Understand the operation of the generic microwave or RF signal generator it is useful to understand what is included in terms of a basic block diagram.
Above diagram shows a very simplified block diagram for the RF / Microwave signal generator. This can be seen that the signal generator has a four major blocks within it:
Oscillator is the most important block within the RF signal generator, it is the oscillator itself. It can be any form of oscillator but today it would approximately certainly be formed from the frequency synthesizer. This oscillator unit would take commands from the controller unit and be set to the required frequency.
Amplifier is the output from the oscillator and it needs amplifying. This can be achieved by using the special amplifier module. This unit will amplify the signal, typically to the fixed level. It would have a loop around it to maintain the output level precisely at all frequencies and temperatures.
Attenuator is placed on the output of the signal generator. This serves to ensure the accurate source impedance is maintained as well as allowing the generator level to be adjusted very accurately. In particular the relative power levels, when changing from one level to another are very accurate and represent the accuracy of the attenuator. It is worth noting that the output impedance is less accurately defined for the highest signal levels where the attenuation is less.
Control is advanced processors and it is used to ensure that the RF and microwave signal generator is easy to control and is also able to take the remote control commands. The processor will control all features of the operation of the test equipment.