New-Tech Europe Magazine | May 2018

Note that this setup requires a high pass filter with a frequency cutoff at 24 GHz to suppress the lower sideband of unconverted signal. Mini-Circuits can provide filters for this purpose on request. As an interesting extension, the user may replace the spectrum analyzer with an oscilloscope to perform time domain analysis or real time analysis on 5G signals. Case 2: Vector Network Analyzer Up/Down Converter The same components used in the previous case may also be utilized to extend the frequency coverage of a low-frequency Vector Network Analyzer (VNA). The configuration in Figure 4 allows precise measurement of scalar ratios such as insertion loss, gain, and insertion phase at high frequencies with a more budget-friendly, lower frequency VNA. A more advanced approach may be realized with a VNA that has direct receiver access. Theoretically, full vector corrected measurements would be possible with the setup in Figure 4, but the losses of the mixers (~8 dB conversion loss) are significant enough as to affect the internal couplers in the VNA and hinder accurate calibration. To address that problem, external couplers can be used after the mixers to improve overall system directivity and enable accurate vector calibration andmeasurement. Figure 5 shows such a setup with full vector calibration and measurement capability. Note that a 4-way, 40 GHz splitter is used in this case, and a 24 GHz LO source with +21 dBm power is needed to distribute the LO signal into 4 channels. The couplers should operate in the 24 to 30 GHz range with a coupling ratio

Figure 3: Functional block diagram of setup to test 28 GHz user equipment with 6 GHz spectrum analyzer and signal generator.

Figure 4: Functional block diagram of setup to perform scalar test between 24 to 28 GHz on DUT with 6 GHz Vector Network Analyzer.

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