J

#### Joel Kolstad

- Jan 1, 1970

- 0

'allowable' S-plane locations for poles and zeroes in two port networks

parameters for passive structures, specifically Y, Z, and S parameters?

These are my thoughts:

-- Whatever applies to Y probably applies as Z as well.

-- Since Z11, Z22, Y11, and Y22 can all be seen as simple input

impedances/admittances, none of them should have right half-plane (RHP)

poles OR ZEROES.

-- Z12, Z21, Y12, and Y21 probably can't have RHP poles but probably can

have RHP zeroes.

-- S parameters are a complex enough transformation that it's unclear to me

whether or not there are any particular restrictions.

The reason I ask... I generate equivalent circuit models from measurement

data using curve fitting; the results are in the form of a rational

polynomial that can be readily factored to its pole/zero formulation. It'd

be nice to have an 'eyeball' method of ensuring the resultant ECM is stable.

Pointers to network theory books discussing this would also be appreciated.

Thanks,

---Joel Kolstad