| 摘要 |
PURPOSE:To secure accurate characteristics with no effect of other inductions by using three resistances, two capacitors and an amplifier having its gain A set as 0<A<1 to constitute a band limiting circuit which suppresses high band saturation of a sound recording medium. CONSTITUTION:A band limiting circuit 13 consists of the 1st resistance R1 and a CR filter circuit 13A. The circuit 13A contains the 2nd and 3rd resistances R2 and R3 (R3=R0/n satisfied with R2=nR0), the 1st and 2nd capacitors C1 and C2 and an amplifier 76 having its gain A set as 0<4<1. The transmission function of the circuit 13A is set as T(S)=(1+S/Qb+S<2>)/(1+S/Qa+S<2>) as long as the center frequency is normalized at 1 together with Qa=n/[2+n<2>(1-A)] and Qb=n/2. Thus the frequency characteristics having a comparatively narrow width with the prescribed depth can be secured since the Qa can be set independently.
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