Re: Curve Tracer

On Thu, 6 Feb 2025 23:11:58 +1100, Chris Jones
<lugnut808@spam.yahoo.com> wrote:

On 6/02/2025 2:45 pm, Bill Sloman wrote:

On-Semi makes two monolithic duals, the NST45010 and the NST45011
 
https://www.onsemi.com/pdf/datasheet/nst45010mw6-d.pdf
https://www.onsemi.com/download/data-sheet/pdf/nst45011mw6-d.pdf
 

>
What makes you think those are monolithic? I think they are separate
chips, but measured to have similar parameters, like the BCM846BS.
>
The thermal coupling between the chips will be poor, so they will no
longer be matched if the dissipation is not the same between them. You
could cascode a current mirror to fix that, but if you are trying to
make an exponentiator (as used in analogue synth VCOs) then you are
stuffed, because you need to operate the two transistors at different
currents, that being the whole point of the circuit.
>
You will know if they are monolithic because it will have a pin called
"substrate" or a note saying one of the pins is the substrate, and there
will be a spec pointing out that the voltage between the two devices
must be kept below some lowish value.
>

They are two similar chips, not monolithic. Thermals will be awful.