Institute of Research and Journals (IRAJ)
Phase Locked Loops (PLLs) are common applications for VCOs based frequency synthesizer is usually used in RF transceivers. There are three types of PLL, namely, an analog PLL, digital PLL and all-digital PLL. A given PLL can be implemented in various different architectures. PLLs can be used for clock generations, such as in a microprocessor, clock and data recovery, such as in an optical transmission system, or frequency synthesis, such as in a wireless radio. The general characteristic for VCOs used in PLLs is wide tuning range so that the entire frequency range is covered.