millimeter signal measurements: best practices, solutions, and … · 2012. 5. 15. · measurement...

5/14/2012

© Agilent Technologies, Inc. 2012 1

Copyright © 2012 Agilent Technologies

Millimeter Signal Measurements:

Best Practices, Solutions, and

Accuracy

Ben Zarlingo Product Manager, Signal Analysis

Microwave & Communications Division


© Agilent Technologies 2012

Agenda

Millimeter Measurements Discussion

– Information

– Best Practices

– Optimizing Performance

Special Hazards, Problems

Choosing Measurement Tools, Alternatives

Millimeter Signal Measurement Solutions

References, Resources

5/14/2012




What is Millimeter-Wave?

Wavelengths ~≤ 10 mm, f ~≥ 30 GHz

Where Everything Gets

– Difficult

– Small

– Expensive

– Lossy

– Delicate

– Inflexible

– Banded (if not narrowband)

Graduate Work for the Electrical Engineer

Commercial/Consumer: 60 GHz Wireless HD

$600 Transmitter + Receiver $300

$180



Millimeter Performance Expectations

Performance Generally Less Ideal

– Harmonic architecture (phase noise, conversion loss, etc.)

– Path/insertion losses, impedance mismatches

– Preselector filtering

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New Calc. Method for Mismatch Uncertainty

Mismatch Uncertainty typically

dominates

Better understanding, verification of

probability distributions

Rayleigh model is an excellent fit,

provides more accurate but still

conservative estimates of uncertainty

due to mismatch

Result: Lower Uncertainties due to mismatch

by factor of 3 to 6

AN 1449-3 Power Measurement Uncertainty

Per International Guidelines (updated April 2011)



Better Calculations Indicate

a Rayleigh Distribution

Probability density of the magnitude of the reflection

coefficient is Rayleigh distributed if the probability

density of both complex parts is Gaussian distributed

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Validating Assumptions

with Real World Examples



Importance of Cables, Connectors

Influence of Materials, Structures, Geometries

Amplitude, 30-50 GHz

– Dropouts due to moding* – Amplitude, phase errors

– Errors with 3.5mm also, though perhaps more repeatable

– Error < 2dB in this example

• Good enough?

• Repeatable enough?

Performance Gain from cables may be very Cost-Effective

2.4 mm

SMA

*Moding: Excitation of the first

circular waveguide propagation

mode in the coaxial structure

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Plastic vs. Air Dielectric

PTFE vs. Air, Beads

– Air for metrology grade & many instrumentation grade

Many Other Tolerances & Construction Differences Usually

Accompany Dielectric Change

SMA

3.5 mm



Use A Torque Wrench for Consistency

“Wrench Lift Stress” is a special concern with several

devices connected or a long device or adapter(s)

Lift

Angle between

wrenches should

be less than 90

deg

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Torque Values & Wrench Sizes



Torque Problem Example

Loose Cable Amplitude

Error

– Significant for you?

What if it is variable and

inconsistent?

Phase Variability

Sufficient Torque

– Enough torque to properly mate

surfaces and to produce a strain

that will prevent loosening due

to vibration and/or thermal

cycling

– Not enough to damage or distort

connectors, changing geometry

5/14/2012




Connector Grades

Metrology Grade – Highest precision, performance, repeatability

– Often slotless female center conductors (repeatable, lower inductance)

– Often used in calibration/verification kits

– Expensive, long life

PSC = Precision Slotless Connector – Typically metrology grade; PSC versions available for 3.5mm, 2.4 mm

Instrument Grade – Excellent repeatability, long life

– Often slotted female center conductors

General Purpose or Production Grade – Typical on components, cables, microstrip

– Inspect before connecting to better grades (analyzers), use adapter

– Limited connection cycles



Connection Consistency

Consistent Connections Improve Repeatability – Same Cables (cable loss may be more than 3 dB/meter at 50 GHz)

– Same connectors, adapters

– Same cable routing

Every Connection & Transition is Imperfect – Insertion loss (one adapter = up to 1 dB loss at 50 GHz)

– Impedance change

– Bending can change cable characteristics

– Consider semi-rigid cable

Analyzer Accuracy is Improving Smaller Errors Matter

Repeatability may be More Important than Absolute Accuracy

Standardize on Highest Frequency Connectors? – Consistency, but slightly higher loss at lower frequencies

