Principle of RF Signal Generator

　　Main components

　　Oscillator: The most important component in an RF signal generator, which receives commands from the controller to set the required frequency for output

　　Amplifier: amplifies the output signal of the oscillator to a specific power level

　　Attenuator: helps to ensure impedance matching at the output end of the RF signal generator, and can also ensure stable output level accuracy of the signal source by automatically adjusting the attenuator. Generally, the incremental step of the attenuator is 0.1dB

　　Control: The control center of the RF signal generator controls the output frequency, output power, modulation method, and can also receive remote control commands.

　　Modern frequency synthesis technology often uses indirect synthesis method, which links the frequency of the main vibration source and the frequency of the reference frequency source through a phase-locked loop. It requires less hardware equipment, high reliability, and a wide frequency range.

　　The signal of the tuned oscillator, after passing through the feedback network, and the signal of the reference frequency source, are output as an influence voltage in the frequency/phase detector. After passing through a loop filter as the tuning voltage, the frequency of the tuned oscillator is corrected. When it reaches a stable state, the difference between the two frequencies is zero, forming phase locking.

　　A loop filter is a low-pass filter with a certain gain, which can filter out the phase detection frequency and its harmonics to obtain the optimal phase noise of the tuned oscillator output frequency.

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