Research On AGC System Design And Simulink Of Hard Disk Read/Write Channel

With the data storage devices pervasive impacting in computing, communication, consumer, and entertainment systems, hard disk technology has been developing greatly to meet the high-performance external equipment. Recently, as the capacity of magnetic disk drive increases significantly, while the size of disk drive is keeping smaller and smaller, it is necessary to use advanced read/write channel system.The automatic gain control(AGC) system of high-performance analog front-end (AFE), dedicated to read/write channel of the hard disk, can amply normally the read head signal, compensate circuit gain, restrain the absolute amplitude of signal detected, retain the best resolving power of the relative amplitude in the spectrum and prevent channel saturation and data loss.The main technology included in achieving AGC system are the variable gain amplifier(VGA) design, the filter constant delay characteristics, the loop gain stability time, the linear characteristics of the system loop and so on. On the basis of hardware implementation, there are some discussions about the realization of the gain amplifier, the compare between standard exponential function and constructed exponential function. In addition, a in-depth study of the continuous time low-pass filter(CTF) group delay and experimental results under different conditions are given too.Under the conditions of highly storing density, AGC system model and MATLAB simulation can provide some important information and theoretical basis for experimental platform and existing read/write channel, while they do some modest contributions to the hard disk servo-burning technology.