Hi All,

I would like Spice to display results in Watts or dBm. Is this even
possible? Spice only seems to want to graph voltages or currents --
and in the FFT portion it only seems to show dB. (I'm using LT
Spice).

Thanks for any help!

-Bill

On Thu, 23 Aug 2007 19:41:09 -0700, billcalley <billcalley@yahoo.com>
wrote:

>Hi All,
>
>I would like Spice to display results in Watts or dBm. Is this even
>possible? Spice only seems to want to graph voltages or currents --
>and in the FFT portion it only seems to show dB. (I'm using LT
>Spice).
>
>Thanks for any help!
>
>-Bill

I believe it's the Alt key for I*V power.

D from BC

On Aug 23, 7:55 pm, D from BC <myrealaddr...@comic.com> wrote:
> On Thu, 23 Aug 2007 19:41:09 -0700, billcalley <billcal...@yahoo.com>
> wrote:
>
> >Hi All,
>
> >I would like Spice to display results in Watts or dBm. Is this even
> >possible? Spice only seems to want to graph voltages or currents --
> >and in the FFT portion it only seems to show dB. (I'm using LT
> >Spice).
>
> >Thanks for any help!
>
> >-Bill
>
> I believe it's the Alt key for I*V power.
>
> D from BC


Hi D from BC,

I should have been far more specific! I meant force Spice to graph
the RF output signal in Watts or dBm; and more specifically during a
frequency domain FFT output.

Thanks,

-Bill

On Aug 23, 7:41 pm, billcalley <billcal...@yahoo.com> wrote:
> Hi All,
>
> I would like Spice to display results in Watts or dBm. Is this even
> possible? Spice only seems to want to graph voltages or currents --
> and in the FFT portion it only seems to show dB. (I'm using LT
> Spice).
>
> Thanks for any help!
>
> -Bill

Sure it's possible. Try this:
1. Run your simulation, and display the voltage across a resistor and
the current through that resistor.
2. Right click in the graphics window; select FFT; select both the
current and the voltage to display as FFT (so that the FFT will be
calculated for both).
3. In the FFT window, right click the voltage trace label at the
top. Change the expression to the voltage times the current.
4. Right-click in the left margin of the FFT graphic; change to a
linear display.

Presto, you should see watts displayed.

Cheers,
Tom

On Aug 23, 11:55 pm, Tom Bruhns <k7...@msn.com> wrote:
> On Aug 23, 7:41 pm, billcalley <billcal...@yahoo.com> wrote:
>
> > Hi All,
>
> > I would like Spice to display results in Watts or dBm. Is this even
> > possible? Spice only seems to want to graph voltages or currents --
> > and in the FFT portion it only seems to show dB. (I'm using LT
> > Spice).
>
> > Thanks for any help!
>
> > -Bill
>
> Sure it's possible. Try this:
> 1. Run your simulation, and display the voltage across a resistor and
> the current through that resistor.
> 2. Right click in the graphics window; select FFT; select both the
> current and the voltage to display as FFT (so that the FFT will be
> calculated for both).
> 3. In the FFT window, right click the voltage trace label at the
> top. Change the expression to the voltage times the current.
> 4. Right-click in the left margin of the FFT graphic; change to a
> linear display.
>
> Presto, you should see watts displayed.
>
> Cheers,
> Tom

Thanks Tom -- works like a charm!!

Best Regards,

-Bill