Linear Integrated Circuits

7

Phase-locked Loop and Its Applications

Objectives

To understand the concepts and working principles of the following:

• Phase-locked loop (PLL) with its architecture
  • (a) Operation of PLL
  • (b) Functions of various blocks in PLL
• Frequency synthesizer working to generate signals at one or more desired frequencies.
• Operation of analog frequency multiplier.
• AM, FM and FSK modulation and detection.

7.1 INTRODUCTION

The concept of phase locking of signals was introduced for communication circuits in the early years of 1930s. The French engineer De Bellescize first used the concept of phase-locked loop (PLL) in coherent communication circuits. Later, Signetics Company introduced Complete PLL in 1969 in the form of linear integrated circuit (IC) NE565. ...