Upload
doandiep
View
214
Download
0
Embed Size (px)
Citation preview
Agenda
• Fundamental noise concepts
• What’s Noise Figure
• Noise figure Measurements
• Agilent Noise Figure Solutions – Demos
Page 2
• What’s Phase Noise
• Phase Noise Measurements
• Agilent Phase Noise Solutions - Demos
Agenda
• Fundamental noise concepts
• What’s Noise Figure
• Noise figure Measurements
• Agilent Noise Figure Solutions – Demos
Page 3
• What’s Phase Noise
• Phase Noise Measurements
• Agilent Phase Noise Solutions - Demos
Noise Can Obscure Weak Signals
Amplified Signal
(with added noise)
Small Signal
Page 4
Real (Imperfect) Amplifier
noise)
• Noise is always present in real system components
• The added noise limits the detection of weak signal s
• Noise floor is a crucial parameter for receivers
Inherent Noise-Producing Phenomena
• Thermal noise (Johnson noise)
• The kinetic energy of electrons and holes due to their finite temperature
Ptherm = kTB (watts)
Where k = Boltzmann’s constantT = temperature in KB = system’s noise bandwidth
Page 6
• Shot noise
• Due to quantized, random nature of current flow
• Uniform frequency spectrum (like thermal noise)
• Flicker noise (1/f or pink noise)
• A low-frequency phenomenon in which noise power has a 1/f spectral density
Noise Power at Standard Noise Temperature (290K)
RL - j XLR+jX
k = 1.38 x 10-23 joule/KT = Temperature (K)B = Bandwidth (Hz)
Noise Source
Page 7
Available noise power = P av = kTB
At 290K, P av = 4 x 10 -21 W/Hz = -174 dBm/Hz
(In deep space, kT = -198 dBm/Hz)
Agenda
• Fundamental noise concepts
• What’s Noise Figure
• Noise figure Measurements
• Agilent Noise Figure Solutions – Demos
Page 8
• What’s Phase Noise
• Phase Noise Measurements
• Agilent Phase Noise Solutions - Demos
What Is Noise Figure ? (A Practical Example)
Nin
Sin / Nin = 40 dB
Nout
Sout / Nout = 30 dBSin
Sin
Page 9
a) S/N at amplifier input b) S/N at amplifier output
B = 25 MHz
Nin
Gain = 20 dB
Nout Noise figure (NF) = Sin / Nin
Sout / Nout
= 40 dB – 30 dB = 10 dB
Definition of Noise Figure by Equation (Friis, 1944 )
Nin
Na
Rs
Ga
Nout = Na + Nin • Ga
N = kT B , where T = 290K
Page 10
Noise Figure = NF (dB) =10 logSin / Nin
Sout / Nout
= 10 logNa + Nin • Ga
Nin • Ga
Nin = kT0B , where T 0 = 290K
= 10 log (noise factor)
= 10 log F
FdB = Actual output noise(dBm) – Noise from “perfect” device(dBm).
What is the noise figure?
Z0 at 290K
30dB gain10 MHz bandwidth
No = –70dBmNo = –70dBm
Noise Figure = a) 24dB?b) 4dB?c) 25dB?d) 6dB?
