Research On LFN Measurement Of Optical Modulator Driver And Its Application

With the rapid development of communication system, MMIC based on GaAs material has developed quickly and at the same time is required of higher reliability. Low frequency noise(LFN) has been applied to the reliability testing of electronic materials and devices due to its advantages of sensitivity, quickness and nondestructiveness. Research shows that the LFN characteristics of GaAs devices can be used to detect information related to traps and defects inside them and conduct reliability characterization. To this day, although there have been a large amount of LFN studies on discrete devices as well as its application in reliability field, few of them are about circuits and modules.In this paper, with optical modulator driver being research object, on the basis of LFN mechanisms and model of GaAs device, along with theoretical analysis of circuit structure, LFN measurements for two types of optical modulator drivers are carried out and LFN methods of reliability characterization of integrate circuits are explored.The major work accomplished and conclusions drawn in this paper include:(1) LFN mechanisms of active device in optical modulator driver, e.g. PHEMT, are theoretically investigated with LFN model and LFN equivalent circuit model established. Then circuit LFN model was built through analysis of specific circuit in the optical modulator driver.(2) LFN measurement system for optical modulator driver was designed, LFN of the samples measured under several bias conditions, LFN characteristics of them presented regarding the testing results.(3) Based on theoretical analysis and LFN measurement results, amplitude of1/f noise, band noise voltage and corner frequency of G-R noise were identified as reliability assessment parameters for optical modulator driver. And feasibility of them was verified through ESD experiment.