| 摘要 |
PURPOSE:To constitute the parallel tuning circuit of LC constitution filter by an SWC circuit, by making the integration coefficient less than a prescribed value, in an inductance circuit consisting of a switched capacitor SWC integrator and a delay circuit. CONSTITUTION:An SWC integrator consists of an operational amplifier having an SWC capacitor C0 at the input and an integration capacitor Ca at the feedback circuit, and to said integrator an one sample time delay circuit consisting of an SWCC1 is in cascade connection to form the inductance circuit of SWC constitution by feeding back a signal to input terminals A,A' from the output terminal of the SWC integrator and the delay circuit via the SWC circuit. The L1 of a parallel resonant circuit consisting of the inductance L1 and a capacitor Cbeta is replaced with the inductance L1 of the SWC constitution, and the resonant circuit N including the capacitor Cbeta in the SWC is obtained by selecting the values of C0,Ca so that the integration coefficient C0/Ca is >=4. The SWC filter with broad dynamic range can be obtained by constituting the filter with this circuit N. |
