Base-band digital signal generator is an essential device in Synthetic Aperture Radar （SAR）. It plays an important role in satisfying the development of multi-resolution and multi-mode of SAR system. With the digitization of SAR signal processing

base-band digital signal generator has substituted for SAW devices

and functioned as a part of the digital linear frequency modulator （chirp）

which generates various sending signals for the radar. Facing more and more complicated SAR systems

in the meanwhile

developers must deal with testing and validation problems of the system. So it’s necessary to develop a device that can help developers to validate the functions of SAR sub-assemblies

and digital signal generator just functions as a test device for the base-band signal processing devices of the radar. The author first introduces the functions of high-speed digital signal generator developed for SAR system

then analyses the principle and design process of linear frequency modulation signals

and discusses on the test function of the signal generator. The performance

composition and design scheme of a high-speed base-band digital signal generator is presented according to the above two functions.