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48
Agilent E5505A User’s Guide
3
Phase Noise Basics
What is Phase Noise?
Frequency stability can be defined as the degree to which an oscillating source
produces the same frequency throughout a specified period of time. Every RF
and microwave source exhibits some amount of frequency instability. This
stability can be broken down into two components:
•
long-term stability
•
short-term stability
Long-term stability describes the frequency variations that occur over long
time periods, expressed in parts per million per hour, day, month, or year.
Short-term stability contains all elements causing frequency changes about the
nominal frequency of less than a few seconds duration. The chapter deals with
short-term stability.
Mathematically, an ideal sinewave can be described by
Where
= nominal amplitude,
= linearly growing phase component,
and
= nominal frequency
But an actual signal is better modeled by
Where
= amplitude fluctuations,
and
= randomly fluctuating phase term or phase noise.
This randomly fluctuating phase term could be observed on an ideal RF
analyzer (one which has no sideband noise of its own) as in
V t
( )
Vo
2
π
fot
sin
=
V o
Vo
2
π
fot
sin
fo
V t
( )
Vo
ε
t
( )
+
2
π
fot
∆φ
t
( )
+
sin
=
ε
t
( )
∆φ
t
( )
Содержание E1420B
Страница 24: ...24 Agilent E5505A User s Guide ...
Страница 46: ...46 Agilent E5505A User s Guide 2 Introduction and Measurement ...
Страница 128: ...128 Agilent E5505A User s Guide 5 Absolute Measurement Fundamentals ...
Страница 226: ...226 Agilent E5505A User s Guide 7 Residual Measurement Fundamentals ...
Страница 322: ...322 Agilent E5505A User s Guide 13 Baseband Noise Measurement Examples ...
Страница 340: ...340 Agilent E5505A User s Guide 14 Evaluating Your Measurement Results ...
Страница 358: ...358 Agilent E5505A User s Guide 15 Advanced Software Features ...
Страница 386: ...386 Agilent E5505A User s Guide 16 Reference Graphs and Tables ...
Страница 392: ...392 Agilent E5505A User s Guide 17 System Specifications ...
Страница 404: ...404 Agilent E5505A User s Guide 18 System Interconnections ...
Страница 452: ...452 Agilent E5505A User s Guide 20 PC Digitizer Performance Verification ...
Страница 466: ...466 Agilent E5505A User s Guide 21 Preventive Maintenance ...