一种频率可调的程控精密恒流源设计

Design of programmable constant current source with adjustable frequency

针对生物电阻抗谱测量需求,设计一款频率可程控调节的精密恒流源,给出频率可调程控精密恒流源的构成框图,并详细介绍基于单T选频网络的信号源电路设计和基于改进型Howland电流泵的电压电流转换电路设计。仿真实验表明:程控精密恒流源在200~500 k Hz频率范围、10Ω~1 kΩ的负载范围下的电流波动在1.63%以内。电路频率调节便捷、输出阻抗高、负载能力强、输出电流稳定,已应用于肉类水分快速测定仪和注水肉快速测量仪。

Aiming at the demand of bioelectrical impedance spectroscopy,a precision constant current source with programmable frequency adjustment was designed,and the block diagram of this constant current source was given.The design of signal source circuit based on single T frequency selective network and the design of voltage-to-current(VTC)converter circuit based on improved Howland current pump were both introduced in detail in this paper.According to the simulation results,the current fluctuation of the programmable precision constant current source in the frequency range of 200–500 kHz and the load range of 10Ω–1 kΩis less than 1.63%.With the convenience of frequency adjustment,the high output impedance,the strong load capacity and the stable output current,this circuit has been applied to rapid meat moisture analyzer and rapid water-injected meat measurement instrument.