| 摘要 |
PURPOSE:To obtain the flat characteristics within a pass band and to simplify the constitution of a BPF by applying a signal of the center frequency to a saturated area of the input-output voltage and controlling the input voltage so that the high and low band cut-off frequencies are not applied to said saturated area. CONSTITUTION:For an active BPF9, the center frequency is set at f0 together with the cut-off frequencies of low and high bands set at f1 and f2 respectively. In case the input voltage of the BPF9 is higher than the output voltage Vs and it is in a saturated area, the signal input voltage of frequencies f1 and f2 is controlled to the voltage VIN2 to the signal of f0. This prevents that the signals of f1 and f2 reach the saturated area. Thus the flat frequency characteristics are obtained for a pass band having frequencies of f0 of the filter. This amplifies the constitution of a BPF. |
