A bipolar phase-locked loop system with programmable speed power characteristic

Abstract

An all bipolar phase-locked loop system is presented. The maximum operating frequency of the system can be traded off for reduced power dissipation using a single external resistor. The system contains a voltage controlled oscillator (VCO), two digital phase comparators, and a digital divider chain. The circuit uses analogue compatible I2L technology. The VCO uses a novel switching technique to improve the speed/ power performance. The circuit operates from a single supply voltage of a to 15 V. Initial measurements demonstrated operation of the system at maximum VCO frequencies from 1 kHz to 1 MHz with corresponding power dissipations of 150 μW to 50 mW respectively. Some improvement in the upper frequency limit is predicted for the final integrated version.