Diode's junction capacitance related to frequency

[snvl0228]

I'm designing PSFB converter. so, I'm using SiC diode.

It's switching frequency is 100kHz.

If I change frequency 100kHz to 20kHz, diode's junction capacitance will decrease? or increase?

 

[FvM]

I won't expect significant frequency dependence of junction capacitance.

 

[danadakk]

I think its NOT a f(frequency) -

http://transport.ece.illinois.edu/ece340f12-lectures/ece340lecture27-junccap.pdf

Regards, Dana.

 

[snvl0228]

I won't expect significant frequency dependence of junction capacitance.

Thanks for your reply.

--- Updated Monday at 1:11 PM ---

I think its NOT a f(frequency) -

http://transport.ece.illinois.edu/ece340f12-lectures/ece340lecture27-junccap.pdf

Regards, Dana.

According to the document, junction capacitance is determined by reverse voltage and doping. I see.

Thank you.

 

[dick_freebird]

Capacitance "should" not depend on frequency
but your -measurement of it- may, as Rs is in
there and could affect "simpleminded"
current-for-applied-AC-voltage methods. A
VNA / s-param pull would give you the
component values for Cj and Rs.

 

[D.A.(Tony)Stewart]

Capacitance increases with power rating as Rs decreases. SiC material has a much lower RsC=Tau material time constant but other factors affect Tau (Figure of Merit) such as PIV which raises Rs or RdsOn in FETs or Rce in BJT's or IGBT's. There isn't a precise constant yet there is a consistent trend for diodes with these variables of semi- material, geometry and power rating or chip size.

However frequency is a parameter that does not change the capacitance structure of the insulation between conductors hence the value does not significantly change in this range.

 

[snvl0228]

Capacitance increases with power rating as Rs decreases. SiC material has a much lower RsC=Tau material time constant but other factors affect Tau (Figure of Merit) such as PIV which raises Rs or RdsOn in FETs or Rce in BJT's or IGBT's. There isn't a precise constant yet there is a consistent trend for diodes with these variables of semi- material, geometry and power rating or chip size.

However frequency is a parameter that does not change the capacitance structure of the insulation between conductors hence the value does not significantly change in this range.

Thanks. It helped me a lot.