# [sdiy] current conveyor?

Kyle Stephens lightburnx at yahoo.com
Mon Feb 6 22:29:25 CET 2012

```Semi-edjamacated guess: current mirror?

Iirc, you may either need to worry about beta-matching or thermal drift depending on type, if it's discrete at least.

_Kyle

--- On Mon, 2/6/12, Stewart Pye <stewpye at optusnet.com.au> wrote:

> From: Stewart Pye <stewpye at optusnet.com.au>
> Subject: Re: [sdiy] current conveyor?
> To: synth-diy at dropmix.xs4all.nl
> Date: Monday, February 6, 2012, 1:17 PM
> Hi David,
>
> This is probably too obvious to be an option, but can you
> resign the integrator part of the circuit so that the +
> input of the op amp is at ground?
> Alternatively return the ground pin of the 2164 to +5V and
> level shift the control circuitry and input signal.
>
> Regards,
> Stewart.
>
>
> On 2/7/2012 6:47 AM, David G Dixon wrote:
> > Do any gurus here know of a circuit to convey a current
> from a virtual
> > ground point to another point at any voltage?
> Essentially, I'm trying to
> > feed the current output from a 2164 (which must feed to
> virtual ground) to
> > an integrator with a voltage of -5V at its +
> input.  I want to convey the
> > 2164's current precisely to that integrator.  I
> know I can convert the
> > current to a voltage, and then send it back to the
> integrator through
> > another resistor while also summing in a current from
> -10V through the same
> > resistor.  However, notwithstanding the fact that
> this arrangement will also
> > invert my current, input offset voltages are going to
> wreak havoc with
> > precision.  I guess what I'm asking is, is there
> any way to do this without
> > first converting the current to a voltage?  The
> current needs to be able to
> > flow in both directions.  Any help most
> appreciated.
> >
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