Rf Digital Receiver

Along with the development of electronic technology, Modern electronic system works in the foul environments from bad to worse. This make more demands of electronic receiver accordingly. Conventional analog receiver can't adapt to this transformation perfectly, because of its inherence disadvantages. But, digital technology show powerful performance with it's reliability, flexibility, and anti-jamming. Analog receiver develops to digital technology gradually. The concept of software radio has been put forward in the international world after 1990's. Software radio unifies various standards, protocols and application systems into an open and universal hardware platform. It achieves intercommunication via different software. Software radio is a solution to compatible problems between different systems and standards of present electronic facilities. It's a significant milestone in development of electronics and communications technology. An important idea of software radio is to put the A/D module approach antenna as close as possible. So, the effect of analog process is reduced by RF signal digitalized soon. Considering the limit of modern electronic elements, it's hard to adopt structure with RF low-pass sampling. This paper introduces a wide band digital receiver based on under-sampling technique, and expatiates on correlative theories and computer simulations. Mean while, we discuss some key techniques and methods improving performance of receiver. At last, we strut a digital receiver, and the following test prove it achieve design target. I/Q mismatch affect receiver's performance greatly, it generated generally due to diversified factors. This paper proposes a digital calibration method to wideband receiver. First, the I/Q mismatch errors are estimated by local test signal injection. Second, a set of digital filters is constructed to calibrate them. The simulation demonstrates the effect of this method.