Noise Sidebands Performance Test

This test verifies that the PSA meets its noise sidebands specifications. There are two solutions available for this test. The preferred solution uses a Wenzel Ultra Low Noise Reference Frequency Source. The alternate solution uses a PSG signal generator and a notch filter. If the Wenzel source is mapped, TME will select the Wenzel preferred solution. If the Wenzel source is not mapped, the test will use the PSG/notch filter alternate solution.

Preferred Solution — Wenzel Source

The Wenzel source is a fixed oscillator so the phase lock loops can be optimized for good close-in phase noise. It has a SAW filter to improve the far-out phase noise. This excellent performance allows this test to verify phase noise at all offsets from a signal frequency. Either Wenzel Rev C or Rev D specifications are sufficient for this test. The Wenzel output power is approximately +13 dBm so the source output will be attenuated with a 6 dB fixed attenuator. The DUT input power will be approximately +7 dBm. The attenuator will also provide a very stable output match to the DUT.

The DUT noise floor will be characterized so that the DANL data will be used for noise subtraction on the wider offsets. The noise subtraction is not necessary for the narrow offsets because the instrument DANL does not add errors to the Phase Noise.

If the power line frequency is 50 Hz a line related spur will appear at the 100 Hz offset. In order to avoid measuring this spur the Phase noise will be measured at 90 Hz and 110 Hz and the average of the two measurements will be reported as the 100 Hz Phase Noise.

The noise repeatability is defined as 0.8*(5.2 dB)/Sqrt(Sweeptime x RBW) (as described in Application Note 1303). The 100 Hz offset requires that the IF Bandwidth be set very narrow to avoid the power line spur. To keep the noise uncertainty low, the Sweeptime will be set so that the product of (Sweetime x RBW) is in the 200 to 600 range.

Alternate Solution — PSG Source with Notch Filter

The alternate solution will use a PSG source with a 1.0001 GHz notch filter. The PSG phase noise is typically specified above 100 kHz offsets. The filter provides approximately 20 dB additional rejection at offsets 100 kHz and greater. The source frequency is shifted to place the notch at the offset frequency being measured. The notch filter will attenuate the source phase noise so the DUT phase noise can be measured.

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Required Test Equipment

Connection Setups

Setup using a Wenzel source (preferred solution)

Test setup using a PSG signal generator and a notch filter (alternate solution)