Design and Realization of Digital Frequency Characteristic Tester Based on DSP+FPGA

Adopting the DSP+FPGA signal processing framework and the principle of zero-IF quadrature demodulation, this paper designs and realizes a digital frequency characteristic tester with high accuracy, which can realize dot and sweep measurement for two port network, with frequency range between 100kHz and 50MHz, amplitude accuracy less than 1dB, and phase accuracy less than 1 degree. It can also display in real time on LCD both the amplitude-frequency characteristic curve and phase-frequency characteristic curve, with the scales of voltage gain, phase shift and frequency indicated on the screen.