An ultra-wide band orthogonal digital signal generator

Three methods of generating waveform digitally are introduced. The time-domain and frequency-domain representations of a sine wave at the output of a waveform generator are carried out. Then some special problems and the solutions associated with ultra-high speed system design are given. An ultra-wideband orthogonal signal generator, whose sampling rate can reach 250 MSPS, is described. The system employs a data multiplexing architecture to decrease the speed of the memories. Test results show that the waveform generator has an excellent performance. The phase balance between two branches being less than 5 degrees, the SFDR being larger than 70 dBc, phase noise being lower than -100 dBc/Hz at 1 kHz offset can be reached when sine wave is generated.