Five Methods to Improve the Performance of RF Signal Generators

　　Many economical RF signal generators have technical parameters that can basically meet basic applications. But for some higher professional fields, there are still some gaps in key indicators. So, how can we effectively improve the performance of RF signal generators and expand their application scope while saving budget?

　　A high-precision RF signal generator can also serve as a standard signal source (reference source) in the field of metrology and calibration, and the instrument to be calibrated is calibrated using the reference source as the standard. From this, it can be seen that signal generators can be widely used in electronic research and development, maintenance, measurement, calibration and other fields.

　　1. By using an external power meter, the amplitude accuracy of the RF signal generator can be improved.

　　Due to the output amplitude accuracy of the signal generator itself and the frequency response characteristics of the connecting components between the signal generator and the tested component, the signal amplitude reaching the tested component may have a greater error than expected.

　　2. By connecting high-precision constant temperature crystal oscillators externally, the stability of the RF signal generator is improved and the level of near end phase noise is improved.

　　The factor that determines the frequency accuracy and stability of a signal generator is the reference crystal oscillator used by the machine. Due to cost considerations, economical signal generators generally do not use expensive constant temperature crystal oscillators. However, in certain special testing scenarios, we will pay close attention to the absolute frequency accuracy of the signal generator or the stability caused by drift over time and temperature. At this time, we only need to purchase a high-precision constant temperature crystal oscillator option separately as an external reference for the signal generator, which can effectively solve this problem.

　　In addition, when the frequency offset is less than 1kHz, the stability and phase noise of the signal generated by the signal generator will be mainly determined by the reference clock. Using high-precision constant temperature crystal oscillators is beneficial for improving the near end phase noise level of the signal.

　　3. Reducing harmonics and spurious signals in RF signal generators through external low-pass filters

　　When the signal generator outputs the set fundamental signal, it is accompanied by a certain amplitude of harmonics, subharmonics, and clutter signals. In most cases, we do not need harmonic components, or the presence of these harmonic components can cause certain interference to normal testing.

　　We choose a suitable low-pass filter to connect to the output of the signal generator based on the actual testing situation, which can effectively filter out high-frequency harmonic components and improve the spectral purity of the signal.

　　Connecting a low-pass filter inevitably affects the amplitude and flatness of the output signal. We can compensate for flatness and accuracy by increasing the output signal level and connecting an external USB power meter.

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