In many applications including radar, electronic warfare, SIGINT or communication systems, the modulation bandwidth requirements are constantly increasing. At the same time excellent signal fidelity is necessary and distortions have to be kept at a minimum. Traditional signal generators can provide the required signal purity, but most of them offer modulation bandwidths of only about 100 MHz. External arbitrary waveform generators and IQ modulators can achieve a much larger bandwidth, but the downside to their use is carrier feed-through and images. By using software up-conversion or using digital I/Q modulation inside the arbitrary waveform generator (AWG) you can get bandwidth and signal purity.