Mixer/Converter Setup

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

Note: Swept IMDx, IMx Spectrum, NFx are supported by PNA only. GCx is currently not supported on the M9370A/71A/72A/73A/74A/75A.

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 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 for PNA ARE compatible. However, *.mxr(x) files created in IMDx contain information that is NOT included with other *.mxr(x) files.

    External Sources

    A *.mxr(x) file includes an LO source name. However, It does NOT include the LO Source configuration.

     

    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.

     

    Mixer Setup tab help

    Converter Stages  Select either 1 or 2-stage converters.

    Hardware Configuration

    Add Source  Click to start the External Device Configuration dialog.

    DUT Ports

    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 Power  Sets the power level for LO1.

    LO2 Power  Sets the power level for LO2.

    Swept Power Settings Set the power sweep setting.

    Path Configuration (PNA only)  

     

    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: