| 摘要 |
PURPOSE: To prevent the lowering of a frequency of a reproducing amplifier by connecting a head reading out a recording signal to an emitter side of a transistor, connecting an inductance and a load resistor of a base grounded amplifier to the collector side and processing a signal. CONSTITUTION: The reproducing amplifier 10 for an MR head is constituted of the MR head 2, the transistor 3, a bias current source 4, the load resistor 5, a coil 11, a capacitor 6 for compensating a phase of a feedback loop and a current amplifier 7. The coil 11 is connected to the load resistor 4 in series. In such a case, when the resistance value of the head 2 is defined R1 , the value of the resistor 5 is R2 , the small signal resistance value of the transistor 3 is r0 , a wiring inductance is L1 and the inductance of the coil 11 is L2 , L2 = L1 (R2 /(R1 +r0 )). That is, the wiring inductance L1 occurring between the head 2 and the transistor 3 is canceled by the inductance L2 of the coil 11, and a high band gain Av =(R2 +ωL2 )/(R1 +r0 +ωL1 ) is held.
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