PLL Synthesizers & VCOs

Linear Technology’s new ultralow noise integer-N and fractional-N phase locked loop (PLL) synthesizers provide world-class phase noise and the industry’s lowest spurious performance. The LTC6946 and LTC6948 reduce overall system cost, design complexity and solution size by integrating a high performance 6GHz-plus low phase noise VCO along with an ultralow noise charge pump, reference divider and phase-frequency detector. These devices are the PLL of choice in solutions requiring ultra-short frequency settling times thanks to the fast on-chip VCO calibration algorithm. The LTC6945 and LTC6947 separate the exceptionally low 1/f noise corner PLL core for use with an external VCO up to 6GHz.

While the LTC6945 and LTC6946 are integer-N PLLs, the LTC6947 and LTC6948 incorporate an advanced fourth order delta-sigma modulator to function as fractional-N PLLs. This modulator employs intelligent noise-shaping techniques to minimize noise contribution without creating fractionalization spurs found in most fractional-N PLLs on the market. All parts offer a programmable 1:6 output divider to provide a wide operating frequency range.

Linear Technology offers free and easy to use CAD tools to quickly and accurately simulate PLL synthesizer performance to ensure optimal and efficient design. PLLWizardTM is used in conjunction with the integer-N PLLs, and FracNWizardTM is for use with the fractional-N PLLs. These tools offer advanced PLL synthesizer design and simulation capabilities. You may use them to design noise-optimized loop filters, simulate loop frequency response and stability, simulate VCO and reference source noise contributions, and simulate output noise characteristics and statistics. Click here to download PLLWizard and FracNWizard

Technical Support