JPS647303A - Readout circuit for magnetic disk device - Google Patents

Abstract

PURPOSE:To contrive to improve the slice level margin by providing a differentiation circuit and a waveform equalizing circuit exclusive for a gate generating circuit and using the exclusive use waveform equalizing circuit so as to slow down a waveform of a front part of a readout signal of a magnetic head from a peak point and to make the latter part steep thereby obtaining a gating differentiation waveform by the exclusive differentiation circuit. CONSTITUTION:The waveform equalization circuit 16 for a gate and the differentiation circuit 17 for a gate receive a waveform 43 at a part (d) of a delay line output inputted from a differential amplifier 35 and outputted through a delay line 36 at their differential amplifier 42. The input waveforms in the delay line 36 are synthesized at the same time and the result is given to an attenuator 37, the waveform 44 is obtained at a point (e) and given to the differential amplifier 42. The waveform being negative at its front part of the peak point of the waveform and positive at its latter part as shown in the waveform 44 at the point (e) is supplied to the differential amplifier 42, from which a waveform 45 whose front part is not steep in the front part but steep in the latter part is outputted at a point (f). In giving the waveform 45 at the point (f) to the differentiation circuit 17 for the gate, a gating differentiation waveform 46 is outputted at a point (g). The latter part of the waveform 43 at the point (d) is made steep, then the amplitude of the latter part is increased to offer ease of detection.