Selecting a digital signal generator

摘要

Two basic architectures dominate the market for signal generators: the heterodyne architecture, where the modulation is applied to a fixed IF frequency while still in digital format and then upcon-verted, and the direct-at-RF modulation architecture where a wideband IQ modulator is employed. Both architec-tures have their ad-vantages and drawbacks, and each can achieve excellent performance matched to the desired application. The heterodyne architecture has the advantage of being able to create signals and multisignal environments across a wide instantaneous frequency band, but requires additional filtering to ensure that only the desired modulated RF signals are present at the output. The direct-at-RF modulation architecture simplifies the RF conversion segment but requires a wideband IQ modulator with high performance throughout the operating frequency range of the generator.