To JT : non T analog switches?

A while ago I asked how analog switches could pump current in the following
condition:

> >Quizz: how do you pump fraction of a uA through the resistors with the
> >switch wired as below?
> >
> > 4053
> > .------------.
> > | | ___
> > | |--|___|- GND
> > ___ | o---/| 50K
> > GND -|___|--|---o--__ |
> > 50K | o--- | ___
> > | \|--|___|- GND
> > '------------' 50K
>
> Good point, it probably IS charge injection. The measured effect of
> that WOULD vary with R value, as John seems to be seeing.

That's pretty obvious in this configuration. But the real situation was

> >
> > 4053
> > .------------.
> > | |
> > | |--||- GND
> > ___ | o---/| 1u
> > GND -|___|--|---o--__ |
> > 50K | o--- |
> > | \|--||- GND
> > '------------' 1u
>

How do you pump fraction of a uA through the resistor with the switch wired
as above?

The answer is because the 4053 has 3 switches connected in a T arrangement
to obtain high off isolation, the grounding switch conducting some of the
injected charges to ground.


Now I need a SPST with low injected charges (pC order) switch with *no* T
arrangement, and ultra low leakage (few pA order) and Ron under say 50R.

I'd like to not resort to the SD200 mosfets.

The Onsemi NLAS323 or NLAS4501 seems a perfect fit (typical 0.1pA to 1pA
leakage, Ron = 10R, Qinj=0.4pC), except I don't know how they are designed.

Jim, I think you said you've designed some switches of the Onsemi series.

Do you have any info on thoses?

And there's one strange point in the data***, which is the Ron vs
temperature.


--
Thanks,
Fred.


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