Structures and Methods for Automated Tuning in Wide Range Multi-Band VCO with Internal Reset Concept

摘要

Circuits and methods for automated real-time tuning of wide range frequency/delay voltage controlled oscillators (VCO) using a reset mechanism, to account for run-time variations such as power supply, temperature, reference clock frequency and input slew drift etc is described. It finds extensive applications in wide range, multi frequency band phase and delay locked loops. In one embodiment, an automated Jump-Down band switching structure and method for use in VCOs with a plurality of frequency bands is described. This involves monitoring the VCO's analog control voltage signal until it reaches a predetermined lower limit, at which time band switching to an overlapping lower frequency band is triggered by an internally generated reset signal, while simultaneously charging the analog control voltage to a limit in a pre-determined range of the lower band, to avoid phase detector malfunctions in the PLL/DLL system at lower control voltages during band switch.