5/14/2012




mm-Frequency Connectors and Intermating

24 pt level 1

– 20 pt level 2

• 18 pt level 3

http://na.tm.agilent.com/pna/connectorcare/What_mates_with_what.htm

Uses a plastic (PTFE) dielectric



Torque for Intermating

Proper Torque for Intermating Can Depend on Gender

– Example 1: A 56 N-cm. torque wrench should be used to connect male

SMA connectors to either 3.5-mm or 2.92-mm (K) connectors

– Example 2: A 90 N-cm torque wrench should be used to connect male

3.5-mm or male 2.92-mm connectors to mating female connectors

including SMA

Precision Connectors use Higher Torque

– Use lower torque with SMA SMA

– Use lower torque with male SMA male precision

5/14/2012




Important Lower Frequency Connections

in a High Frequency System

Connectors Make a Difference in Some Low Frequency

Measurements!

3.5 mm or SMA to BNC

Precision BNC connections on Oscilloscope



Coax & Waveguide Comparison

Flexible

Wide frequency range

Easy to change routing

Light weight

Can carry DC bias

Can be less expensive

Good match for component meas.

Disadvantages

– Lossy, increasing with frequency

– Can be delicate

– Limited power handling

Low loss

High power handling ability

Mechanically durable

Disadvantages

– Inflexible

– May need custom construction (expensive)

– Time delays for construction and reconfiguration

– Frequency range ≤ 1 octave

– Transitions needed to connect to analyzers, other coaxial elements

Coax Waveguide

5/14/2012




Hardware Features & Signal Processing

Improve Performance

Low Noise

Path

Noise Floor

Extension

19

• Standard

• With LNP

• With NFE



Agenda

Millimeter Measurements Discussion

– Information

– Best Practices

– Optimizing Performance

Special Hazards, Problems

Choosing Measurement Tools, Alternatives

Millimeter Signal Measurement Solutions from Agilent

References, Resources

5/14/2012




Beware of DC at Analyzer Input

Millimeter Agilent PXA, PSA Have No DC Block

Why? Internal DC Block Would Compromise Performance

Add External DC Block if Needed

Front Panel Male Connector

Protects Analyzer

– Discourages direct mating with

typical coaxial male connector

– Encourages use of connector saver

– Male connector more durable,

less likely to be damaged from

improper mating



Adapters as Connector Savers

Connectors are “Consumables” with a Limited Lifetime

Non-Millimeter Instruments Typically use Female Front Panel Connector – Use to mate male cables with

male analyzer connector

– Consider other types as needed in your application

Note “Flats” for Wrenches to Prevent

Connector Rotation

5/14/2012




Damage Hazard: Non-Captive SMA Nut

Danger from SMA Male to 2.4 mm and 1.85 mm Female

3.5 mm to 2.4 mm adapter

3.5 mm end 2.4 mm end

SMA with non-captive nut

and extended center pin SMA with non-captive nut can be inserted into

2.4 mm



Electrical Damage

High Frequencies Small Size Electrically Delicate

Burnout from Excess Power

Burnout from Source Transient

Static Zap

Detecting Damage (other than outright failure)

5/14/2012




Microphonics, Other Movement

Phase Noise, Close-In Modulation

Can Affect Analyzer, Connections, DUT

Mitigating Microphonics

– Separate table, mounting

– Use isolating feed/pads/mounts

– Stabilize or support cables, waveguide

– Use phase-stable cables

Vibration, Thermal Cycling may Loosen Connections

– Torque check as part of measurement routine



Alignment, Calibration, Correction

Calibration: Initial & Periodic Adjustment, Verification – Factory, service center, calibration lab

Alignment: Frequent Self Adjustment – Automatic adjustment compensates for temperature, drift, aging

– Alignment can affect dynamic range

Correction/Compensation – Often included in demodulation operations

– Substitution (power meters, etc.)

