Skip to main content
Article
Fabricate a 2.4-GHz fractional-N synthesizer
Microwaves & RF (2013)
  • H Ameri
  • Mahmoud Moghavvemi, University of Malaya
  • a Attaran
Abstract

Fractional-N frequency synthesizers offer numerous advantages in terms of performance compared

to integer-N frequency synthesizers for emerging wireless communications applications.

Frequency synthesizers are used throughout communications systems for tuning the signal

frequencies needed for receiving and transmitting. As silicon CMOS technology has been applied at

higher frequencies, it has helped the expansion of wireless technology to a wide range of

applications.1,2 In particular, these synthesizers have supported applications requiring tuning with

fine resolution—from kHz steps to a few MHz—and low phase noise, on the order of -100 dBc/Hz

offset 10 kHz from the carrier.

Many of these synthesizers have been developed as integrated-circuit (IC) solutions.3 In terms of

circuit architectures, integer-N frequency synthesizers are often challenged in meeting performance

requirements such as loop bandwidth, phase noise, and channel spacing due to the fundamental

design of the integer-N divider modulus.

In contrast, a fractional-N frequency synthesizer can provide the loop bandwidths needed for many

of these emerging wireless applications, with fine channel spacing. In addition, they can achieve low

phase noise without excessive reference spurious levels. Since a fractional-N frequency synthesizer

uses a higher phase/frequency-detector (PFD) comparison frequency and lower division ratio than

an integer-N frequency synthesizer, low-frequency phase noise can be suppressed to a high degree in

a fractional-N synthesizer.5

Keywords
  • Frequency Synthesizer
Publication Date
Summer June, 2013
Citation Information
H Ameri, Mahmoud Moghavvemi and a Attaran. "Fabricate a 2.4-GHz fractional-N synthesizer" Microwaves & RF Vol. 52 Iss. 6 (2013)
Available at: http://works.bepress.com/mahmoud_moghavvemi/147/