Eder EIRAS Noise Seminar Signal Analysis Specialist · • The kinetic energy of electrons and...

Noise Seminar

Eder EIRAS

Signal Analysis Specialist

Agilent Technologies

Agenda

• Fundamental noise concepts

• What’s Noise Figure

• Noise figure Measurements

• Agilent Noise Figure Solutions – Demos

• What’s Phase Noise

• Phase Noise Measurements

• Agilent Phase Noise Solutions - Demos

Noise Can Obscure Weak Signals

Amplified Signal

(with added noise)

Small Signal

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

V+

Sources of Noise

Power Supply Noise

EMI Noise

Receiver

Device Noise

Phase Noise

LO

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

• 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

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








What Is Noise Figure ? (A Practical Example)

Nin

Sin / Nin = 40 dB

Nout

Sout / Nout = 30 dBSin

Sin

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

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

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 =

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

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








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

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

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

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:

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

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

AmplifierFET,

Transistor

Passive 2-Port

Mixer

LO

Agenda








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

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

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

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

Demo

Solution used for the demo: MXA N9020A + Noise Figu re application

www.agilent.com/find/MXA

MXG Additive AWGN Impairments

Agenda








Phase Noise

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

Concept of Phase Noise

f0f0

Ideal Signal Real Life Signal

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

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.

LO phase noise improvement

Doppler signal unresolved

Doppler signal resolved

Noise in Digital Radio

Phase Noise

Amplitude Noise

Agenda








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


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


- 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








• 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

MXG Additive Phase Noise Impairments

Eder EIRAS Noise Seminar Signal Analysis Specialist · • The kinetic energy of electrons and...

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Transcript of Eder EIRAS Noise Seminar Signal Analysis Specialist · • The kinetic energy of electrons and...