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deembed Class Reference

Deembed a 2 port circuit from a larger 2 port circuit. More...

#include <deembed.h>

Inheritance diagram for deembed::

nport device List of all members.

Public Methods

 deembed (nport &input, nport &output, nport &measured)
 Create a deembed instance. More...

int size () const
 The number of ports of the deembeded circuit. More...


Private Methods

Matrix scat_to_abcd (const sdata &sd)
 Calculate a transmission matrix from a scattering matrix and its normalization impedance. More...

void recalc ()
 Calculate the S and C matrices, assuming for the noise calculation that the device is passive at temperature device::T. More...

void recalc_S ()
 The S matrix is calculted here. More...


Private Attributes

nport* in
 The known input subcircuit. More...

nport* out
 The known output subcircuit. More...

nport* meas
 The known entire circuit. More...

Detailed Description

Deembed a 2 port circuit from a larger 2 port circuit.

Often real devices can't be measured directly without including some simple circuitry at the input and the output to facilitate connection to a test apparatus. If the input and output circuits are known, class deembed can be used to deembed the tested device.

For example, a spiral inductor can't be measured directly. It might be wired bonded to some sort of coplanar waveguide substrate which can be probed on a network analyzer. In this case, the measured S parameters would be stored in a touchstone file. Variable "measured" would be an sdata_interp object that reads the touchstone file. Variable "input" would be a class cpw object representing the coplanar waveguide at the input (port 1) of the spiral, and "output" would be a class cpw object representing the coplanar waveguide at the output (port 2) of the spiral. A new deembed object created with these parameters would calculate the spiral inductor without the extra input and output circuits. 

      +----------------------------------------------------------+
      |                                                          |
      |                                                          |
      |   +-----------+     +-------------+     +------------+   |
 o----+---|           |--o--|             |--o--|            |---+----o
      |   |1  input  2|     |1  deembed  2|     |1  output  2|   |
 o----+---|           |--o--|             |--o--|            |---+----o
      |   +-----------+     +-------------+     +------------+   |
      |                                                          |
      |                       measured                           |
      +----------------------------------------------------------+

"measured" is the entire circuit, composed of the subcircuits "input", "deembed", and "output".

Class deembed only works if all circuits are two port devices.

Class deembed assumes that the device is passive at device::T to calculate the noise correlation matrix. If this is not true, then the noise correlation matrix will be wrong.

Definition at line 89 of file deembed.h.

Constructor & Destructor Documentation

deembed::deembed ( nport & input,
nport & output,
nport & measured )
 

Create a deembed instance.

Parameters:
input   the input circuit (usually a model)
output   the output circuit (usually a model)
measured   the entire circuit (usually measured with a network analyzer)

Definition at line 36 of file deembed.cc.

Member Function Documentation

void deembed::recalc ( ) [private, virtual]
 

Calculate the S and C matrices, assuming for the noise calculation that the device is passive at temperature device::T.

Reimplemented from nport.

Definition at line 59 of file deembed.cc.

void deembed::recalc_S ( ) [private, virtual]
 

The S matrix is calculted here.

Reimplemented from nport.

Definition at line 65 of file deembed.cc.

Referenced by recalc().

Matrix deembed::scat_to_abcd ( const sdata & sd ) [private]
 

Calculate a transmission matrix from a scattering matrix and its normalization impedance.

Parameters:
sd   contains the scattering matrix to be converted
Returns:
the corresponding transmission matrix

Definition at line 45 of file deembed.cc.

Referenced by recalc_S().

int deembed::size ( ) const [inline]
 

The number of ports of the deembeded circuit.

Class deembed only works for 2 port devices.

Returns:
the number of ports

Definition at line 109 of file deembed.h.

Member Data Documentation

nport * deembed::in [private]
 

The known input subcircuit.

Definition at line 115 of file deembed.h.

nport * deembed::meas [private]
 

The known entire circuit.

Definition at line 121 of file deembed.h.

nport * deembed::out [private]
 

The known output subcircuit.

Definition at line 118 of file deembed.h.

The documentation for this class was generated from the following files:

Please direct comments and corrections to supermix@submm.caltech.edu
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