Design and performance of an inductive current probe for integration into the trace suspension assembly

A low-cost, inductive current probe designed for integration into a disk drive trace suspension assembly is described. The main consideration for this design was to use the same materials currently found in trace suspension assemblies, and thus reducing costs, while at the same time providing a drive characterization tool capable of measuring 100 ps head field rise times. The inductive current probe consists of a pair of differential copper conductors fabricated adjacent to the write driver interconnects and magnetically coupled via a Ni-Fe thin film placed on top of these conductors. The differential conductor pair is connected to a high-speed sampling oscilloscope to measure the speed of the write current pulse and thus infer the write head field rise time. Data are shown for high-speed pulses generated with rise times of less than 100 ps.