Small signal vs. Large signal analysis

Hello... I am new to the field of electronics engineering and have a
basic question about something that has been the source of some
confusion. I have taken an electronic devices and circuits course in
an Electronics Engineering Technology program and am familiar with
diode circuits as well as BJT and FET transistor circuits. However,
I've heard the terms "small signal analysis" and "large signal
analysis" being referred to several times, but it has never been fully
explained. Can someone please explain what these terms mean, the
difference between them, and when & why to use them in a given circuit
analysis/design. Any help would be appreciated.

Thanks,

Patrick

 

[John Popelish]

pdebella@aol.com wrote:

Hello... I am new to the field of electronics engineering and have a
basic question about something that has been the source of some
confusion. I have taken an electronic devices and circuits course in
an Electronics Engineering Technology program and am familiar with
diode circuits as well as BJT and FET transistor circuits. However,
I've heard the terms "small signal analysis" and "large signal
analysis" being referred to several times, but it has never been fully
explained. Can someone please explain what these terms mean, the
difference between them, and when & why to use them in a given circuit
analysis/design. Any help would be appreciated.

Thanks,

Patrick

Small signal analysis assumes that the signal swing is so small that
all nonlinearities of all the components can be ignored. The circuit
is analyzed as if it is made entirely of perfectly linear components
that are characterized for the operating bias point of the circuit.
This is strictly an AC analysis (amplitude and phase response with
respect to an AC reference signal). over a range of selected
frequencies.

Large signal analysis makes none of these simplifying assumptions, and
models the full nonlinear response of all the components, through
simulated elapsed time, with an arbitrary stimulating signal.
--
John Popelish

 

[Miles Harris]

On Tue, 11 Jan 2005 12:27:54 -0500, John Popelish <jpopelish@rica.net>
wrote:

Large signal analysis makes none of these simplifying assumptions, and
models the full nonlinear response of all the components, through
simulated elapsed time, with an arbitrary stimulating signal.

True. AKA in simulation: 'transient analysis'.