Hi all, I would like to measure the power consumption of the Vdd with #xschem. In my circuit, there aren't negative voltages. So, how to do that?

Instantaneous power is:

I(vdd_source_name) * v(vdd)

You can plot the power directly from the ngspice prompt:

plot i(vvcc) *v(vcc)

where

vvcc

is the vcc voltage source name. You can also plot instantaneous power in xschem graphs using simple RPN expressions. The example shown does also use a running average filter so you also get the average power.

This

I(vdd_source_name) * v(vdd)

will be in Watts?

yes.