PLL Reference Design Using a Quadband VCO

This demonstrates a novel PLL circuit design using ADI’s quadband VCOs comprised of four narrow bands integrated into a single package. This design delivers the benefits of the frequency range of wideband PLLs, with excellent phase noise performance and lock times of a narrowband PLL. An on-board active loop filter circuit has been designed for optimal phase noise performance across the four frequency bands of the quadband VCO. Control circuitry has been designed for fastest switching time between bands. A phase resync feature is also demonstrated for phase critical applications such as beamforming.