Effective Input Noise Temperature (T e)
Out
put N
oise
Pow
er
Nin
Rs
Ga
Na
Nout
Page 12
Out
put N
oise
Pow
er
Na
Source Temperature (K)Te0-Te
Noise Temperaturean alternative to Noise Figure
ΣkToB
kT B
ideal network
Z0To;Z0 Te
kTeB
No = kT0BG + kTeBG= k(T0 + Te)BG
Cascade Formula
G1 G2
F2F1
F = F + F2-1
NF of a two -stage system =
Page 14
Where ΣΣΣΣ Fn is the cumulative NF up to the nth stage,and ΣΣΣΣ Fn+1 is the cumulative NF up to the (n+1)th stage
F12 = F1 + F2-1
G1NF of a two -stage system =
ΣΣΣΣ Fn+1 = ΣΣΣΣ Fn + Fn+1 - 1
ΣΣΣΣ GnNF of an n-stage system =
Importance of Knowing NF: Satellite Example
S/N = 4 dB
Transmitter:
ERPPath LossesRx Antenna GainPower to Rx
+55 dBm-200 dB+60 dB
-85 dBm
Receiver:
Noise @ 290K -174 dBm/Hz
Power to antenna: +40 dBmFrequency: 12 GHzAntenna gain: +15 dB
ERP = +55 dBm
Page 15
Noise @ 290KNoise in 100 MHz BWReceiver NFRx Sensitivity
-174 dBm/Hz+80 dB
+5 dB-89 dBm
Receiver NF: 5 dBBandwidth: 100 MHzAntenna Gain: +60 dB
• Choices to increase margin by 3 dB:
1. Double transmitter power2. Increase gain of antennas by 3 dB3. Lower the receiver NF by 3 dB
Agenda
• Fundamental noise concepts
• What’s Noise Figure
• Noise figure Measurements
• Agilent Noise Figure Solutions – Demos
Page 16
• What’s Phase Noise
• Phase Noise Measurements
• Agilent Phase Noise Solutions - Demos
Y-Factor (Hot/Cold) Method
Nin= kB (T h or Tc)
Rs
Ga
Na
Nout= Nh or N c
Out
put P
ower
Slope = kBGa
N
Nh
Page 17
Source Temp (K)
Na
-Te Tc Th
NcY = Nh / Nc
• Hot and cold noise sources are applied separately t o the DUT and the output power is measured
• The avalanche diode is a popular hot/cold noise sou rce
BiasInput
NoiseOutput
Matching Pad
Agilent Noise Sources
T - T
Page 18
Excess Noise Ratio = ENR (dB) = 10 logTh - Tc
T0
(T0 = 290K)
• A calibration report (ENR versus frequency) is prov ided with each source
• Broadband and capable of electronic switching betwe en Tc and T h
• Source match is improved with a built-in matching p ad
• The diode is designed for stability over time
Calibrating Out NF of Measurement System
DUTVariable
AttenuatorNoise
Source
F2
F1, G1
F12
Page 19
F12
F1 =F2 - 1
G1
F12 -By cascade equation:
• If F12 ≅F2 - 1
G1
, then uncertainty increases
• F12 (F of system) is measured with DUT connected
• F2 is measured by connecting source directly to analyze r
Y- Factor Method
NOISE SOURCE
DUT
PRECISION IFATTENUATOR
−
−−
−=
1
1290
1290
log10Y
TY
T
F
ch
Where Y = Change in IF attenuator to maintain reading on detector as source switched ON and OFF
KT
YENRF
C 290 if
)1log(10
=−−=
Beware High DUT NF!
