METHOD AND SYSTEM FOR MEASURING A RELATIVE MAGNITUDE AND AN ABSOLUTE MAGNITUDE OF A SIGNAL READ OUT FROM A DATA RECORD MEDIUM

摘要

PURPOSE: An apparatus is provided to improve a characteristic of a magneto-resistive read/record head by measuring at a read channel a magnitude of a read signal acquired from a data record medium. CONSTITUTION: In a circuit for measuring a magnitude of a read signal, a gain correcting amplifier receives the read signal. A multiplexer has a control voltage signal output and a sense output coupled to the amplifier, and a sense voltage signal associated with a gain of the amplifier is generated from a detection output of the multiplexer. A digital-to-analog converter(DAC)(88) has an input and an output, and a control logic circuit(90) is coupled to the input of the DAC. The control logic circuit(90) transfers a digital word value indicating a control voltage signal to the DAC. A comparator(82) has a first input coupled to the output of the multiplexer, a second input coupled to the output of DAC and an output. The comparator(82) compares a sense voltage signal generated at the first input and a control voltage signal generated at the second input. The control logic circuit transfers the digital word value to the DAC until the control voltage signal substantially equals to the sensed voltage signal. A digital word associated with the control voltage signal substantially identical to the sensed voltage signal indicates a relative magnitude of the read signal.