Improvement of Characteristics of Filters For Signal Process

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We have done the following two subjects in this joint research.1. Reduction of the chip area in the MOSFET-C filtersThe reduction of the chip area in integrated circuits is one of the most important matters to realize small size equipments which are used in portable electronic machines. In the research, we proposed a method of reducing the chip area of MOSFET-C filters which have a highly linear characterstic and are integrable in monolithic integrated circuits. Considering the current and voltage relations of MOSFETs in the circuit, some MOSFETs can be represented with the same relations and be deleted, thus we can reduce the number of MOSFETs leading to a reduction of the chip area. This results have been published in the Technical Report of Electronic Circuits of IEE of Japan.2. Low voltage high frequency current mode active filtersIn the era of small size and light weigh equipments, low voltege operation of circuits is quite important. In order to reduce the power supply voltage, we in this research proposed a current mode signal processing scheme. Using the diode connenctecd bipolar transisters and current mirrors, we can realize current mode signal processing circuits. Adding integrated capacitors to the current mode circuit, we can obtain current mode active filters. The filters are integrable in a monolithic form and have quite good characteristics, especially in high frequencyies. The results will be submitted to a journal.During this joint research, we visited Korea twice to discuss the results with professor D.Y.Kim and exchanged fruitfull opinion each other.