Synthesizers Meld Several Approaches

摘要

Addressing demanding frequency-synthesizer requirements often call for some design flexibility. The basic phase-lock-loop (PLL) frequency synthesizer provides reasonable spectral purity and frequency agility at low cost, in a space-efficient, low-power package, and has been at the heart of radio-frequency (RF) systems for some time. However, in cases requiring fast switching speed or low levels of phase noise or spurious signals, the use of a more complex architecture may be necessary. With an appropriate design approach, the use of a modern, low-cost, highly integrated PLL and direct-digital synthesizer (DDS) integrated circuit (IC) in combination can greatly facilitate the implementation of high-performance architectures.