iTMSA (Integrated True Mode Stimulus Application)

Important Note

When the first iTMSA measurement is created, an IFMUX Cal is performed, which takes a couple of minutes.

When finished, Exit then restart the VNA App.

If an IF board is replaced, this Cal should be performed again. To make this happen, delete c:\users\public\network analyzer\IFMUX.txt. When the next iTMSA measurement is created, the file will be recreated with new data.

How to create an iTMSA trace:

1. Preset the VNA

2. Then do the following:

Using Hardkey/SoftTab/Softkey

1. Press Meas > Balanced >  Topology....

Balanced DUT Topology / Logical Port Mapping (with iTMSA Option S9x460A/B) dialog box

Learn about iTMSA.

Topology

The following topologies are available in True Mode Stimulus.

• BAL  DUT has a single balanced port.
• BAL-BAL  DUT has two balanced ports.
• BAL-SE   DUT has one balanced port and one single-ended port.
• BAL-SE-SE - DUT has one balanced port and two single-ended ports.
• SE-BAL   DUT has one single-ended port and one balanced port.
• SE-SE-BAL - DUT has two single-ended ports and one balanced port.

• All SE
  (Changes all entries to Single-ended)

• All BAL
  (Changes all entries to Balanced)

• All Unused
  (Changes all entries to Unused) This is a convenience feature to help set up custom topologies, but it is not possible to have only Unused ports. If the OK button is clicked and all ports are listed as Unused, the topology will be set up to have 1 SE Port.

• Custom
  (Maps the physical VNA ports to a device of balanced and single-ended logical ports for multi-port systems with greater than 4 ports.)

A balanced port can be any one of four physical port combinations:

1 - 3

1 - 4

2 - 3

2 - 4

For more than 4 ports systems in M980xA, iTMSA works with "ALL BAL" or "Custom" topologies.

For multiport M980xA, there are more than two balanced ports. The true mode can be set by each balanced port.

SCPI/COM below can be used to control this setting.

SCPI: CALCulate<cnum>:FSIMulator:BALun:BPORt<pnum>:STIMulus:TRUe:STATe <bool> and CALCulate<cnum>:FSIMulator:BALun:BPORt<pnum>:STIMulus:TRUe:STATe?)

COM: (BalancedStimulus.BalancedPortTrueState(bpnum)

Port Z

Provide an enable for both Common and Differential Conversion and SE Port Z Conversion.

Complex Z Wave Normalization - Selects the wave normalization method.

Power Waves - Waves are computed according to Kurokawa's power wave definition.

Traveling Waves - Waves are computed according to a traveling wave definition.

Balanced Port  Shows all ports defined on the balanced topology page.

Default Z  Shows the default impedances that will be applied if the port Z conversions are not enabled. The SE Default Z always equals the System Zo defined for the VNA. The Differential and Common Default Z will display values calculated from the single-ended port impedances.

Converted Z  User may enter the real or imaginary component of the impedance.

Warning Dialog  The dialog is displayed if "Conversion" is enabled and "Apply Fixtures" is currently disabled.

Offset

Balanced Port  Set the phase or power offset for the balanced port.

True Mode  Shows whether True Mode is On or Off.

Power Offset  Specify power offset. Range is  +/- 20 dB. This is in addition to the power level that is specified using the Power and Attenuators dialog. Offset Power is NOT reflected on the power dialog nor on the X-Axis during a power sweep. A power offset may only be applied to a True Mode port.

Apply Power Offset as Fixture

When unchecked, output calculations are performed and displayed as though there is no stimulus power offset.

When checked, output calculations are performed and displayed using the power offset that is applied to the DUT. Use this setting to compensate for a component or fixture that may present a magnitude loss before the DUT.

Phase Offset  Specify offset for the balanced INPUT port. This is in addition to the standard offsets, which are 180° offset for the differential stimulus sweeps, and 0° for the common stimulus sweeps. A phase offset may only be applied to a True Mode port.

Apply Phase Offset as Fixture

When unchecked, output calculations are performed and displayed as though there is only the standard offset. Although additional Phase Offset is applied to the stimulus, it is ignored in the calculations of balanced differential and common mode output signals.

When checked, output calculations are performed and displayed using the actual phase offset that is applied to the DUT. Use this setting to compensate for a component or fixture that may present a phase delay before the DUT.

Sweep

• Available only when Sweep type = CW.

• Available ONLY for balanced pairs.

The phase of the selected active source port is swept relative to the phase of the other source port in the balanced pair. The active source port uses the logical port number.

