Design Of High Precision Programmable DC Current Source Module

Source Measure Unit（SMU）is a new type of instrument that integrates a signal source,a multimeter and an electronic load.With its ability to provide and measure voltage or current signal,SMU can complete a variety of test work in one instrument.It has excellent performance and high intelligence,which is widely used in various high precision measurement systems.The high precision and program-controlled DC current source module is an important part of the SMU system,which is responsible for outputting constant current and measuring the output signal synchronously.In order to ensure the smooth progress of SMU research and improve its performance,it is significant to design a DC current source module with high output precision,high reliability,and simplicity of using.Thesis takes the design of high precision and program-controlled DC current source module as the research topic,which is focused on four parts: high precision current output method,data processing and transmission,instrumental control logic and human-computer interaction:1.In terms of high precision current output method,a hardware system based on STM32F103 microprocessor as the control core is designed,and the programming control and precise self-regulation of current output are realized through digital control and closed-loop feedback circuit,which effectively avoid disadvantages in the pure analog control method of traditional current source;2.In terms of data processing,the measured readback data is filtered by dynamic window sliding average,taking into account the filtering effect and dynamic response.And the linear interpolation algorithm is used to calibrate the systematic error.The data is organized and managed by setting up a double-buffered FIFO ring queue,and the parallel control of data transmission by CPU and DMA is used to improve communication efficiency.3.In terms of instrumental control logic,the software is divided into three layers from top to bottom,based on the idea of hierarchical design: application layer,instrument layer and driver layer.Clear division of labor and mutual cooperation between all layers ensure the orderly and efficient operation of the software system.4.In terms of human-computer interaction,two modes are designed,one is local operation on the embedded panel,the other one is remote operation on the computer.Users can control current output and modify system parameters through the interactive terminals,and can also read the information of real-time working status of the system on the interactive interface.Thesis analyzes the hardware and software design scheme of the high precision and program-controlled DC current source in detail,and confirms that its functions and performance indicators meet the requirements by testing,which can be used as a current source module in the system of SMU.