– May be only practical way to dramatically improve accuracy

– Enter parameters in analyzer for front-panel operation

– May be manually cumbersome or need switching

Perform Alignments Frequently and Whenever Measurement conditions Change – Temperature sensitivity generally goes up with frequency

5/14/2012




Preselector Centering, Tuning

YTF Preselector (Filter)

– YTF operates open-loop

– Preselector tuning is

characterized automatically by

analyzer for full frequency

range

– Centering performed by

analyzer, very brief operation

– Perform centering for best

amplitude accuracy at a single

frequency

– Centering is initiated by user;

not part of normal alignment



Preselector Affects Wideband Signals

Solution: Preselector Bypass

“Microwave Preselector Bypass”

Hardware Option

Removes YIG-Tuned Preselector Filter from

Measurement Path

– Essential for wide-bandwidth measurements

– Removes preselector insertion loss but passes

wideband noise; effect on analyzer DANL

is variable

– May allow other signals into measurement

– Can tune to signal with preselector in place

and then bypass

Preselector

Bypass Path

Norm

Bypass

5/14/2012




Choosing Measurement Tools

Where Should the First Mixer Be?

Why Not a Millimeter Oscilloscope?

Recent Developments in Performance, Functionality



Millimeter Signal Measurement Solutions

5/14/2012




External Mixing and Downconverters:

Analyze Signals to 750 GHz

New M1970 V/W

50-110 GHz

11970 Series

millimeter mixers

18 GHz to 110 GHz

≥ 110 GHz

Legacy Mixers NEW

Smart Mixers

Third Party Mixers



External Mixing Bypasses

First Internal Mixer

5/14/2012




Agilent 11970 Series Harmonic Mixers

Connection Detail



Basic Setup: External Mixer

34 34

5/14/2012




Conversion Loss Corrections



M 1 9 7 0 V / W W A V E G U I D E H A R M O N I C M I X E R S Mixer Products, No Signal ID

5/14/2012




M 1 9 7 0 V / W W A V E G U I D E H A R M O N I C M I X E R S Signal ID: Image Shift



M 1 9 7 0 V / W W A V E G U I D E H A R M O N I C M I X E R S Signal ID: Image Suppression

Note: Unstable signals may be removed

5/14/2012




WAVEGUIDE HARMONIC MIXERS

M1970V: 50 - 75/80 GHz

M1970W: 75 - 110 GHz

Ease-of-Use & Simplification of Test Setup

– USB plug-and-play

• Auto detection & parameter download

• Auto configure frequency range, harmonic number

• Auto amplitude correction

• Auto LO power adjustment with

up to 3m cable loss

• Single coaxial IF/LO interface

Improved Performance and Accuracy

– Improved conversion efficiency to 25 dB

• Better DANL by 6 dB

• Enhanced Calibration Accuracy to+/- 2.2dB

39



40

External Mixer Performance & Functionality

Extend to 325 GHz and

beyond

• Supported measurements

•Spectrum analysis

•PowerSuite

•N9068A phase noise meas. app.

• Supported external mixers

•M1970V and M1970W

•11970 Series

•Virginia Diodes Inc.

•OML Inc.

•Farran Technology Ltd.

5/14/2012




Why Not a Millimeter Oscilloscope?

Indeed, Why Not?

One box solution

Very wide bandwidth

Multiple simultaneous channels

Baseband coverage

Good in-band performance

VSA functionality

– Expensive

– Limited dynamic range

– Very wideband, not internally filtered

– Very large sample count for some measurements

• Decimation, resampling, digital LO performed by DSP

• Some demodulation measurements can be slow

Agilent 90000 X-Series Oscilloscopes

True 33 GHz analog bandwidth



Dedicated Upconverters &

Downconverters for Wideband 60 GHz

5/14/2012




802.11ad Test Block Diagram

WiGig & WiHD

43



Dedicated Upconverters & Downconverters

Advantages

High sensitivity/ low conversion

loss

– Suitable for antenna applications

– Useful for applications where devices

do not have external connectors

Wide Modulation bandwidth

Flexible cabling to couple directly

to signal or device under test

Disadvantages

Banded, limited operating

frequency

Require external local oscillators

Not preselected

Not an off-the-shelf product

Expensive compared to external

mixers

Not a source or analyzer

– Typical application includes signal

generator, modulation source,

separate low frequency or baseband

analyzer & VSA software

5/14/2012



© Agilent Technologies 2012 October 27 2010

PXA as a Millimeter Downconverter PXA Downconversion Extended to 50 GHz

Adjustable IF Outputs

Fast Video Out, Including Preselector Bypass

Fast Log Video Out

Temporal analysis of radar pulses and pulsed EW RF

Trigger other devices

Wideband Output, 600-800 MHz Bandwidth

Digitize with Oscilloscope or Other

Analyze with 89600B VSA

50 GHz

Infiniium

DSO90204

2.5 GHz + VSA



High Band IF Output Examples Millimeter Frequencies, Wide Bandwidths

Preselector Bypass On/Off

600 MHz BW, 5

dB Flat

Offset to CF 500 MHz

800 MHz BW, 8 dB Flat

5/14/2012




PXA Fast Log Video Output

Connect to Oscilloscope for Temporal Analysis

of Radar and EW Pulsed RF

Use Fast Video Out to Trigger Other Equipment

Select from Front Panel:

