Supertex may have something like that.
On 14 May 2007 14:53:18 -0700, Simon S Aysdie <gwh
@ti.com> wrote:
>Does it exist? Would it work? Could it be extremely cheap? Does
>anyone make a "small" surface mount pmos depletion device at all?
I don't know of any.
How about common-base?
in--------r-----------+
|
|
e
pnp b----gnd
c
|
|
+---------------out
|
r
|
|
-5
It's not perfect, admittedly. But the pnp would be very cheap.
John
-----------------------------------------------Reply-----------------------------------------------
On May 14, 9:16 pm, John Larkin
<jjlar
@highNOTlandTHIStechnologyPART.com> wrote:
> On 14 May 2007 14:53:18 -0700, Simon S Aysdie <gwh
@ti.com> wrote:
> >Does it exist? Would it work? Could it be extremely cheap? Does
> >anyone make a "small" surface mount pmos depletion device at all?
> I don't know of any.
> How about common-base?
Better yet common emitter:
Modified drawing:
> Vcc-------R1----------+
> |
> |
> e
> pnp b----Signal In
> c
> |
> |
> +---------------out
> |
> R2
> |
> |
> -5
The modified works better with logic that pulls down better than up.
You don't want the resistors to be equal. They should be scaled to
make the gain to get the required output swing.
This circuit also has a nice feature that it is a near constant output
impedance.
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