Apparatus and Method for Obtaining Desired Phase Locked Loop Duty Cycle without Pre-Scaler

摘要

An apparatus and method for obtaining a desired phase locked loop (PLL) duty cycle without a pre-scaler are provided. The PLL circuit of the illustrative embodiments utilizes two separate loops that simultaneously operate on the VCO. One loop ensures the frequency and phase lock while the other loop ensures the duty cycle lock. The VCO is modified to have an additional control port to adjust the duty cycle. Thus, the VCO has one control port for performing frequency adjustment and one control port for duty cycle adjustment. As a result, both the duty cycle and the frequency may be controlled using the VCO of the PLL circuit of the illustrative embodiments so as to achieve any desired duty cycle output without requiring a VCO pre-scaler circuit or duty cycle correction circuit.