Patent ID: 6442271
Filing Date: 2002-08-27
Classification: H04L,H04M,Y02D

Abstract:
An isolation system having a master isolation circuit on a first side of an isolation barrier and an isolated circuit on a second side of the barrier, whereby signals are transmitted across the isolation barrier, comprising:a voltage controlled oscillator (VCO) located in the master isolation circuit, the VCO having input that is normally connected to receive an input voltage from a loop filter in a phase locked loop circuit; a bias voltage generator that produces a selected bias voltage; a multiplexer having inputs connected to the loop filter and to the bias voltage generator and an output connected to the VCO input; whereby during normal operation the loop filter is connected to the VCO input, and during a low-power mode of operation the bias voltage generator is connected to the VCO input so that a VCO output is provided even during the low-power operation.