Research On Wideband Linear-FM Chirp Waveform Generator At Ku-Band

The wideband linear-FM chirp waveform generator which has larger time-width and frequency-width has good range and radial velocity resolution. It is widely used in electronic measurement equipment, mobile communication system, linear frequency modulation radar, electronic station, navigation system and other fields. Generally baseband signal is generated by DDS chip and is extended to the work bandwidth. The baseband signal is moved to the work frequency band by mixer or frequency multiplier. By above methods spurious signal would be output and spectral purity of waveform generator is affected. Since many switches, filters and amplifiers are used in waveform generator, the waveform generator has large size and expensive cost. In this paper design is proposed to ensure the quality of wideband linear-FM chirp signal by improving frequency and bandwidth of the baseband signal, reducing the mixer, and avoiding to use frequency multiplier.This paper first introduces the basic principle of linear FM signal. Secondly According to engineering application, wideband high performance and complex frequency modulation signal is obtained by using FPGA+DA to generate high frequency baseband signal and using PLL to generate agile signal. The waveform generator size and performance are considered with the method of paper, and the waveform generator is fabricated and tested.Finally, the test results in the time domain and frequency domain clear prove the design feasibility and advantage of the method.