In these days, wireless communications are rapidly expanding worldwide and each person has a cellular phone. Several other wireless systems such Wireless LAN, Bluetooth, one-segment broadcasting, and GPS functions cab be integrated in a one terminal. However, these integration will have a limitation in the near future. So, software-defined radio (SDR) technology is proposed to overcome the limitation. Downloading application programs, an SDR terminal can work in different wireless systems. We are studying on integrated circuits suitable for implementing SDRs.