China Electronics Technology Instruments AV3672 Series, User Manual

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Appendix
Appendix 6 Mixer Measurement
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Fig. 6.25 [Vector mixer calibration] Dialog Box
5) [Help] dialog box for saving of mixer characteristics
The vector network analyzer has the function to save characteristic data of the calibration mixer. After calibration,
the mixer characteristic calibration file will be saved to the specified path. If the same calibration mixer is used in
vector mixer measurement calibration, the saved S2P file can be recalled directly.
Fig. 6.26 [Save characteristics] Dialog Box
Browse: find the path to save the characteristic data of the calibration mixer. Use the default or custom name.
Next: click [Next] to complete system calibration after saving the characteristics of the calibration mixer.
6.6 Embedded LO Mixer Measurement
A fixed LO is embedded in the tested mixer. The characteristics of the embedded LO can be applied in vector
mixer, scalar mixer measurement, IMDX, IMXSpectrum, GCX and NFX measurement.
It is challenging to measure such devices for the following two reasons.
1) The reference mixer with the same LO frequency is required in vector mixer measurement. The independent
internal source or external source must be used as LO of the reference mixer. At the same time, LO is controlled by
the instrument. The measurement velocity is higher if the internal source 2 is used.
2) All the embedded LO measurement must be adjusted with the analyzer receiver to the exact frequency to
measure the mixer output. Thus the LO frequency must be accurate.
1) How to measure the embedded LO?
Enter the nominal frequency of the embedded LO in the [Mixer setting] dialog box, as the start point of
measurement.
Before measurement sweep of the DUT, start background sweep to determine the frequency of the embedded LO
obtain the configurable accuracy. Background sweep:
1) Broadband sweep: initially measure the embedded LO frequency, and add one frequency range near the selected
data point. The input signal of the DUT must be selectively adjusted to CW. Receiver B is used to sweep the
selected frequency range near the preset output frequency. Obtain the desired difference between the output signal
and the found frequency, and apply the obtained result in adjustment.
2) Accurate sweep: Receive B is used to measure the selected data point. Measure the ratio of the phase and time,
and calculate the exact frequency offset, until reaching the allowable residual value or maximum degree of
repetition.