If F is large, N a >> kTBG and Y ≅ 1
Y = Nc
Nh = Na + kThBG
Na + kTcBG
Therefore:
Page 21
The Y-factor method is not suitable for very high noise figures ( ≥ 30 dB)
Slope = kBG2
Slope = kBG1G2
The NFA Also Measures DUT Gain
Nh_mea
s
Nh_cal
NNh_meas – Nc_meas
Page 22
Source Temp (K)
Nc_meas
Nc_cal
ThTc
G1 =Nh_meas – Nc_meas
Nh_cal – Nc_cal
G1(dB) = 10 log G 1
Devices That Can Be Tested with Agilent NFAs and SA-Based Solutions
• Passive two-port devices
• Active two-port devices
• Mixers and receivers
Passive Mixer
Receiver
LO
IF
Page 23
AmplifierFET,
Transistor
Passive 2-Port
Mixer
LO
Agenda
• Fundamental noise concepts
• What’s Noise Figure
• Noise figure Measurements
• Agilent Noise Figure Solutions – Demos
Page 24
• What’s Phase Noise
• Phase Noise Measurements
• Agilent Phase Noise Solutions - Demos
Agilent Noise Figure Solutions Portfolio
MXA
PSA Series
Highest Performance Spectrum Analyzers
NFA Series
Only Dedicated Noise Figure Analyzers
PNA-X
Highest Performance Network Analyzer
Page 25
Pric
e
Performance
ESA Series
Economy Portable Spectrum Analyzers
EXA
Economy-Class Signal Analyzer
MXA
Super Mid-range Signal Analyzer
Agilent 346 Series Noise Sources
Source Temperature (K)
Out
put P
ower
(W)
Na
Tc Th
ENR ≅≅≅≅ 6 dB346A
Source Temperature (K)
Out
put P
ower
(W)
Tc Th
Na
ENR ≅≅≅≅ 15 dB346B/C
Page 26
Source Temperature (K) Source Temperature (K)
• 346A: 10 MHz to 18 GHz, nominal ENR of 6 dB
• 346B: 10 MHz to 18 GHz, nominal ENR of 15 dB
• 346C: 10 MHz to 26.5 GHz, nominal ENR of 15 dB
• Can be used with NFA Series, PSA, ESA-E with noise figure option, and MXA/EXA with N9069A noise figure application
• 346C K01: 1 GHz to 50 GHz, nominal ENR of 20 dB
Agilent SNS Series Noise Sources
• N4000A: 10 MHz to 18 GHz, nominal ENR of 6 dB
• N4001A: 10 MHz to 18 GHz, nominal ENR of 15 dB
• N4002A: 10 MHz to 26.5 GHz, nominal ENR of 15 dB
Page 27
NF_102 Noise Figure Basics
January 2008
• Can be used with NFA Series noise figure analyzers, ESA-E with noise figure option, and MXA/EXA with N9069A noise figure application
• ENR data is stored in EPROM and automatically downl oaded to analyzer
• Source temperature is monitored by a built-in therm istor for compensation
Agenda
• Fundamental noise concepts
• What’s Noise Figure
• Noise figure Measurements
• Agilent Noise Figure Solutions – Demos
Page 30
• What’s Phase Noise
• Phase Noise Measurements
• Agilent Phase Noise Solutions - Demos
Phase Noise
Practical sinusoids are never perfect!
t
v(t) = (V0 + ε(t)).cos(ωt + φ(t))
ε(t) = instantaneous amplitude fluctuations
φ(t) = instantaneous phase fluctuations
LONG-TERM FREQUENCY STABILITY
f
time
(days, months, years)
Slow change in average or
nominal frequency
SHORT-TERM FREQUENCY STABILITY
nominal frequency
time (seconds)
Instantaneous frequency variationsaround the nominal frequency
f
f o
TYPES OF SHORT TERM NOISE
REF 8.3 dBm ATTEN 28 dB
RES BW10 Hz
MKR 9.999 999 581 8 GHz
8.28 dBm
Deterministic (Discrete) - "Spurious"
Continuous (Random) - "Phase Noise"
SPAN 500 HzSWP 150 sec
CENTER 9.999 999 482 GHzRES BW 18 Hz VIEW 1 Hz
UNIT OF MEASURE
(f) - defined as single sideband power due to phase fluctuations referenced to the carrier frequency power:
In a 1 Hz bandwidth at a frequency f Hz from the carrier
Divided by the signal's total power
L
Usually phase noise is quantified as (f)L
Page 36
Divided by the signal's total power
(f) has units of dBc/Hz
(f) =Area 1 Hz bandwidth
Total area under the curve
FREQUENCY
AMPLITUDE
1 Hz
f 0 f 0 + fm
(f)
LOG A
LOG f
L
L
L
8684B EXT FM OFF, 8640B X7 REF, 320 KHZ PK DEV FM4 AVERAGES CARRIER FREQ = + 7.70DE + 09Hz [hp] APR 4 13:40 / 14:02
50
40
30
20
10
0
-10
-20
-30
Typical Phase Noise Plot
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-15010 100 1K 10K 100K 1M 10M
40MHz1
Hz
(f) [dBc/Hz] vs f [Hz]L
Carrier phase noise in a Doppler Radar
Txf
Reflected signal from building at f Hz.
clutter
Tx
RxReflected signal from car
at f+ ∆f Hz.
