Opens a dialog to select a balanced port configuration and define reference impedances for balanced ports and to select the measured ports.
Balanced Ports and Port Groups
Selecting a balanced port configuration means that one or more pairs of physical test ports are combined to form logical (balanced) ports.
Unbalance-balance conversion is the simulation of one or more unbalance-balance transformers (baluns) integrated in the measurement circuit in order to convert the DUT ports from an unbalanced state into a balanced state and virtually separate the differential and common mode signals. The analyzer measures the unbalanced state but converts the results and calculates mixed mode parameters, e.g. mixed mode S-parameters. The balanced ports of the DUT are directly connected to the analyzer ports and no physical transformer is needed.
Measurements do not necessarily require all of the physical and logical ports of the network analyzer. To save measurement time, it is recommended to define the ports that are actually used in the current test setup (Define Measured Ports). Unused ports will not be considered for the calculation of mixed mode, Z- and Y-parameters.
Option R&S ZVA-K6 provides the true differential mode. The true differential mode extends the virtual differential mode described so far, where the analyzer generates an unbalanced stimulus signal and uses mathematical transformations to determine the balanced results.
The tabs of the Balanced Ports and Port Groups dialog are used to:
Select one of the predefined balanced port configurations (Predefined Configs).
Define a logical port based on two physical ports and independent reference impedances for the calculation of common mode and differential mode parameters (Def. Balanced Port).
Dissolve a single logical port so that the two involved ports are again used as physical ports (Dissolve Bal. Port).
Switch the True Differential Mode (option R&S ZVA-K6) on or off .
Define port groups in order to restrict the number of measured quantities and speed up the measurement (Define Port Groups).
Using balanced ports
The Predefined Configs tab of the Balanced Ports and Port Groups dialog provides the most commonly used balanced port configurations for the analyzer.
The port configurations are arranged in a scrollable list and selected with a mouse click. The resulting port number assignment is shown on the left-hand side of the Balanced Ports and Port Groups dialog and in the Port Configuration dialog.
Predefined Configurations
The number of type of predefined configurations depends on the port number of the analyzer.
The predefined configurations comprise the fully single-ended (unbalanced) case, where the logical ports correspond to the physical ports, and all balanced configurations where two adjacent physical ports are connected to a logical port. In addition configurations where one or more ports are excluded from the measurement are provided (see Measured Ports).
Example: 4-port analyzer
Fully unbalanced: Physical ports no. 3, 1, 4, 2 connected to logical ports (DUT ports) 3, 1, 4, 2.
One balanced port:
a) Physical ports no. 3 and 1 connected to logical port 1, remaining ports unbalanced.b) Physical ports no. 4 and 2 connected to logical port 2, remaining ports unbalanced.
Two balanced ports: Physical ports no. 3 and 1 connected to logical port 1, physical ports no. 4 and 2 connected to logical port 2.
In additional configurations one, two or three ports (marked as ) are excluded from the measurement.
To define a non standard configuration or use different port impedances, select the Def. Balanced Porttab.
Using predefined port configurations
Remote control:
SOURce<Ch>:LPORt<log_port> <phys_port1>,<phys_port2> (no extra command for predefined configurations) SOURce<Ch>:TDIF[:STATe] ON | OFF
The Def. Balanced Port tab of the Balanced Ports and Port Groups dialog defines new balanced port configurations and reference impedances for common and differential mode.
In principle, it is possible to combine any pair of two physical analyzer ports. An n-port analyzer supports a maximum of n/2 (n even) or (n – 1)/2 (n odd) logical ports.
Select Logical Port Number shows the current port configuration. Clicking the table cells updates the left Physical Port Numbers table and makes it easier to define new logical ports.
Physical Port Numbers provides two drop-down lists to select a pair of different physical ports to be combined to the balanced (logical) port.
Reference Impedances provides input fields for the differential and common mode impedances.
Reference impedance settings
The default reference impedance for a physical port is equal to the reference impedance of the connector type assigned to the port but can be defined as an arbitrary complex value (renormalization of port impedances). By changing the reference impedance, it is possible to convert the measured values at 50 Ω (75 Ω) into values at arbitrary port impedances. For details refer to Virtual Transform –Reference Impedances.
For balanced ports it is possible to define separate complex reference impedances for differential and for common mode.
The default values for the balanced port reference impedances are derived from the (real) default reference impedance of the physical analyzer ports (Z0 = 50 >Ω):
The default value for the differential mode is Z0d = 100 Ω = 2*Z0.
The default value for the common mode is Z0c = 25 Ω = Z0/2.
Using your own port configurations
SOURce<Ch>:LPORt<log_port> <phys_port1>,<phys_port2> SENSe:LPORT<log_port>:ZCOMmon <real> [,<imaginary] SENSe:LPORT<log_port>:ZDIFferent <real> [,<imaginary] SOURce<Ch>:TDIF[:STATe] ON | OFF
The Dissolve tab of the Balanced Ports and Port Groups dialog reestablishes a single-ended (unbalanced) port configuration where logical ports correspond to (single) physical ports.
Select Logical Port Number shows the current port configuration. Selecting a Logical Port # and clicking Dissolve reestablishes a single-ended (unbalanced) port configuration.
