| 摘要 |
PURPOSE:To improve problems such as return distortion by integrally forming a charge transfer type transversal filter and compatible switched capacitor filter on the same substrate. CONSTITUTION:Pre-filter 28 is composed of parallel-in/serial-out type charge transfer element CTD, and main filter 29 is of serial-in/parallel-out type CTD to constitute CTD filter 100. This filter 100 is integrally formed on the same chip as pre- filter 101 using a switched capacitor composed of MDSFET switches 82 and 83 and capacitors Cs and C. In this constitution, adequate selection of a frequency where switches 82 and 83 are switched and ratio Cs/C of capacitors removes a passing band generated an odd number greater than a sampling frequency and that an even number greater, thereby improving greatly problems such as return distortion. |
