| 摘要 |
PURPOSE:To raise the frequency characteristic from the low frequency band of the LPF to the cut-off frequency band, by giving the impedance of a prescribed relation to one FDNR circuit at least and by adding one parallel resistance at least. CONSTITUTION:The FDNR system LPF is constituted with resistances, capacitors, and FDNR circuits. One FNDR circuit D10' is constituted with two operational amplifiers 1 and 2, impedances Z1-Z5, and resistance R6 connected between inversion input terminals of amplifiers 1 and 2 and the earth. Input impedance Zin of circuit D10' has relation 1/(S<2>A+SB) (S is a complex variable and A and B are real numbers), and attenuation near the cut-off frequency is small sufficiently to raise the frequency characteristic near it. Attenuation near the cut-off frequency is obtained sufficiently by inserting resistance R6, and the frequency characterisitic from the low frequency band to the frequency near the cut-off frequency is raisd gradually by inserting resistance 13 to a parallel circuit, and the output distortion for passage of overshoot pulses is reduced. |
