【摘要】 采用脉搏波阻抗谱法能够有效地减小个体差异和测量条件对阻抗测量的影响,是一种很有前景的血液成分无创检测方法.波阻抗谱测量系统需要两路同频严格正交信号源,且信号频率在要求范围内程控可调.采用直接数字脉搏合成技术,以DDS芯片AD9854为核心设计了用于脉搏波阻抗谱测量系统的恒流驱动信号源.实验结果表明:采用AD9854,电路设计简单,工作可靠,容易实现频率调整,频谱稳定度和精确度以及相位误差满足测量系统要求.更多还原

【Abstract】 The method of pulse impedance spectroscopy(PIS),by which the influence of individual impedance variance and measurement conditions on bio-impedance measurement effectively reduced,is a prospective approach for non-invasive blood components measurement.Two channel sinusoidal signals which must be strictly orthogonal and frequency programmable are needed in PIS measurement system.A circuit solution of signal generator based on digital synthesis(DDS) technology is presented the design of constant driving current for the dynamic pulse impedance spectroscopy.Cored with DDS AD9854 in which two internal high speed,high performance quadrature D/A converters employed,the signal source generates highly stable,frequency-phase amplitude-programmable sine and cosine outputs.Results show the circuit is simple and reliable,the frequency stability and phase error meet the demand of the DPIS system.更多还原