Design And Implementation Of Zero Intermediate Frequency Receiver On Portable Software Radio Platform

Compared with the traditional receiver superheterodyne structure, new zero intermediate frequency receiver has many advantages, such as simple structure, low hardware cost, small size, low power consumption, ease of integration and so on. It fits the trend of wireless communication products. So it is very competitive. However, the architecture of zero intermediate frequency receiver has some problems. Especially, I/Q imbalance will worsen SNR and performance of receiver.This paper designs and implements the zero intermediate frequency digital receiver of portable software radio platform. Details are as follows:First of all, according to the requirments of portable software radio platform, paper designs and implements the hardware platform of receiver. The overall program of hardware is built, modules are divided and devices are selected. Then, thesis simply designs some modules, including digital receiver, digital processing and local oscillator. It also degsigns key interfaces. Paper designs RF reception channel and clock source in detail, calculates reception link and simulates clock phase noise. In addition, the signal ranges from 225 MHz to 512 MHz and the maximum bandwidth of signal is 2MHz.Secondly, in combination with the hardware of receiver, digital compensation algorithm solves I/Q imbalance. By means of program design and device selection, the consistency of I and Q circuits are improved. Besides, considering the limited hardware resources and valuable communication bands, program chooses a blind estimation compensation algorithm which only needs a small amount of calculation and takes up no band. Otherwise, paper introduces algorithm model and imbalance parameter estimation method. By analyzing simulation results, the image rejection of receiver can improve 29.4dB when amplitude imbalance parameter is 1 and phase imbalance parameter is 0.1 degrees.Finally, hardware platform and the effect of algorithm are tested and analyzed. According to testing RF receive path, local oscillator, ADC and clock module. we can know the effect of the hardware. Testing system receiver chain with the frequency ranging from 215 MHz to 512 MHz, before compensation, the image rejection of reception link are less than demand indicators, but after compensation, the image rejection of reception link are greater than 30 d B to meet the requirements of system.This paper designs and implements hardware circuits of zero intermediate frequency digital receiver. Digital compensation algorithm is used to solve I/Q imbalance Based on adequate test, the hardware meets the needs of design. After compensation, the image rejection meets the requirements. Paper has certain significances for designing hardware on portable software radio platform and compensating I/Q imbalance with algorithm.