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Eder EIRAS Noise Seminar 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 Page 2 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 Page 3 Noise Can Obscure Weak Signals Amplified Signal (with added noise) Small Signal Real (Imperfect) Amplifier • Noise is always present in real system components • The added noise limits the detection of weak signals • Noise floor is a crucial parameter for receivers Page 4 Sources of Noise Receiver V+ Power Supply Noise EMI Noise Device Noise LO Phase Noise Page 5 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 constant T = temperature in K B = 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 Page 6 Noise Power at Standard Noise Temperature (290K) Noise Source R+jX RL - j XL k = 1.38 x 10-23 joule/K T = Temperature (K) B = Bandwidth (Hz) Available noise power = Pav = kTB At 290K, Pav = 4 x 10 -21 W/Hz = -174 dBm/Hz (In deep space, kT = -198 dBm/Hz) Page 7 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 Page 8 What Is Noise Figure ? (A Practical Example) Sin / Nin = 40 dB Sin Sin Sout / Nout = 30 dB Nout Nin a) S/N at amplifier input Nin B = 25 MHz Page 9 Nout Gain = 20 dB b) S/N at amplifier output Sin / Nin Noise figure (NF) = Sout / Nout = 40 dB – 30 dB = 10 dB Definition of Noise Figure by Equation (Friis, 1944) N Nin a Nout = Na + Nin • Ga R s Noise Figure = NF (dB) = 10 log Ga Nin = kT0B , where T0 = 290K Sin / Nin = 10 log Sout / Nout FdB = Actual output noise(dBm) – Noise from “perfect” device(dBm). Page 10 Na + Nin • Ga Nin • Ga = 10 log (noise factor) = 10 log F What is the noise figure? Z0 at 290K 30dB gain 10 MHz bandwidth No = –70dBm Noise Figure = a) 24dB? b) 4dB? c) 25dB? d) 6dB? Effective Input Noise Temperature (Te) Output Noise Power N Nin R s Na -Te Page 12 0 Te Source Temperature (K) a Ga Nout Noise Temperature an alternative to Noise Figure ideal network kToB Σ kTeB To;Z0 Te Z0 No = kT0BG + kTeBG = k(T0 + Te)BG Cascade Formula G1 G2 F1 F2 NF of a two-stage system = F12 = F1 + F2-1 G1 Fn+1 - 1 NF of an n-stage system = Σ Fn+1 = Σ Fn + Σ Gn Where Σ Fn is the cumulative NF up to the nth stage, and Σ Fn+1 is the cumulative NF up to the (n+1)th stage Page 14 Importance of Knowing NF: Satellite Example Transmitter: ERP Path Losses Rx Antenna Gain Power to Rx Power to antenna: +40 dBm Frequency: 12 GHz Antenna gain: +15 dB +55 dBm -200 dB +60 dB -85 dBm ERP = +55 dBm Receiver: S/N = 4 dB Noise @ 290K Noise in 100 MHz BW Receiver NF Rx Sensitivity -174 dBm/Hz +80 dB +5 dB -89 dBm • Choices to increase margin by 3 dB: 1. Double transmitter power 2. Increase gain of antennas by 3 dB 3. Lower the receiver NF by 3 dB Page 15 Receiver NF: 5 dB Bandwidth: 100 MHz Antenna Gain: +60 dB 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 Page 16 Y-Factor (Hot/Cold) Method Output Power Nin= kB (Th or Tc) Ga Nh Slope = kBGa Nout= Nh or Nc Na R s Nc Y = Nh / Nc Na -Te Tc Source Temp (K) Th • Hot and cold noise sources are applied separately to the DUT and the output power is measured • The avalanche diode is a popular hot/cold noise source Page 17 Agilent Noise Sources Matching Pad Noise Output Bias Input Excess Noise Ratio = ENR (dB) = 10 log Th - Tc T0 (T0 = 290K) • A calibration report (ENR versus frequency) is provided with each source • Broadband and capable of electronic switching between Tc and Th • The diode is designed for stability over time • Source match is improved with a built-in matching pad Page 18 Calibrating Out NF of Measurement System Noise Source Variable Attenuator DUT F1 , G1 F2 F12 By cascade equation: F1 = F12 - • F12 (F of system) is measured with DUT connected • F2 is measured by connecting source directly to analyzer F2 - 1 , then uncertainty increases • If F12 ≅ G1 Page 19 F2 - 1 G1 Y- Factor Method NOISE DUT SOURCE PRECISION IF ATTENUATOR Th Tc Y − 1 − − 1 290 290 F = 10 log Y −1 F = ENR − 10 log(Y − 1) if TC = 290 K Where Y = Change in IF attenuator to maintain reading on detector as source switched ON and OFF Beware High DUT NF! Y = Nh = Nc Na + kThBG Na + kTcBG If F is large, Na >> kTBG and Y ≅ 1 Therefore: The Y-factor method is not suitable for very high noise figures (≥ 30 dB) Page 21 The NFA Also Measures DUT Gain Slope = kBG1G2 Nh_mea s Slope = kBG2 Nh_cal Nc_meas G1 = Nc_cal Nh_meas – Nc_meas Nh_cal – Nc_cal G1(dB) = 10 log G1 Tc Page 22 Source Temp (K) Th Devices That Can Be Tested with Agilent NFAs and SA-Based Solutions • Passive two-port devices