skrf.calibration.deembedding.IEEEP370_MM_NZC_2xThru

class skrf.calibration.deembedding.IEEEP370_MM_NZC_2xThru(dummy_2xthru, name=None, z0=50, port_order='second', use_z_instead_ifft=False, verbose=False, forced_z0_line_dd=None, forced_z0_line_cc=None, *args, **kwargs)

Creates error boxes from a 4-port test fixture 2xThru.

Based on [ElSA20] and [I3E370].

A deembedding object is created with a single 2xThru (FIX-FIX) network, which is split into left (FIX-1_2) and right (FIX-3_4) fixtures with IEEEP370 2xThru method.

When Deembedding.deembed() is applied, the s-parameters of FIX-1 and FIX-2 are deembedded from the FIX_DUT_FIX network.

This method is applicable only when there is a 2x-Thru measurement.

The S-parameters bisection is done by time gating S11 and S22, taking the proper square root of the S21 corrected by return loss, and remixing the parameters according to the fixture signal flow graph. This method gives crude results but is robust.

Note

The port_order =’first’, means front-to-back also known as odd/even, while `port_order`=’second’ means left-to-right also known as sequential. `port_order`=’third’ means yet another numbering method. Next figure show example of port numbering with 4-port networks.

The scikit-rf cascade ** 2N-port operator use second scheme. This is very convenient to write compact deembedding and other expressions.

numbering diagram:

port_order = 'first'
     +---------+
    -|0       1|-
    -|2       3|-
     +---------+

port_order = 'second'
     +---------+
    -|0       2|-
    -|1       3|-
     +---------+

port_order = 'third'
     +---------+
    -|0       3|-
    -|1       2|-
     +---------+

use Network.renumber to change port ordering.

Example

>>> import skrf as rf
>>> from skrf.calibration import IEEEP370_MM_NZC_2xThru

Create network objects for 2xThru and FIX-DUT-FIX

>>> s2xthru = rf.Network('2xthru.s4p')
>>> fdf = rf.Network('f-dut-f.s4p')

Create de-embedding object

>>> dm = IEEEP370_MM_NZC_2xThru(dummy_2xthru = s2xthru, name = '2xthru')

Apply deembedding to get the actual DUT network

>>> dut = dm.deembed(fdf)

Note

numbering diagram:

 FIX-1_2  DUT      FIX-3_4
 +----+   +----+   +----+
-|1  3|---|1  3|---|3  1|-
-|2  4|---|2  4|---|4  2|-
 +----+   +----+   +----+

Warning

There are two differences compared to the original matlab implementation [I3E370]: - FIX-2 is flipped (see diagram above) - A more robust root choice solution is used that avoids the apparition of 180° phase jumps in the fixtures in certain circumstances

References

[ElSA20]

Ellison J, Smith SB, Agili S., “Using a 2x-thru standard to achieve accurate de-embedding of measurements”, Microwave Optical Technology Letter, 2020, https://doi.org/10.1002/mop.32098

[I3E370] (1,2)

https://opensource.ieee.org/elec-char/ieee-370/-/blob/master/TG1/IEEEP370mmZc2xthru.m commit 49ddd78cf68ad5a7c0aaa57a73415075b5178aa6

Parameters:

• dummy_2xthru (Network)

• name (str)

• z0 (float)

• port_order (PortOrderT)

• use_z_instead_ifft (bool)

• verbose (bool)

• forced_z0_line_dd (float)

• forced_z0_line_cc (float)

Methods

COM_receiver_noise_filter	receiver filter in COM defined by eq 93A-20 As defined in 802.3-2022 - IEEE Standard for Ethernet annex 93A
DC	Advanced reflective DC point extrapolation.
NRP	Enforce the Nyquist Rate Point.
__init__	IEEEP370_MM_NZC_2xThru De-embedding Initializer
add_dc	Extrapolate a network to DC using interpolation for all S-parameters.
dc_interp	enforces symmetric upon the first 10 points and interpolates the DC point.
deembed	Perform the de-embedding calculation
extrapolate_to_dc	Extrapolate the network to DC using IEEE370 NZC algorithm.
getz	Compute step response to get the time-domain impedance from S-parameters.
makeStep	Make a time-domain step response from an impulse response.
makeTL	Compute the S-parameters of a transmission line.
peelNPointsLossless	Peel N points of the network on both side and return the corresponding error boxes.
plot_check_impedance
plot_check_residuals
shiftNPoints	Shift the whole network of N samples in time-domain.
shiftOnePort	Shift one port of the network of N samples in time-domain.
split2xthru	Perform the fixtures extraction.
thru	Create a perfect thru