Design of RF amplifier based on direct digital synthesizer output
Bin Qin · High Power Laser and Particle Beams · 2008
As a new RF generator,the direct digital synthesizer(DDS) has been widely used.In order to reduce the high cost of the signal generator comprising a high performance DDS device,the method of picking-up a desired aliased signal DDS output is adopted in the design.A device of AD9850 is used to generate RF signal in the system,and the amplitude modulation of the system is achieved by using a voltage variable attenuator.The amplifier based on tetrode is selected to get an output power of 10kW at(96±1) MHz.Amplifier operates in a grounded cathode configuration.A short-circuited coaxial transmission line is adopted in both input circuit and output circuit.The PID-control strategy has been used in control system,and the relay method has been used for measurement.The controller has a built-in auto-tuning function which allows the PID parameters to be determined automatically using the Ziegler-Nichols method.