PERFORMANCE TESTS
PHASE NOISE AND NON-HARMONIC SPURIOUS TESTS 4-13.
The Phase Noise test uses a phase noise measurement system and a low phase noise
reference signal generator to measure the UUT phase noise. Non-harmonic spurious
signals are measured with the phase noise measurement system and low phase noise
reference signal generator and are verified with an RF spectrum analyzer. (See
REMARKS).
REQUIREMENTS:
• Phase noise at frequency >512 MHz less than -124 dBc/Hz.
• Phase noise at frequency <512 MHz less than -130 dBc/Hz.
• Non-harmonic spurious signal <-100 dBc.
TEST EQUIPMENT:
• Phase noise measurement system
• RF spectrum analyzer
• High-frequency synthesized signal generator (HFSSG)
REMARKS:
An RF spectrum analyzer cannot be relied upon to make -100 dBc spurious
measurements due to the analyzer's own internal spurious signal below -100 dBc, at a
variety of RF frequencies. A phase noise measurement system (using a frequency
reference with <-100 dBc spurious) can be used reliably to indicate spurious signals.
However, depending on whether the spurious signal is single sideband or double
sideband, there may be a 6-dB error in the indicated amplitude. (Double sideband
phase modulated spurious signals are indicated accurately.)
For best accuracy, to use the phase noise measurement system to locate spurious signal
frequencies that appear greater than -106 dBc, then verify the amplitude using the
spectrum analyzer in a coherent narrow scan. Typically, the spectrum analyzer is set 20
dB off scale, causing the 50-dB reference line to be -70 dBc. With sufficiently narrow
bandwidth, a -110 dBc noise floor can be obtained.
PROCEDURE:
1. Connect the UUT RF OUTPUT to the phase noise measurement system. Connect
the HFSSG to the LO INPUT.
2. Program the UUT to +13 dBm and 640 MHz. Measure phase noise at 20 kHz
offset. Note the amplitude and offset frequency of spurious signals larger than -106
dBc for later verification.
3. Repeat step 2 at the following frequencies: 1024, 950, 850, 700, 550, 400, 320, 250,
160, 100,
80, 60, 40, 30, 20, 14
MHz.
4. Connect the UUT to the RF spectrum analyzer and verify the amplitude of the
recorded spurious signal by programming the spectrum analyzer step size to the
measured offset frequency (step 2) and stepping the analyzer plus and minus about
the carrier.
4-16
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