eldo_user

Working with S, Y, Z Parameters
Simulating a Block Defined by S Parameters
Simulating a Block Defined by S Parameters
The large signal S parameters model a component’s behavior in the frequency domain. Eldo
simulates the circuit using the included S-parameter data for any number of N-port blocks.
Transient Simulation of Circuits Characterized in the Frequency Domain . . . . . . . . . 691
Technical Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692
Implementation Issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 695
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 696
Basic Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Detailed Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Instantiating a Block Defined by S, Y, Z Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . 699
Touchstone Data File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705
CITIfile Data File Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708
Instantiating a Block Defined by X-Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 710
Transient Simulation of Circuits Characterized in
the Frequency Domain
Traditionally, high frequency circuits are characterized and simulated in the frequency domain.
This is because of the difficulty of handling extremely short rise times of the order of picoseconds
and the simplicity of frequency measurement.
Today with the technological advent in high frequency circuits, there is a vital need to simulate
circuits in the time domain using electrical simulators. This is needed to simulate, for example,
a linear (lossy and maybe coupled) interconnection having a non-linear termination. Such
problems may be solved in the frequency domain using harmonic balance. If we are interested
in using pulse stimuli, the circuit must be analyzed in the time domain. Another example is the
microwave simulation of passive elements, either discrete or integrated. A user defined passive
element may be simulated by extracting its scattering (S) parameters using a standard Electro-
Magnetic (EM) solver and then using this file as an input to an S-Model. This procedure enables
the user to simulate this passive element in Eldo either with or without other linear or non-linear
elements.
The main object of the S-model GenLib library is to enable the transient analysis of precharacterized
(in the frequency domain) linear high frequency circuits with any other non-linear
components. The circuit is usually characterized by its scattering parameters. S-model also
enables the simulation of circuits characterized using their admittance (Y) or impedance (Z)
parameters. The pre-characterized circuit may have any number of ports. The following
paragraph gives a brief technical presentation of matrix representation of linear circuits.
Eldo® User's Manual, 15.3 691