Design Of Sweep Generator Based On DDS Technology

Frequency sweep generator is short for frequency characteristic test instrument. In thesignal processing process, often to the impedance and transmission characteristics of thenetwork signal to be measured and analyzed, while the frequency sweep meter is which hasthe function of the instrument. It provides convenient conditions for the frequencycharacteristics of the circuit to test, research, analysis, therefore, the study of frequency sweepmeter has important practical value and academic significance. In this paper, I put forward thedesign scheme of frequency sweep generator based on DDS technology, this paper adoptedthe modularized design concept, and each function module is respectively carried out thescheme argumentation and analysis. System mainly consists of five functional modules,which are: sweep signal generator module design, signal disposal circuit module design, theamplitude and phase detection circuit module design, main control circuit and the design ofman-machine interface circuit module. Sweep signal source circuit has adopted the mostpopular DDS technology, AD9854is a high level of integration of direct digital frequencysynthesis; the signal disposal circuit include the filter circuit; the power amplifier circuit andthe attenuator circuit design; the amplitude and phase detection circuit module usingamplitude and phase detector chip AD8302,which is produced American ADI company;main control circuit use the Luminary Micro (lumens nutria) company design LM3S811single-chip microcomputer, which based on ARM7core, microcomputer mainly used toanalyze and process data; man-machine interface circuit including keyboard control and LCDdisplay circuit, the keyboard control circuit control the input value of the frequency sweepsignal generator, LCD circuit will be processed in the frequency characteristic curves(including the amplitude-frequency curves and phase frequency curve) graphically displayintuitive. In this paper, design of frequency sweep meter has simple structure, stableperformance, the system friendly interface, basically achieved the purpose of this design.Therealization of the software programming under the environment of KEIL, software design usethe modular design thought, a module can be shared by multiple programs.