Digital-to-radio converter for software radio

We have proposed a digital-to-radio (D/R) converter that can directly change a digital signal generated by a logic circuit into a radio signal. This D/R converter enables an RF circuit and an antenna to be composed of one simple device, and the radio can be directly controlled by software; this is the essence of software radio. The proposed converter is therefore applicable to an adaptive array antenna system and an adaptive terminal. We developed a new algorithm that enables the D/R converter to convert digital signals directly to radio signals. Detailed analysis of a digital signal which is a square waveform makes it clear that the transmitting signal is directly generated by the logic circuit. We also developed a circuit design for a software radio transmitting unit that incorporates the D/R converter. The most critical point of this circuit design is high-precision phase adjustment. In order to precisely adjust the phase of the digital signal, we developed a new circuit which uses the delay gate of an LSI