Phase Sweep is similar to phase offset, except that for each data point, the phase 'offset' is incremented.

For example, with the topology that is selected in the above image: (Bal-Bal) Logical port 1 = VNA ports 1 and 3. For a phase sweep with 7 data points, from 0° to 180°, the phase difference between port 1 and port 3 increments 30° with each data point:

Enable Balanced Phase Sweep  Check to enable phase sweep for the specified port. If enabled and the VNA sweep type is not CW, the following dialog is displayed to turn on CW Sweep Type.

Start / Stop Phase  Enter phase values in degrees.  Each sweep will start and stop at these settings.

Offset as Fixture

In the following image, the VNA phase sweep is shown as a phase shifter that is "virtually" located EITHER before the reference receiver (top) OR after the reference receiver (bottom) - NOT BOTH.  This image is useful as a model ONLY.

Note: Beginning with firmware version A.14.00, the Enable Differential Source Only Mode feature has been changed to a SCPI-only feature.

One use for Phase Sweep

Do the following to find the best operating point:

1. Phase sweep port 3, from 0° to 180°.  Note the peak of Sdd21.  This finds the phase offset of the input differential port.  

2. Set port 3 fixed offset to the phase that has the highest Sdd21.

3. Then, phase sweep port 4 (balanced port 2) to find the phase offset of the output differential port.

4. Then set the port 4 to fixed phase offset found.  

This measures the best possible case Sdd21 for the DUT.

Power and Attenuation (with True Mode Stimulus) dialog box help  

When a True Mode Stimulus is selected in the Balanced DUT Topology dialog, the balanced ports are shown on the top rows of the dialog. The individual VNA port settings are displayed but can not be changed directly.

Port Powers Coupled  Check to couple all power settings for Balanced Port 1 and Balanced Port 2. Clear this box to make independent power settings for these logical ports.

State  Should be left in Auto for iTMSA measurements. Learn more about his setting.

Port Power  Set power for the balanced port. Power for VNA ports, shown below balanced ports, are set to 3 dB less, or half power. Power Offset is made in addition to this setting, and on only VNA port 3 and port 4. Offset Power is NOT reflected on this dialog nor on the X-Axis.

Start and Stop Power  Available when sweep type is set to power sweep.

Auto Range Check to allow the VNA to select the optimum attenuation value to achieve the specified test port power.  Clear to manually set the attenuation for each port. Type or select the attenuation value in the adjacent Attenuator Control box. When the attenuator setting of a logical port is changed, then the attenuators of the VNA ports associated with that logical port change to the same value.

Leveling Mode  Open Loop leveling is available only on ports 1 and 3.  Learn more.

Note: The range of leveled power (ALC range) for balanced ports is 3 dB higher than it is for each individual VNA port. For example, if a VNA source port with 0 dB attenuation will supply leveled power from -30dBm to +15dBm, then the balanced logical port has a range of -27dBm to +18dBm. Learn more about Leveled Power.

Create / Change Receiver Measurements (with True Mode Stimulus) dialog box help  

Click Activate

• For RATIOED measurements, Select a receiver for the Numerator and select a receiver for the Denominator.

• For UNRATIOED measurements, Select a test port receiver (A, B, C, or D) for the Numerator. Reference receiver measurements are NOT accurate.  Select 1 for the Denominator.

For example, with a Bal-Bal topology, the above selections show a R3/R1 measurement. R (reference) receivers measure the stimulus to the DUT. An R3/ R1 trace shows the difference between the two sources that comprise logical port 1. With Log format, a power offset between the two sources is visible. With Phase format, a phase offset is visible.

Source Port  Specifies whether a Differential stimulus or Common mode stimulus is used for the measurement.

• With Source Port 1 or 2 selected, then Differential stimulus is used for the unratioed measurement which causes 180° offset between the sources.

• • Source Port 1 = Differential stimulus on BAL1 port

  • Source Port 2 = Differential stimulus on BAL2 port

• With Source Port 3 or 4 selected, then Common mode stimulus is used for the unratioed measurement which causes 0° offset between the sources.

• Source Port 3 = Common-mode stimulus on BAL1 port

• Source Port 4 = Common-mode stimulus on BAL2 port

Measurement example for a 8 ports M980xA system:

a) with true mode on all balanced ports

Above trace are all ax/ay,x format. It follows the definition of common mode and differential mode in 4-ports system.

The “a5/a7,7” trace means Common-mode stimulus on BAL3 port.

b) with true mode turned off on balanced port 3

The “a5/a7,7” trace shows that the a5 and a7 are not controlled to 0 degree phase difference.