SOURce<Ch>:LPORt<log_port>:CLEar [ALL] SOURce<Ch>:TDIF[:STATe] ON | OFF
The True Diff Mode tab of the Balanced Ports and Port Groups dialog activates the true differential mode (option R&S ZVA-K6).
To activate true differential mode, a balanced port configuration must be active. Moreover, the two physical ports providing the true differential signal must be fed by independent sources.
The dialog provides the following additional settings for the true differential mode with a frequency converter. The frequency converter mode must be active to change these settings.
Receiver Frequency for True Diff Source Adjustment defines the receiver frequency which the analyzer uses to adjust the desired amplitude and phase of the true differential signal. The adjustment requires a measurement of the a- and b-waves at the physical ports which belong to the balanced converter port. By default the receiver frequency for the source adjustment is equal to the receiver frequency for measurement, to be defined in the Receiver section of the Port Configuration dialog.
True differential mode with frequency converters
If the frequency converter mode is combined with true differential mode, the analyzer generates a true differential or common mode stimulus signal at a calibrated reference plane which is located after two frequency converter ports. To achieve this, two frequency converters with independent sources are combined to form a balanced converter port. The frequency converters must provide the RF drive signal simultaneously so that a third, independent LO signal is required. This means that the standard test setup described in section Converter Control –Connecting the Frequency Converters must be replaced by the following scheme:
Depending on the network analyzer type and the number of independent sources available, different test setups are possible.
1.R&S ZVA24/40/50 with 4 ports
Ports 1 and 2 are driven by the same source (coupled ports); ports 3 and 4 by a different source. Possible connection: Analyzer port 1 to RF IN (converter 1), analyzer port 3 to RF IN (converter 2), the LO signal for both converters is provided by an external generator in combination with an external power splitter.
2.R&S ZVA67 with 4 ports
All ports are independent. Possible connection: Analyzer port 1 to RF IN (converter 1), analyzer port 2 to RF IN (converter 2), analyzer port 3 is not used, analyzer port 4 provides the LO IN signal for both converters (via an external power splitter). This corresponds to the standard connection of two frequency converters, if the true differential mode is not used.
3. R&S ZVT20 with 6 ports
Ports 1 / 2, 3 / 4 and 5 / 6 are coupled. Possible connection: Analyzer port 1 to RF IN (converter 1), analyzer port 3 to RF IN (converter 2), the LO signal for both converters is provided by analyzer port 5 in combination with an external power splitter.
The Define Port Groups tab of the Balanced Ports and Port Groups dialog selects the ports that are used for the measurement.
Measured Ports
Measurements do not necessarily require all of the physical or logical ports of the network analyzer. To save measurement time, it is recommended to restrict the measurement to the ports that are actually needed. Note that the analyzer will actually perform a measurement at each of the measured ports.
Unused ports will not be considered for the calculation of mixed mode, Z- and Y-parameters.
The measured ports are indicated in the first column of the Port Configurationtable (Meas). The ports can be either source ports or receive ports.
Port Configuration shows the current physical and balanced ports and the measured ports (Meas). If Simultaneous Measurement of Port Groups is active, the table shows the defined port groups (A, B...).
Simultaneous Measurement of Port Groups activates the definition of one or more groups of ports that can be used for parallel measurements (see background information below).
Port Groups shows the existing port groups, each consisting of a continuous range of measured ports. Selecting another First Port or Last Port changes the range. To avoid ambiguities the ports are always logical ports.
If a frequency-converting mode is active, port groups cannot be measured in parallel.
Simultaneous Measurement of Port Groups
A port group is a continuous range of measured ports which is labeled with a capital letter. The analyzer can measure several port groups in parallel. Port groups must not overlap and contain at least one logical port, so the maximum number of port groups is equal to the number of ports of the analyzer.
Example: Using port groups on a 4-port analyzer
A 4-port analyzer can be used for parallel measurements if only 1-port, 2-port or 3-port parameters are needed:
Combining ports 1 and 2 to a first port group, ports 3 and 4 to a second port group leaves two sets of 2-port parameters to be measured in parallel. The measurement provides 2 * 4 = 8 S-parameters and is faster than a full 4-port measurement (16 parameters).
A reflection measurement involving four port groups, each with a single port, provides 4 parameters and is faster than the measurement with two groups of 2 ports.
The defined port groups are indicated in the first column of the Port Configurationtable (Meas). Selecting Simultaneous Measurement of Port Groups enables two additional buttons:
Add Group adds a new group (with default ports, depending on the existing port groups) to the Port Groups table.
Delete Group deletes the selected group.
Always select the balanced port configuration before defining port groups. When a new balanced port is created, the analyzer deactivates Simultaneous Measurement of Port Group and deletes all existing port groups. In remote control, you can create a port group with an arbitrary, not necessarily continuous port range.
SOURce<Ch>:GROup<group_no> <log_port1>,<log_port2> SOURce<Ch>:GROup<group_no>:CLEar [ALL] SOURce<Ch>:GROup<group_no>:COUNt SOURce<Ch>:GROup<group_no>:PORTs SOURce<Ch>:TDIF[:STATe] ON | OFF