Mixer/Converter Setup

The following dialogs are common to all Converter Apps: FCA, Swept IMDx, IMx Spectrum, NFx, and GCx applications.

Important Note: Connecting your Mixer/Converter DUT to the VNA.

RF and IF terminology is NOT used in this topic because the VNA does not know how your DUT is labeled or how it will be used. Instead, the general terms INPUT and OUTPUT are used to describe the following VNA behavior:

  • INPUT - the stimulus frequencies BEFORE conversion by your DUT.

  • OUTPUT - the response frequencies, AFTER conversion (either UP or DOWN) by your DUT. Specify UP or DOWN conversion using the + or - symbol for each output.

 

Mixer Frequency tab help

Settings

Frequency Format   Select Start/Stop (Swept) or Fixed. For Linear sweep type, at least one of these must be fixed. For CW or Power, ALL must be Fixed.

Frequencies  Enter the frequency values for each of the Mixer/Converter ports.

Mixer-Product Selector  Determines whether the receivers will tune to the Sum (+) or the Difference ( - ) of the Input and LO frequencies.

Calc buttons  Calculates frequency settings based on your other mixer settings. For example, enter the Input frequency range and LO1 frequency range, then press Calc Output.  The VNA will calculate and display the Output frequencies.

Input > LO or IF1>LO2  Removes ambiguity when using a Calc button to determine the INPUT frequency.

These check boxes are used ONLY when all 3 of the following conditions are TRUE:
(If ALL 3 are NOT true, the VNA does not read these check boxes).

  1. Difference (Low) sideband is selected for the corresponding Calculate button AND

  2. Output frequency is less than the LO frequency AND

  3. One of the Calculate buttons are used to calculate the Input frequency.

Rules for Configuring a Mixer

A Red message across the bottom of the dialog indicates that one or more of the following settings are invalid:

  • Either ALL ranges (Input, LO, Output) must be Fixed, or ONE Range fixed. TWO ranges can NOT be Fixed or THREE ranges can NOT be Swept.

  • For determining a valid mixer configuration with 2 LOs, one Fixed LO and one Swept is equivalent to having a single-stage Swept LO. To configure a 2-stage LO, select Converter Stages: 2 on the Mixer Setup tab.

  • INPUT or OUTPUT frequencies cannot be outside the range of the VNA.

  • Any combination of INPUT and LO which results in an OUTPUT that sweeps through Zero Hz is NOT allowed.

About Mixer Configuration Files (.mxr and *.mxrx)

 

 

Save  Saves SOME of the mixer settings to a *.mxr or *.mxrx file.

Load  Recalls a previously-configured mixer *.mxr or *.mxrx file .

Note: By default, mixer configurations are saved to a *.mxrX file. Previously, they were saved to a *.mxr file.

ONLY *.mxrx files allow saving segmented sweep mixer setups. Currently, only FCA allows segmented sweeps. In all other respects, these new file types are completely backward compatible with *.mxr files.

What Mixer Settings are Saved?

  • Sweep Type, frequency, and power settings.

  • With Segment Sweep Type, all segment settings are saved.

Converter App Compatibility

The mixer setup files that are used with FCA, NFx, and GCx ARE compatible. However, *.mxr(x) files created in IMDx contain information that is NOT included with other *.mxr(x) files.

  • When *.mxr(x) files created in other apps files are recalled into IMDx, the PNA-X attempts a 'best guess' at missing information.

  • When IMDx *.mxr(x) files are recalled into other apps, the extra information is ignored.

  • When *.mxr(x) files are recalled into an IMx Spectrum channel with any range being swept, the recall is ignored and an error message appears.

External Sources

A *.mxr(x) file includes an LO source name. However, It does NOT include the LO Source configuration. Therefore, when using a *.mxr(x) file that was created on a different PNA, the PNA-X will display an error if does not find the LO Source configuration using EXACTLY the same LO source name.

 

Apply  Applies the settings for your mixer/converter test setup to the measurement. The mixer setup dialog box remains OPEN.

OK  Applies the settings for your mixer/converter test setup to the measurement. The mixer setup dialog box CLOSES.

