| 摘要 |
The RF power amplifier (PA1) of the system comprises a bridge-type circuit comprising a first switch with transistors (70,76) and a second switch with transistors (72,74) and a control circuit for the provision of on-state signals for the passage of RF pulses to switches, including logic gates (300,310,320,330) connected to the first and second switches by the intermediary of buffer amplifiers (210,212,214,216) and inductive switching devices (250,252,254,256). A synchronous insulated power supply (220) provides a current in one direction or the other through a load as e.g. antenna connected to the secondary coil of transformer (T1), and supply voltages to the buffer amplifiers. Each inductive switching device (250,252,254,256) comprises a resistor and an inductor connected in parallel, a damping circuit comprising a diode-resistor and a capacitor-resistor branches, a transistor and a control circuit. The logic circuit responds to the control signal so that the first and the second switches are set in on-state and in off-state in synchronization with the start and the stop of the RF cycle. The synchronous insulated power supply (220) comprises a transformer with a primary coil and a set of secondary coils, and switching transistors connected to the primary coil and controlled in synchronization with the RF pulses. The transistors are of Metal-Oxide-Semiconductor Field-Effect-Transistor (MOSFET) type.
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