应用于肺部EIT系统的激励电流源设计  

Design of the Excitation Current Source Applied in Pulmonary EIT System

作　　者：侯海岭[1,2] 王化祥[2] 陈晓燕[1] 

机构地区：[1]天津科技大学电子信息与自动化学院,天津300222 [2]天津大学电气工程与自动化学院,天津300072

出　　处：《自动化仪表》2014年第1期81-83,87,共4页Process Automation Instrumentation

基　　金：国家自然科学重点基金资助项目(编号:50937005);天津市科委自然科学基金资助项目(编号:12JCYBJC19300)

摘　　要：针对医学EIT系统的激励电流源需具备输出阻抗高、相移小等要求,设计并实现了一种基于FPGA的激励信号源。通过采用泰勒级数修正的DDS IP核,提高了正弦信号的输出分辨率和无杂散动态范围(SFDR)。基于第二代电流传输器AD844设计的电压控制电流源增加了直流反馈单元和输入缓冲,具有输出阻抗高、相移小以及线性度好等特点。试验证明,该电流源基本满足了肺部EIT系统在10 kHz^1 MHz扫频范围内对激励信号源的要求。In accordance with the requirements of high output impedance and small phase shift, etc. , for excitation current source applied in medical EIT system, the excitation signal source based on FPGA has been designed and implemented. Through adopting the DDS IP core corrected by Taylor series, the resolution of output frequency of sinusoidal signal and spurious-free dynamic range （ SFDR ） are enhanced. Through adding DC feedback unit and input buffering, the voltage controlled current source designed based on the second generation current conveyor CCII AD844 features high output impedance, small phase shift and good linearity. The experiments verify that this current source basically meets the requirements of excitation signal source of pulmonary EIT system within 10 kHz - 1 MHz sweep frequency range.

关 键 词：电阻抗成像 泰勒级数插值 FPGA DDS DAC 

分 类 号：TH778[机械工程—仪器科学与技术]