How local oscillator phase noisecan obscure the returned Doppler
signal from the moving object.
Agenda
• Fundamental noise concepts
• What’s Noise Figure
• Noise figure Measurements
• Agilent Noise Figure Solutions – Demos
Page 41
• What’s Phase Noise
• Phase Noise Measurements
• Agilent Phase Noise Solutions - Demos
Phase Detector Technique
Phase Detector
Low Freq. SpectrumAnalyzer displays
Sφ(fm)
Phase Detector
Unit Under Test
Reference(same freq. as
UUT)
Sφ(fm) =Spectral density of phase
fluctuations
Reference Source/PLL Measurement Technique
MICROWAVEDOWNCONVERTER
BASEBAND TEST SET
∆Vrms(f) = Kφ ∆φ rms(f) [V]
OSCILLATORUNDER-TEST
REFERENCESOURCE
PHASEDETECTOR
PHASE-LOCKLOOP
SIGNAL CONDITIONING
BASEBANDANALYSISHARDWARE
BASEBAND OUTPUTSIGNAL
TUNINGVOLTAGE
RF OUT
The Spectrum Analyzer Method
Unit Under Test
RF Spectrum Analyzer
Measure C/N at the required frequency offset.
• How to define Phase Noise on a spectrum
analyzer?
4 elements:
1) Carrier frequency
2) Offset freq. from carrier freq.
P0
dBc/Hz
The Spectrum Analyzer Method
2) Offset freq. from carrier freq.
3) Power spectral density (in 1 Hz BW)
4) Relative to carrier power in dBcf0 fm (offset freq.)
1 Hz BW
dBc/Hz @ offset freq. fm
Assuming AM noise << PN
8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz
OscillatorUnder-Test
The Spectrum Analyzer Method
- Easy to configure/use
– Measures total noise (phase noise + AM noise)
– Device drift limits close-to-carrier capability
– SA internal LO limits overall sensitivity
Agenda
• Fundamental noise concepts
• What’s Noise Figure
• Noise figure Measurements
• Agilent Noise Figure Solutions – Demos
Page 48
• What’s Phase Noise
• Phase Noise Measurements
• Agilent Phase Noise Solutions - Demos
• Direct Spectrum Analysis
Overview of Agilent PN Measurements solutions
• Carrier removal+ BB Analysis
ESA/Opt. 226
PSA/Opt. 226 E5052B
Signal Source Analyzer
• PN measurements made easy by a general-purpose SA w/ PN
personality• More focused measurements
• Dedicated to component tests
856X/85671A
E5505APN Measurement Solution
MXA/EXA with N9068A
Phase Noise: Measurements on X series
• Log Plot ; one button measurement to measure the phase noise in the desired frequency range..
• Spot Frequency ; one button measurement to measure the phase noise at certain offset in the time domain faster.
• Monitor Spectrum ; allows to watch the signal • Monitor Spectrum ; allows to watch the signal spectrum without exit from the Phase Noise mode. Subset of General Purpose SpecAna
• IQ Waveform ; general purpose IQ waveform measurement without exit from the Phase Noise mode.
Log Plot Measurement: Using Markers
� Up to 12 markers can be used in addition to the Decade Table.
� Integrated Phase Noise measurements like RMS Noise (in
Degree, Radian, Jitter) plus Residual Degree, Radian, Jitter) plus Residual FM can be measured using up to 12
Band Power markers
Log Plot: DANL Display and Cancellation
�Use DANL display to determine whether the measured phase noise is
from the DUT, or is due to the instrument DANL
�Improve measurement accuracy by using PN cancellation feature
Demo
Solution used for the demo: MXA N9020A + Phase Nois e applicationMXG vector signal generator
www.agilent.com/find/MXAwww.agilent.com/find/MXG