Filter with low output impedance - uses CCD filter between series amplifier networks controlled by CMOS clock

摘要

The filter uses the transfer of electric charge in a semiconductor formed on a multi-layered ceramic substrate. A charge coupled device (CCD) charge transfer filter is formed on an N-type silicon substrate with two grids. The device has positive balancing coefficients. Two bipolar amplifiers are included, each of which is associated with a network of resistors and capacitors formed in thin layers on the substrate. The amplifiers together with their associated networks each comprise second order analogue filters in series with the input and the output of the CCD filter. A CMOS clock controls the CCD filter. In an alternative arrangement the substrate may carry two such filters, the resistors and capacitors being formed on the same substrate. The clock however is formed on a separate substrate electrically connected to the first.