Small and large signal S parameters

dakupoto · 2019-02-09T11:36:06+00:00

Could some electronics guru here help clarify the following. Small signal S parameter amalysis is based on small signal levels and a linearized cirucuit, with a DC operating point(bias) condition. Large signal S parameter extends this scheme to high power operating conditions of non-linear devices, where the assumptions of small signal do not hold. Large signal S parameter scheme is based on harmonic balance, which involves analyzing the signals in the frequency domain. i.e., Forier transforms. Both schemes use a 2 port network, with the signal entering at the inpit("from") port and coming out at the output("to") port. With these in mind, what about oscillators ? These are one port networks, with a 2 port component (amplifier) in it. So are large and small signal S parameters applicable to oscillators ? Amplifiers are ripe for large signal S parameters. For that matter, are the S parameters quoted for older RF|micrwave transistors small or karge signal S parameters ? All hints/suggestions are welcome. Thanks in advance.

Feb 09, 2019 41 Replies

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dakupoto 7 years ago

Thanks to all for the clarifications. So, for initial oscillator start up anaysis, manufacturer supplied small signal S parameters are required, but for teady state analysis, large signal S parameters are required. Is that correct ?

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Phil Hobbs 7 years ago

Well, you can use S parameters or SPICE, but you do have to care about both large- and small-signal conditions, yes.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com

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