The question I need to solve is: how do the h parameters (hybrid) vary as a function of frequency?

In particular, I need to estimate the Y parameters (admitance parameters) for a 2N3904 transistor, but I only have the h parameters, as a function of the collector current, measured with a 1 kHz signal.

I need the Y parameters to model a circuit with this transistor, which operates at 10 Mhz. Is it possible to estimate the Y parameters @ 10 Mhz, from the h parameters @ 1 kHz?

I know that it is possible to convert from h parameters to Y parameters, but I don't know how the frequency variation affects it.

An alternative is to find a datasheet where the admittance parameters are specified for a range of frequencies, but I have searched without result.

  • \$\begingroup\$ Given Cob[coupling from col to base, and Ftau on how beta rolls off, and C_eb, what could you do? \$\endgroup\$ Apr 20, 2017 at 3:04
  • \$\begingroup\$ @analogsystemsrf You say calculate the admittances from the pi model? \$\endgroup\$ Apr 20, 2017 at 3:08
  • \$\begingroup\$ Certainly the two capacitors easily become part of a more detailed model. Ftau, describing beta rolloff, I've often used in napkin scribbles but not as part of formal model. \$\endgroup\$ Apr 20, 2017 at 3:10

1 Answer 1


Z, Y, H, S parameters are "measured" values at a specific bias and frequency.

You can convert H to Y but the bias and frequency is the same.

So 1Khz H can only be converted to 1Khz Y.


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