**Analog
Design
**

**Kevin
Aylward B.Sc.
**

**Phase Noise**

__Overview
__

These
tutorials are designed to explain phase noise in a way that best allows for
design of real low phase noise oscillator systems. There is much confusion in
phase noise. For example, a key issue in phase noise analysis of oscillators is,
what causes up-conversion of low frequency 1/f noise to noise around the
carrier?

__Introduction
__

To
correctly understand phase noise, an understanding of where understanding went
wrong is surely useful. Repeating past mistakes is not usually a good strategy.

A
relatively well known noise analysis approach was introduced by Hajimiri-Lee
“A General theory Of Phase Noise In Oscillators” based on a Linear Time
Variant (LTV) model. However,
various aspects of this approach has been definitively shown to be seriously in
error, e.g. by A. Demir - “On the
Validity of Orthogonally Decomposed Perturbations in Phase Noise Analysis”.
Several authors also acknowledge this, however, there appears to be some level
of politically correctness that prevents them making clear statements as the
worth of that approach. For example:

The actual abstract of the HL paper *emphasis and
states:*

“…In particular, it explains the details of how
1/f noise in a device up-converts into close-in-phase noise and identifies methods
to suppress this up-conversion…”

However,
Hegazi, Real, Abidi – “The Designers Guide
To High Purity Oscillators” book state:

“…[HL]
does not formally address flicker noise at all. The treatment of flicker noise
in the original paper is performed without clear analysis or conclusive
answers…”

The
problem with all this politeness is that it does not really hit the nail on the
head. The HL paper, gives an erroneous understanding to the cause of
up-converted 1/f noise, and erroneous methods with which to design low
up-converted phase noise oscillators. These erroneous ideas then, unfortunately,
persist into the minds of real analog ic designers.

A
summary may be said to be:

**"The **** Hajimiri-Lee
****method can be shown to be valid for spherical chickens in a vacuum."
**

**"روش لي ال تي وي حاجي ميري، ميتواند بيانگر معتبر بودن جوجه كروي در خلا' باشد
"**

__Tutorials
__

Basic Phase
Noise Tutorial General phase noise overview

Basic
Phase Noise In Oscillators General
phase noise in oscillators overview

Invalidity of The LTV Model Proof that the Linear Time Variance theory is, essentially, useless for analyzing real circuits.

Invalidity Of Orthogonal Perturbation Demonstration that phase disturbance persists in real circuits when an impulse is instigated at the peak of the voltage waveform

Flicker Noise Nullification Demonstration of true, complete nullification of 1/f flicker noise down to 1Hz offset from a 500 MHz oscillator.

__Design
Ideas__

Lower 1/f Phase Noise Differential Oscillator

__References
__

Lee-Hajimiri-PN.pdf
- A General Theory Of Phase Noise In Oscillators

A-Demir.pdf
- On the Validity of Orthogonally
Decomposed Perturbations in Phase Noise Analysis**
**

© Kevin Aylward 2013

All rights reserved

The information on the page may be
reproduced

providing that this source is
acknowledged.

Website last modified 30^{th}
August 2013