# Capacitor Impedance ESR vs Frequency Curve

Yageo's SMT capacitor datasheet lists the ESR vs. Frequency Curve show below:

Note that impedance (Z) is listed in units (W). How can this be understood? Why is impedance seemingly not measured in Ohms, as is customary?

• Does this answer your question? What is impedance? – tuskiomi Feb 3 at 7:36
• it's a very common inter-character set typo error, you get used to seeing it. – Neil_UK Feb 3 at 7:39

W just means $$\\Omega\$$, so Ohms.

The small letter omega: $$\\omega\$$ looks a bit like a "w".

It is possible that a "W" was typed at the Y-axis of the graph but that this wasn't converted into the Greek character $$\\Omega\$$ when the pdf file was made.

• This is a very common error seen in many datasheets, most likely a general issue with fonts or other parts of the process making the PDF. It does not take long before brains start to auto-correct that. – Justme Feb 3 at 7:39
• Omega maps to W in Windows Symbol font (IIRC), so it's likely that at some point a font substitution was made and "Symbol" was replaced by an ordinary font. These day there are better ways of inserting Greek letters but old methods are often still used – Chris H Feb 3 at 16:46