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A Method For Improving Analog / Digital FM modulation Transmitted Signal Quality By Using Controlled Escort Phase Locked Loop (PLL) and Dual Port Modulation

IP.com Disclosure Number: IPCOM000022256D
Original Publication Date: 2004-Mar-03
Included in the Prior Art Database: 2004-Mar-03
Document File: 2 page(s) / 36K

Publishing Venue

Motorola

Related People

Moshe Ben-Ayun: AUTHOR [+4]

Abstract

A circuit for improving phase error performance in a PLL.

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A Method For Improving Analog / Digital FM modulation Transmitted Signal Quality By Using Controlled Escort Phase Locked Loop (PLL) and Dual Port Modulation

Moshe Ben-Ayun, Mark Rozental, Haim Friedlander, Nir Corse

Abstract

A circuit for improving phase error performance in a PLL.

 

Description

It is important that the delays in the low port and high port paths are compensated so that they combine in phase and minimize distortion in the modulated FM signal. Amplitude mismatch can cause phase distortion to the modulated signal.

Delay Mismatch à degrades phase error performance if |delay| > symbols time.

Amplitude mismatch à degrades phase error.

The phase error can be improved by using ESCORT PLL configuration. Controlling the main Voltage Controlled Oscillator (VCO) setting for a limited frequency band, while changing the ESCORT NUD in order to synthesize the desired TX frequency. Limiting the main VCO frequency band will improve the VCO sensitivity changes, which will improve the dual port mismatch. Improving dual port mismatch will lead to an improvement in the phase error over the frequency band.

Block Diagram

Advantages

1. Enables improved phase error performance.

2. Enables multi modulation applications without the need in extra HW.

3. Enables the use of simpler TX VCO design.

Applications

C4FM systems,

Multi Modulations Applications


Document headers and footers

( Motorola, Inc. 2004 1