High-speed digital-controlled variable voltage source with current monitor for EIT application

This paper presented the design method of a digital-controlled variable voltage source with current monitor function. The hardware of system mainly consists of FPGA, DAC, programmable gain amplifier, current sensing circuit and comparator. By using high-speed analog comparator to convert over-current time to length of digital pulse, the FPGA could monitor the amplitude of current dynamically. In aspect of software, CORDIC algorithm is implemented in FPGA to realize the DDS function and related algorithms. Simulation result shows that system has good performance over wide frequency range. With the advantages of accuracy and high stability, it is suitable for EIT application.