Ad6620 If Digital Receiver System Design And Research

Software Define Radio[SDR] (or Software Radio[SR]) is one of communication technology which have vast foreground. Its essential idea is that establishing an all-purpose hardware and all functions are accomplished by software. It is received re-cognition for its opening and programmability. At present, SDF is a focus of military communication and personal mobile communication. Software Radio wants all functions are accomplished by software, so at first we must make our system become digital system. It means that ADC need near by the antenna, videlicet, we must realize IF digital or RF digital. We need to turn the frequency of IF signal or RF signal to the base band, and for the rate of output data of ADC is too high, we could not realize real-time signal processing by the all-purpose DSP. So digital down converting is one of the key technologies of software radio. It can improve the efficiency and reliability of communications. Furthermore it is important to realize absolute Software Radio. This paper focuses on the technologies in digital down converting, such as sampling theorem, sampling-rate conversion, digital filter and digital orthogonal demodulation. On the base of this, the paper analyzes application of digital down converting in the AD6620 which is a programmable down converter. After complete the design of the circuit and the hardware realization, introduce the testing method and the testing results and analyze these testing results.