capacitor. Not bad for an amateur.

But JF will surely cluck at him for not posting an LT Spice netlist.

John