Advanced Passive Intermodulation (PIM) Test System · PDF file© 2013 Agilent Technologies...

© 2013 Agilent Technologies

Advanced Passive Intermodulation (PIM)

Test System

August 29, 2013

Presenter: Steve Ludvik

President

Power Technology Solutions


• Introduction

• Overview of Passive Intermodulation (PIM) and their effects

• New telcom service provider and regulatory requirements

• Challenges for Designers, Manufacturing, Test Engineers and QA

• Review of commercially available equipment

• Agilent PTS Advanced PIM Test System

• PIM and S-parameter Analysis

• PIM Location Analysis (PLA)

• Summary & Questions

Agenda


• What is Passive Intermodulation (PIM)?

- Nonlinearity generated by passive elements within a transmitter system

from a variety of physical phenomena

- Causes : Junctions of dissimilar metal junctions, magnetic materials, piezoelectric

effects and particulate contamination, among others.

• Why is it a problem?

- Occurs after final filtering within the transmitter and cannot be removed

- Signal levels can exceed the incoming received signals resulting in loss of capacity

• Why now?

- Well known effect in satellite and terrestrial radio systems

- PIM has become critical parameter in next generation telecom system due to

bandwidth demands

• How to improve?

- Measure and understand primary causes

- Guide manufacturing and test methods

Introduction


• Linear Amplifier:

-30 to -40 dBc IMD levels

• Linearized Amplifier (Feedforward, Pre-distortion,etc)


• PIM Signal Levels


Comparison of IMD Levels


PIM Problem

43 dBm

43 dBm

-110 dBm

Link Budgets

1.99 1.93 1.87

PCS 1850-1910 MHz Uplink

1930-1990 MHz Downlink


Key System Components

Duplexer

Antenna Cable

Switch Load


IEC 62037 Standards

• IEC PIM Standards

- Developed by working committees

- Define practices and methods of measurement

- Specific standards

62037-1 General Methods

62037-2 Coaxial Cable Assemblies

62037-3 Connectors

62037-4 Coaxial Cables

62037-5 Filters

62037-6 Antennas

• Recognize effects of Multiple PIM sources

- PIM generated by point sources with constructive/destructive interference

- Effects of shock and vibration

• PIM Specifications are both country and vendor defined

eg China - 155dBc at system level


Measurement Accuracy

Sources of PIM Measurement Errors

- System PIM level (per chart)

- Power Meter Accuracy +/- 0.02dB

- Receiver Cal. Accuracy +/-0.1dB

- Power Setting +/- 0.75dB

- Mismatch errors +/- 0.05dB

- Mechanical stability during measurement

System PIM Level Error Contribution


Comparison of Measurement Systems

Approach

Various

User Developed

Agilent Solution


New Test System

Innovative, Flexible PIM Test System

Multiband capability

Based on IEC-62037 PIM Test Guidelines

Combines standard Agilent test equipment

E5072A, EXG and P7022 Test Set

Reduced mechanical handling to provide PIM

and S-parameter data

Reduce test time, accurate measurements

provides cost effective solution


Product Configurations

SINGLE PORT

AMPS/PCS

DUAL PORT

Cross-Polarized Antennas

Cables


Test System Features

Dual Band: AMPS800 and PCS1900

Test: PIM and S-parameter measurement

Components: Cables / Antennas/Filters/Switches/Loads

Performance: <165dBc

Benefits:

Speed and flexibility of measurement

Cost effectiveness – test speed, accuracy & simplified connectivity


Hardware Configuration

EXG : N5171B

ENA : E5072A

P7022 SM

P7022 PM

PIM Test Module

2 x 4RU

Firmware : Customer specific open VBA code

Hardware :


Measurement Examples

Calibration

Test Modes

- Fixed Frequency

- Sweep (UP/DOWN)

