一种高性能激光器驱动电流源的设计

Design of high⁃performance laser current source

可调谐激光二极管吸收光谱(TDLAS)技术中系统响应速度大小取决于高频电流源频率的高低。而电流源工作于电流模式,对于轻负载情形,电路可以工作在很高的频率;当处于重负载情形时,电路难以做到很高的频率。为了提升驱动电流源的频率,文中设计一种高性能激光器驱动电流源。首先建立一种基本的用于TDLAS系统压控电流源的传递函数模型,并对该模型进行简化;然后分析电路产生震荡的原因,并提出一种基于奈奎斯特判据的环路补偿方法。将两片有环路补偿和无环路补偿的电流源PCB分别进行对比测试,测试发现有环路补偿的激光器电流源可以工作在100 kHz频率而不产生震荡,而没有环路补偿的PCB输出却叠加了一个高频极点。测试结果表明,文中电路模型输出和实际测试非常吻合,该电路工作于高频而不发生震荡的特性可以用于驱动激光二极管,还可进一步提高TDLAS系统的响应速度。

The system response speed in tunable diode laser absorption spectroscopy(TDLAS)technology is depended on the frequency of high⁃frequency current supply.To increase the frequency of the driving current supply,a high⁃performance laser driving current supply is designed.A new transfer function model of voltage control current source used to TDLAS system is established and simplified,the circuit oscillation reason is analyzed.A kind of loop compensation method based on Nyquist criterion is put forward.Two current source PCBs with loop compensation and without loop compensation are compared and tested respectively.It was found that the laser current source with loop compensation could work without oscillation at high frequency of 100 kHz,but a output of PCB without loop compensation high⁃frequency pole is superimposed when the PCB output without loop compensation is conducted.The testing results show that the circuit model is in good agreement with the actual test result.The circuit with the characteristic of working at high frequency without oscillation can be used to drive the laser test,which can further improve the response speed of TDLAS system.