Receiver IF • Active two-port devices • Mixers and receivers LO Mixer Passive 2-Port FET, Transistor Page 23 Amplifier LO 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 Page 24 Agilent Noise Figure Solutions Portfolio PNA-X PSA Series Highest Performance Spectrum Analyzers NFA Series Highest Performance Network Analyzer Only Dedicated Noise Figure Analyzers MXA Price Super Mid-range Signal Analyzer EXA Economy-Class Signal Analyzer ESA Series Economy Portable Spectrum Analyzers Performance Page 25 346A ENR ≅ 6 dB Na Tc Th Source Temperature (K) Output Power (W) Output Power (W) Agilent 346 Series Noise Sources 346B/C ENR ≅ 15 dB Na Tc Th 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 • 346C K01: 1 GHz to 50 GHz, nominal ENR of 20 dB • Can be used with NFA Series, PSA, ESA-E with noise figure option, and MXA/EXA with N9069A noise figure application Page 26 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 • 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 downloaded to analyzer • Source temperature is monitored by a built-in thermistor for compensation NF_102 Noise Figure Basics Page 27 January 2008 Demo Solution used for the demo: MXA N9020A + Noise Figure application www.agilent.com/find/MXA MXG Additive AWGN Impairments 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 Page 30 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 f fo time (seconds) Instantaneous frequency variations around the nominal frequency Concept of Phase Noise f0 Ideal Signal f0 Real Life Signal TYPES OF SHORT TERM NOISE MKR 9.999 999 581 8 GHz REF 8.3 dBm ATTEN 28 dB 8.28 dBm RES BW 10 Hz CENTER 9.999 999 482 GHz RES BW 18 Hz VIEW 1 Hz SPAN 500 Hz SWP 150 sec Deterministic (Discrete) - "Spurious" Continuous (Random) - "Phase Noise" UNIT OF MEASURE L(f) Usually phase noise is quantified as L(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(f) has units of dBc/Hz L (f) = LOG A L (f) AMPLITUDE Area 1 Hz bandwidth LOG f Total area under the curve 1 Hz f 0 Page 36 f 0 + fm FREQUENCY Typical Phase Noise Plot 8640B 8684B EXTCARRIER FM OFF,= + 7.70DE 4 AVERAGES FREQ + X7 REF, 09Hz 320 KHZ PK [hp] APR 4 DEV FM 13:40 / 14:02 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 -150 10 1 Hz 100 1K L 10K 100K (f) [dBc/Hz] vs f [Hz] 1M 10M 40MHz Carrier phase noise in a Doppler Radar clutter f Reflected signal from building at f Hz. Tx Rx Reflected signal from car at f+ ∆f Hz. How local oscillator phase noise can obscure the returned Doppler signal from the moving object. LO phase noise improvement Doppler signal unresolved Doppler signal resolved Noise in Digital Radio Amplitude Noise Phase Noise Page 40 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 Page 41 Phase Detector Technique Low Freq. Spectrum Analyzer displays Sφ(fm) Phase Detector Unit Under Test Reference (same freq. as UUT) Spectral density of phase Sφ(fm) = fluctuations Reference Source/PLL Measurement Technique MICROWAVE DOWNCONVERTER BASEBAND TEST SET ∆Vrms(f) OSCILLATOR UNDER-TEST = Kφ ∆φ rms(f) [V] PHASE DETECTOR BASEBAND ANALYSIS HARDWARE SIGNAL CONDITIONING BASEBAND OUTPUT SIGNAL REFERENCE SOURCE RF OUT TUNING VOLTAGE PHASE-LOCK LOOP The Spectrum Analyzer Method RF Spectrum Analyzer Unit Under Test Measure C/N at the required frequency offset. The Spectrum Analyzer Method The Spectrum Analyzer Method • How to define Phase Noise on a spectrum analyzer? P0 4 elements: dBc/Hz 1) Carrier frequency 2) Offset freq. from carrier freq. 1 Hz BW 3) Power spectral density (in 1 Hz BW) 4) Relative to carrier power in dBc dBc/Hz @ offset freq. fm Assuming AM noise << PN f0 fm (offset freq.) The Spectrum Analyzer Method 8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz Oscillator Under-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 • 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 Page 48 Overview of Agilent PN Measurements solutions • Direct Spectrum Analysis PSA/Opt. 226 • Carrier removal+ BB Analysis E5052B Signal Source Analyzer ESA/Opt. 226 856X/85671A MXA/EXA with N9068A • PN measurements made easy by a general-purpose SA w/ PN personality E5505A PN Measurement Solution • More focused measurements • Dedicated to component tests 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 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 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 Noise application MXG vector signal generator www.agilent.com/find/MXA www.agilent.com/find/MXG MXG Additive Phase Noise Impairments