Research And Design Of RF Power Amplifier Circuit

The RF power amplifier circuit designed in this paper is mainly used in the Overhauser magnetometer RF polarization circuit. Overhauser magnetometer is a kind of high precision static magnetic measurement instrument based on Overhauser effect principle. The magnetometer with high precision, high sensitivity and low power consumption, is widely used in space measurement, diurnalvariation observation, archaeological areas and so on. Compared with the traditional proton magnetometer, the key to the Overhauser magnetometer is the excitation of nitrogen oxygen free radical in solution, and the polarisability of the solution in probe is related to the frequency and the power of RF excitation signal. In the meanwhile, the accuracy of magnetometer and the signal to noise ratio of output signal are directly related to the polarisability of the solution. Therefore, the study of the RF excitation source is very important to Overhauser magnetometer.In this paper, we first introduce the background、types and application fields of magnetic prospecting. The basic principle of Overhauser magnetometer and the development at home and abroad on Overhauser magnetometer are presented. Then the basic theory of RF power amplifier circuit applied to Overhauser magnetometer, which prepares the ground for the design and realization of the RF circuit, is shown. What follows is a specific description of the circuit design and realization, including the design of power source, the design of RF signal source and the design of power amplification circuit. The output signal is tested and analyzed as well. Finally the RF circuit designed in this paper is successfully applied to JOM-2 type Overhauser magnetometer for field experiment research, and the influences of RF excitation frequency, RF excitation signal power, RF excitation signal polarization time and solution concentration in probe on the output signal intensity are discussed.In this paper, the design of the RF power amplifier circuit based on different RF sources, such as DDS, quartz crystal oscillating circuit and active crystal, is discussed. It can find the best excitation frequency and make contributions to realization the goals of low power consumption、miniaturization and high integration density of Overhauser magnetometer. And it pushes the producibility of the Overhauser magnetometer in China.