Why not just use the spectrum analyzer industry. In applications such as imaging radar, mobile communications, satellite communications, and weather monitoring, the demand for pure spectrum signals is growing. This requires fast, accurate and reproducible characterization of signal generation equipment. A dedicated phase noise and amplitude noise measurement system is required, and the measurement noise floor is usually better than -180 dBc/Hz. What is needed are instruments for measuring the absolute phase noise of crystal oscillators (VCXO, OCXO), SAW oscillators, synthesizers, phase-locked loops and VCO (locked or free-running high-Q), as well as amplifiers and mixers , Divider and multiplier.

Why not just use the spectrum analyzer industry. In applications such as imaging radar, mobile communications, satellite communications, and weather monitoring, the demand for pure spectrum signals is growing. This requires fast, accurate and reproducible characterization of signal generation equipment. A dedicated phase noise and amplitude noise measurement system is required, and the measurement noise floor is usually better than -180 dBc/Hz. What is needed are instruments for measuring the absolute phase noise of crystal oscillators (VCXO, OCXO), SAW oscillators, synthesizers, phase-locked loops and VCO (locked or free-running high-Q), as well as amplifiers and mixers , Divider and multiplier.

Although a spectrum analyzer can be used to generate some characteristics, it is not very helpful for distinguishing amplitude and phase noise. Not only the amplitude and phase noise cannot be separated, but the dynamic range and noise floor of the spectrum analyzer are also insufficient. The phase noise of the internal local oscillators in spectrum analyzers is too high, and they lack resolution bandwidth. Therefore, a special system is needed that first demodulates and then analyzes the amplitude and phase noise separately.

How to measure the phase noise of a signal source by using a spectrum analyzer
Measuring signal source phase noise 1

solution

Anapico, headquartered in Switzerland, has produced the APPH series of automatic signal source analyzers, which separate amplitude modulation and phase modulation measurements, can independently measure very low noise levels (less than -180 dBc/Hz), and have active and non-active measurements. The ability component of the source to add noise. APPH analyzer can provide up to 30GHz measurement capability, and has a fully integrated cross-correlation system, which can respond to the most common phase, amplitude and baseband noise measurement problems, providing high accuracy and reproducibility, fast measurement speed, and high dynamic range And low system background noise, while still providing an affordable price for the laboratory and production environment.

system structure

The core engine of the APPH series combines low-noise analog receiver channels with advanced digital signal processing technology to provide fast and repeatable noise measurements. The proprietary FPGA-based FFT crossover analyzer processes 125MSa/s in real time, and can complete thousands of correlations and measurements below -170dBc/Hz in a few seconds. The APPH series controlled by LAN or USB can use a PC, laptop or tablet as the controller, so there is no need to integrate a Display, which can reduce product costs to the greatest extent and improve reliability at the same time.

Accurate calibration

Encapsulating the system in a compact fanless chassis can further eliminate stray signals as well as ground and power line loops. Another very important consideration is accurate calibration. Before leaving the factory, each instrument is calibrated according to traceable noise standards to ensure high-precision, consistent and repeatable results. Optionally, the instrument can provide calibration standards so that users can perform on-site performance verification at any time.

Measurement capability

The measurements supported by Anapico’s APPH instrument include: additive or absolute phase noise measurements using internal or external references, amplitude noise measurements, and other automatic measurements used to evaluate RF signal sources. For crystal oscillators, PLL synthesizers, clocks, phase-locked VCOs, DRO and other sources, you can easily perform SSB phase noise, amplitude noise, AM noise measurement, additive or residual noise characterization, and baseband noise measurement up to 30GHz. .

The phase noise data shown in Figure 2 is collected from a low-noise 100 MHz OCXO reference. The three traces shown are after the first association (green, after a measurement time of 12 seconds), 10 associations (blue, after 120 s), and 100 associations (red, after 20 minutes). ). After ten correlations or two minutes, the noise floor of the DUT reaches -180 dBc/Hz. For this ultra-low noise measurement, use an external reference source to obtain faster results. The sensitivity of a system running with an internal voltage reference depends on the carrier frequency and frequency offset range of the DUT.

How to measure the phase noise of a signal source by using a spectrum analyzer
Measurement signal source phase noise 2

Figure 3 shows the typical sensitivity of APPH when the internal signal source is used for measurement. It is assumed that the measurement time is about 24 seconds and the offset is 1Hz to 10MHz. However, APPH signal source analyzer can also measure the additive phase noise of amplifiers under different driving conditions, and the phase noise of frequency conversion equipment such as prescalers or mixers. In addition, amplitude noise measurement is also supported.

How to measure the phase noise of a signal source by using a spectrum analyzer
Measurement signal source phase noise 3

Figure 4 shows the 4 GHz amplitude noise obtained from a signal generator in Anapico, and shows traces with user-defined markers and pseudo lists. APPH can also directly access the FFT analyzer, which can perform noise analysis on the power supply voltage and control voltage. APPH6040 and APPH20G with extended offset range provide bandwidth over 40 MHz and transient measurement function.
Figure 3: Sensitivity of APPH with internal reference source (after 24 seconds).

How to measure the phase noise of a signal source by using a spectrum analyzer
Measuring signal source phase noise 4

in conclusion

The APPH series phase noise tester provides a complete measurement function, which can evaluate various RF signal sources. They provide comprehensive measurement functions, such as phase and amplitude noise measurement, residual noise characterization, and direct access to the FFT analyzer for baseband signal and LF noise analysis. Using proven cross-correlation measurement procedures and self-calibration routines, repeatable and accurate measurement results can be obtained even under varying environmental conditions. The automatic frequency acquisition and self-calibration function greatly simplify the use and scope of the instrument, thus realizing fast measurement and easy operation.

The Links:   TFD58W22MW NHD-320240WG-AFFH-TZ001-C