Improvement of Characteristics of Filters For Signal Process

本次联合研究主要完成了以下两个课题： 1． MOSFET-C滤波器中芯片面积的减小集成电路中芯片面积的减小是实现便携式电子机器中使用的小尺寸设备的最重要的问题之一。在研究中，我们提出了一种减少MOSFET-C滤波器芯片面积的方法，该滤波器具有高线性特性并且可集成在单片集成电路中。考虑到电路中MOSFET的电流和电压关系，可以将一些MOSFET用相同的关系表示并删除，这样就可以减少MOSFET的数量，从而缩小芯片面积。该成果已发表在日本IEE的《电子电路技术报告》上。 2．低压高频电流型有源滤波器在设备体积小、重量轻的时代，电路的低电压工作非常重要。为了降低电源电压，我们在本研究中提出了一种电流模式信号处理方案。利用二极管连接的双极型晶体管和电流镜，可以实现电流型信号处理电路。在电流型电路中加入集成电容，就可以得到电流型有源滤波器。这些滤波器可以单片形式集成，并且具有相当好的特性，尤其是在高频下。研究结果将提交给期刊。在这项联合研究期间，我们两次访问韩国，与D.Y.Kim教授讨论研究结果，并交换了富有成效的意见。

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.