Read/write characteristics and noise properties of a thin film VCR head

The read/write characteristics and noise properties of the Embedded Thin Film (ETF) head, in which the size of the magnetic core is minimized by using a thin film coil are investigated and compared with those of a Metal in Gap (MIG) head. The small core size results in a smaller increase of impedance noise and it is clearly indicated that reducing the impedance noise is important in improving the Signal-to-Noise Ratio (SNR) over a wide frequency range, because the impedance noise has a greater effect over 30 MHz. In the writing process, a ghost pattern is found to be recorded by a fringing field from the spacer of the multiple-layered magnetic core, which results in a broadening of the isolated pulse. In spite of the ghost, however, the recording properties at a high frequency are not degraded, probably because the influence of the fringing field is small at a high frequency. As a result, the SNR of the ETF head is improved by 2.7 dB over the range of 1-40 MHz compared with that of the MIG head.