• Tunable IF Out

• 2nd IF Out

• Trigger Out



Fast Video Output, Preselector Bypass

High Band Example,

Low Band Several ns slower

– Freq = 9.6 GHz

– PW = 100 ns

– Span = zero-span

– Sweep = single

– Path = Bypass

– Rise time = 13.91 ns

5/14/2012




Additional Information

Fundamentals of RF and Microwave Power Measurements (part 3) Power Measurement Uncertainty Per International Guidelines AN-1449-3, April 2011 http://cp.literature.agilent.com/litweb/pdf/5988-9215EN.pdf

Average Power Sensor Uncertainty Calculator http://www.home.agilent.com/upload/cmc_upload/All/Average_Power_Sensor_Uncertainty_calculator_Rev6.xlsx

Coaxial Connector Overview www.home.agilent.com/upload/cmc_upload/All/CoaxialConnectorOverview.pdf

What Mates With What http://na.tm.agilent.com/pna/connectorcare/What_mates_with_what.htm

Connector Grades http://na.tm.agilent.com/pna/connectorcare/Connector_Grades.htm

Intermateability of SMA, 3.5 mm AND 2.92 mm Connectors

Microwave Journal (Cables & Connectors Supplement) 3/2007, available at www.gore.com

Connector Care Quick Reference Card http://cp.literature.agilent.com/litweb/pdf/08510-90360.pdf

Principles of Connector Care http://cp.literature.agilent.com/litweb/pdf/5954-1566.pdf

External Waveguide Mixing and Millimeter Wave Measurements with Agilent PSA Spectrum Analyzers (app-note 1485) http://cp.literature.agilent.com/litweb/pdf/5988-9414EN.pdf



Questions?

http://cp.literature.agilent.com/litweb/pdf/5988-9215EN.pdf



http://www.home.agilent.com/upload/cmc_upload/All/Average_Power_Sensor_Uncertainty_calculator_Rev6.xlsx

http://www.home.agilent.com/upload/cmc_upload/All/CoaxialConnectorOverview.pdf

http://na.tm.agilent.com/pna/connectorcare/What_mates_with_what.htm

http://na.tm.agilent.com/pna/connectorcare/Connector_Grades.htm

http://www.gore.com/

http://cp.literature.agilent.com/litweb/pdf/08510-90360.pdf









5/14/2012




11970 Waveguide Harmonic Mixers

Model Freq

(PSA)

N

(PSA)

LO

(PSA)

Max

LO

(LPF)

Freq

(PXA)

N

(PXA)

LO

(PXA)

11970A 26.5-40 8- 3.35-

5.04 5.2

26.5-30.9 6- 4.47-5.2

30.1-40 8- 3.8-5.04

11970Q 33-50 10- 3.33-

5.03 5.2

33-41.3 8- 4.17-5.2

37.7-50 10- 3.8-5.03

11970U 40-60 10- 4.03-

6.03 6.2 40-60 Same Same

11970V 50-75 14- 3.59-

5.38 5.6

50-66.9 12- 4.19-5.6

52.9-75 14- 3.8-5.38

11970W 75-110 18- 4.18-

6.13 6.2 75-110 Same Same

•11970 mixer models selectable in UI (11970A/Q/U, etc.), for parameter setup

• Mixer conversion loss data at different harmonic numbers is provided on CD

• External diplexer required with PXA (ex. N9029AE13)

• PXA does not support preselected mixers

11970 Series

millimeter mixers - 18

GHz to 110 GHz,

11970K not supported

PSA/PXA use same harmonic numbers with same conversion loss data

PSA/PXA use different harmonic numbers, require different conversion loss

data

millimeter signal measurements: best practices, solutions, and … · 2012. 5. 15. · measurement...

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