Cancel  Closes the mixer setup dialog box and does NOT apply the settings.

See Also

How to measure a DUT with an Embedded LO

 

Mixer Setup tab help

Note: A variation of this dialog is used in the Swept IMDx application.  Learn more.

Converter Stages  Select either 1 or 2-stage converters.

Hardware Configuration

Shows the path configuration for Port 3 and Port 4 switches. See Hardware Configurations.

Add Source  Click to start the External Device Configuration dialog.

Path Configuration  Click to start the Path Configuration dialog.

DUT Ports

VMC ONLY - select the PNA port to connect to the DUT output. The DUT input must always be connected to PNA port 1 because of the need for a reference mixer on port 1.

All other converter applications - select VNA ports to connect to the DUT input and output.

Fractional Multipliers

The combination of (numerator / denominator) forms a fractional value that is multiplied by the input and LO frequency ranges. These values are used to calculate the response frequency of the VNA receiver for the converter output. Use the fractional multipliers to:

  • simulate the action of harmonic mixers

  • simulate the action of multipliers and dividers that may exist in your test setup

  • tune the VNA receiver frequency to a harmonic of the mixer/converter

The range for the numerator and denominator of a fractional multiplier is from +1 to +10. Negative values are NOT allowed.

See Fractional Multiplier examples.

LO1 and LO2

Select Not controlled to allow an external source to provide a Fixed LO Frequency at all times. Otherwise, select an internal VNA source or External source to be used as the LO. Learn how to Configure an External Device (Source).

See Also

How to measure a DUT with an Embedded LO

Learn about these buttons.

 

 

Mixer (LO) Power tab help

Configures LO Power settings.

Power ON (All channels)  Check to immediately turn ON or OFF ALL VNA internal RF Sources for all channels.

LO1: <source> Power Settings

LO1 Power  Sets the power level for LO1.

Source Leveling   When using internal source for LO1, always set to Internal.

LO2: <source> Power Settings

LO2 Power  Sets the power level for LO2.

Source Leveling   When using internal source for LO2, always set to Internal.

Port Settings

Port 3   Used when an LO is supplied through the rear panel and out port 3. See Hardware Configurations.

Source Attenuator  Specifies the port 3 attenuator. This attenuator affects the range of available power into the LO port of the DUT Learn more about Source Attenuation.

Receiver Attenuator  Set the attenuation for the Port 3 receiver. Learn more about Receiver Attenuation.

 

Port 4   Used when an LO is supplied through the rear panel and out port 4. See Hardware Configurations.

Source Attenuator  Specifies the port 4 attenuator. This attenuator affects the range of available power into the LO port of the DUT Learn more about Source Attenuation.

Receiver Attenuator  Set the attenuation for the Port 4 receiver. Learn more about Receiver Attenuation.

 

Path Configuration  Click to launch the RF Path Configuration dialog.

 

Note:  VMC measurements using a PNA-X with Internal Second Source

Source 2 is automatically configured to supply power to BOTH available ports simultaneously. This setting can NOT be changed.

In addition, power can be uncoupled to provide different power levels at each port This feature allows power to be delivered to both the DUT LO and Reference Mixer LO without use of a splitter. See VMC setup.

See Also

How to measure a DUT with an Embedded LO

Learn about these buttons.

 

Fractional Multiplier Examples

Example 1

Use the LO fractional multiplier to replicate the action of the third-harmonic mixer so the VNA can accurately calculate the receiver frequency. The input and LO frequencies are known.

Enter these settings in the Mixer Setup dialog box:

Click Calculate Output

Results:

Example 2

Use the fractional multipliers to tune the VNA receiver frequency to the second harmonic of the mixer's 14 GHz fundamental output. The input, LO, and output frequencies are known.

Enter these settings in the Mixer Setup dialog box:

Click Calculate Output

Results:

Example 3

Use the LO fractional multiplier to replicate the action of the divide-by-two mechanism inside the mixer package. Having done this, the VNA can accurately calculate the receiver frequency. The input and LO frequencies are known.

Enter these settings in the Mixer Setup dialog box:

Click Calculate Output

Results: