| 摘要 |
PURPOSE:To vary filter characteristics easily with simple constitution by using the 1st charge transfer element BBD, the 2nd BBD having a capacity element with capacity twice that of the capacity element of the 1st one, and the 1st and 2nd variable impedance elements. CONSTITUTION:The 1st BBD10 supplied with an input terminal at a terminal 1 and driven by clock signals phi1 and phi2 and the 2nd BBD22 equipped with an element C0'' with capacity twice that of the capacity element C0 of the 1st one are provided. The DC compnent of the input signal is supplied to the terminal 1'' of the BBD22, which is driven with the signals phi1 and phi2. Between difference delay elements of the BBD10, the series circuit of the 1st variable impedance Z active element Qx and a current inverting circuit 20 is connected. Between a delay output terminal 21 connected to the circuit 20 and the capacity C0'' of the BBD22, the 2nd variable Z active element Qy is connected and to a terminal 23 to which the bases of the elements Qx and Qy are connected in common, the signal phi1 and a variable control signal Vc are supplied being superposed. Then, varying the signal Vc varies filter characteristics easily. |
