Circuit for Reducing Preamp Transients of Magnetoresistive Read Head Elements
Original Publication Date: 1988-Feb-01
Included in the Prior Art Database: 2005-Feb-14
While using sector servo information, it is necessary to enable the read system immediately after writing the previous sector in order to read servo information before the beginning of the next sector. With a magnetoresistive (MR) head element, the turn-on of the read element causes a transient to occur in the preamp due to the change of DC level at the preamp inputs. This temporarily prevents the accurate reproduction of the readback signal, rendering it useless to the servo system. This circuit reduces the magnitude of the transient, thus allowing the readback signal to become useful to the servo system in a much shorter period of time. As shown in the figure, a pair of transistors, T3 and T4, are added to the preamp 10.