| 摘要 |
PURPOSE:To remove a DC offset without an inductance, by comparing a DC level of output of each amplifier amplifying the output of a plurality of reproducing heads with a common reference voltage and uniforming the DC level of reproducing signals. CONSTITUTION:An output of a magnetic head 1a is applied to a differential amplifier 4a via an amplifier 3a. The collector potential Va of a transistor(TR) Q2 of the differential amplifier 4a is given to an LPF11a via a TRQ5 and the DC component only is picked up. The output of the LPF11a is compared with a common reference voltage Vr at a differential amplifier 12a, and the error output is fed back to a variable current source 10a. As a result, the DC potential Va of the collector of the TRQ2 is made equal to the reference voltage. Since the similar processing is performed also to a magnetic head 1b, the DC level of the reproducing signals obtained from TRs Q5, Q6 is made uniform. Thus, the DC offset can be rejected without using any inductance. |
