NOVEL REALIZATION OF UNIT ELEMENT WAVE SWITCHED CAPACITOR FILTER

In this paper some novel adaptor circuits are proposed to realize the unit element wave switched eapacitor filters driven by two phase clock signals. These circuits are very insensitive to the bottom plate parasitic capacitanees. To realize an adaptor only one unit-gain buffer is needed. The effects of top plate parasitie capacitanees and switch parasitic capacitanees on the adaptor are analyzed. The results show that the effects of the parasitics are small and can be reduced further by changing only one of the capacitances. These circuits are adaptable for realizing programmable filters and very useful to the PLC real-time speech synthesis. As an example, a 5th order unit element low-pass filter is given. The experimental results are in good agreement with the theoretical ones.