A Wide-Frequency Constant-Amplitude Transmitting Circuit for Frequency Domain Electromagnetic Detection Transmitter

Abstract

In this paper, a novel AC magnetic transmitter current source circuit is proposed for application of frequency domain electromagnetic method (FEM) prospecting. The proposed current source circuit is capable of generating high frequency and high constant amplitude currents, which are key technical problems for FEM. It is suitable for very wide frequencies. The main circuit of the proposed current source consists of a rising-edge enhancing unit, a constant current control unit, and a high voltage clamping unit. Large constant clamping voltage is applied during the rising edge and the falling edge of the alternating square current to obtain a high frequency and high linearity current source. On the current flat stage, the constant current unit provides the energy to the load to ensure the constant amplitude of the output current. Detailed operations of the proposed magnetic current source are given. Simulation and experimental results demonstrate that the proposed circuit achieves short reversal time, the linearity of the rising/falling edge, constant amplitude and low power loss. These are the desired characteristics of the ac square current source probing transmitter for the magnetic FEM applications.