Write-current equalization for high-speed digital magnetic recording

In order to attain a high data transfer rate in digital magnetic recording devices, a new write-current equalization technique has been developed. This technique more than doubles the write-current transition speed so that it realizes high-speed write channels. The essentials of this technique are to tune the damping coefficient of parallel resonance at the head-to-write amplifier interface in an under-damped range and to eliminate over-shoot due to under-damped resonance with a simple write-current source operation. Improvements obtained with this method are an over-write noise reduction owing to the high-speed write current transition, and during read, a higher signal-to-noise ratio due to the increased number of turns around the head core. The signal-to-noise ratio was improved by nearly 6dB by the use of this technique on a read/write channel with a data transfer rate corresponding to 6MB/s.