Pulse-Enhanced High Speed Ferrite Head Write Driver
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
A pulse-enhanced driving technique is described which permits substantial writing speed improvement in a ferrite head write driver. Viewing from the write driver, a ferrite head is similar to the RLC circuit shown in Fig. 1. Although this is a simplified model, it reflects the writing speed limitation imposed by the head inductance (Image Omitted) and capacitance. When driving it with a current step from O to Iw the response can be described by where the dot means time derivative. A fundamental limitation of the rising speed of inductor current IL can be easily seen from these equations. Starting from zero state (IL = O, FC = O), the capacitor voltage cannot increase faster than Iw/C. Unfortunately, equation 1 indicates that the inductor current rising speed is proportional to this limited capacitor voltage.