Analysis of the three major architectural elements of RF signal sources

博宇讯铭

Analysis of the three major architectural elements of RF signal sources [Copy link]

Engineers are familiar with RF signal sources, which are often used to calibrate spectrum analyzers, modulation analyzers, power meters, frequency meters, RF millivolt meters, high-frequency digital oscilloscopes and many other RF radio measurement instruments. They are widely used in production testing, laboratories, medical communications, industrial control, military and aerospace. So, how much do you know about the internal architecture of RF signal sources?

In order to help you better understand the RF signal source, Boyu Xunming engineers explain the "decomposition" of the RF signal source. Today, let's take a look at the three major architectural elements of the RF signal source and what their functions are.

RF signal generators have always been a staple in test and measurement. Over a long period of time, they have evolved in countless ways, but the basic principles remain the same. Whether the RF signal generator is used to generate continuous wave (CW) signals or includes analog or digital modulation, the RF signal source has three basic architectural elements: the reference section, the synthesis section, and the output section. As shown in the figure:

The reference source , that is, the reference local oscillator, is the key factor in determining the output frequency accuracy. Its core is a reference oscillator, which must be very stable. Its stability will ensure that the frequency output of the signal source remains accurate and determines the overall phase noise level of the instrument.

The synthesis part of the signal generator directly or indirectly uses one or more reference oscillators to produce the required operating frequency range. It is divided into direct analog synthesis and direct digital synthesis.

Direct analog synthesis uses a set of oscillators that are multiplied, divided, mixed, and then filtered to produce a range of output frequencies.

Direct digital synthesis (DDS) instruments use a reference oscillator to record digital circuits that include a digital-to-analog converter (DAC) to directly generate the desired output frequency.

Another method is indirect synthesis, which uses VCO or YIG, YTO to generate the required output frequency.

The output section of the signal generator maintains the desired output amplitude by measuring the output power and compensating for deviations from the set power level. The automatic level control (ALC) circuit samples the signal generator output power and adjusts the gain or attenuation to maintain the output power expected by the user.

Of course, in order to measure more accurately, the RF signal source includes not only the above three components, but also amplifier circuit, display circuit, signal storage circuit, etc. These components are also very important. If you still have questions about the RF signal source, you can contact Boyu Xunming Engineering, which will help you provide a better test solution to make your test easier.