The Optimal Design Of The Digital Tester For Frequency Response Characteristic

Sweep tester is used to measure the frequency response of circuit. It’s very important in research and design of the electronic products. At first, this thesis lists the advantages and disadvantages of the main sweep testers and makes an analysis of the structure and principle, at last an optimal design has been worked out.Here we choose STM32F217as our controller; STM32F217is a powerful controller with rich resources, high frequency up to120MHz, up to1Mbyte Flash memory, up to128+4Kbytes of SRAM. The sweep signal source is made of AD9854, it can provide excellent dynamic performance. The attenuator contains two parts. The first one implements-0.1dB step by modifying registers in AD9854. The-4dB step is composed by the π-type impedance network. The structure of the attenuator is simple and can easily been fixed on the board. We simplify the design of the input channel and improve the performance of the AD8302at low frequency.With the development of embedded technology, products can be divided into the framework and application. Here the framework includes the application programming interface of AD9854, AD8032and so on. We design a graphical interface base on uCGUI and talk about how to replant the μC/OS on STM32F217. At last we focus on the data process task, work out a method to solve the nonlinear measurement of AD8302.At present, we work out the digital frequency characteristics tester for20Hz to60MHz. It works well, and it is better than others in some respects.