- IM Spectrum

- S-parameter

- PLA

AMPS

PCS


Calibration Dashboard

RX

Band Setup Receiver Calibration

- Define Test File

- Power Meter / ENA Sequence


Measurement Mode -AMPS

RX

FIXED SWEEP Down/Up IM Spectrum


Test Dashboard - PCS

RX

Measurement Mode Test Mode


PIM & S-parameter

RX

Test Mode: PIM Sweep Down Test Mode: S11 50MHz -4.5GHz

S-parameter PIM


AMPS – Data

DUP REF

LOAD Int Cable

TX

F-F RX

TEST CABLE

RCVIL

RX -160dBc

Test Time : <1sec

# Points : 11

IFBW : 10Hz

Test Window


AMPS – Data

DUP REF

LOAD Int Cable

TX

F-F

CAL

RX

TEST CABLE

SWEEP MODE : UP

RCVIL

RX

-160dBc


PCS – Data

DUP REF

LOAD Int Cable

TX

F-F

CAL

RX

TEST CABLE

SWEEP MODE : DOWN

RCVIL

RX

-160dBc


PCS – Data

DUP REF

LOAD Int Cable

TX

F-F

CAL

RX

TEST CABLE

SWEEP MODE : UP

RCVIL

RX

-160dBc


Data – Summary

AMPS PCS

Test Cable Test Cable


Measurement Enhancements

Fault Troubleshooting :

- FDR/TDR Distance to Fault (DTF)

Wideband 2.5-8.5GHz bandwidth

Use built-in E5072A analysis function (AN1287-12)

Transmission & Reflection Modes

Range: 10 usec Resolution: 0.07 nsec

- FDR/TDR PIM Location Analysis (PLA)

Bandwidth limited by cellular/PCS filters (25-60MHz)

Use IM amplitude/phase for TD transform

Range: 300 nsec Resolution: 30 nsec


Principle of PIM Location Analysis (PLA)

ENA based PIM

measurement

solution w/ circuit

for location analysis

Low PIM

load

1) Measures IM signal

as vector value over

frequency

2) Convert time

domain by IFFT and

locate distance

Frequency

Time

PIM source

DUT

Am

plit

ude

Electrical length

Electrical length (s)

Am

plit

ude


Measurement Example – Using ENA for PLA

-100

-95

-90

-85

-80

-75

-70

-65

-60

-3.00E-07 -2.00E-07 -1.00E-07 -4.00E-21 1.00E-07 2.00E-07 3.00E-07

79.9ns

8.2ns 88.1ns

ENA based PIM

meas. system

w/ circuit for

location analysis

High PIM DUT (-110dBc@43dBm input)

ENA based PIM

meas. system

w/ circuit for

location analysis

High PIM DUT (-110dBc@43dBm input) Setup1

Setup2

Setup1

Setup2

Measurement Result of PIM Location analysis (Displayed in time domain)

H+S low PIM cable(10m, 40ns) LIS-C9-11716-11716-10000


Response Resolution

Response resolution is determined by frequency range we can sweep

Response resolution = 1.2 / Fspan (@minimum window)

Response resolution is defined as bandwidth of impulse response for 50% level

Wider frequency range, the smaller resolution

In principle, frequency range we can sweep is determined by duplexer in the test

system

If multiple PIMs are located in the response resolution, measurement result shows

the combination of multiple PIMs.

Rx Tx BW for

IM3 sweep

Response

resolution (ns)

AMPS800 824 849 869 894 5 240

GSM900 880 915 925 960 15 80

DCS1800 1710 1785 1805 1880 55 22

PCS1900 1850 1910 1930 1990 40 30

Response resolution for the each band (Minimum window)


Multiple PIM Example


Range Resolution


Comparison of DTF and PLA


System Performance Summary

• Dual Band: AMPS800 and PCS1900

• PIM and S-parameter measurement ( cables/antennas/switches /filters/loads)

• Enhancement for Distance to Fault (DTF)and PIM location analysis (PLA)

• Performance: <165dBc

• Agilent PTS solution offers speed and flexibility of measurement

• Open Architecture

• Cost effectiveness – test speed, accuracy & simplified connectivity

32

EXG : N5171B

ENA : E5072A P7022

P1926

P4590

S8519

S9018

S8021

S2126

S4580

AMPS/PCS 850/1900 MHz

GSM/DCS 900/1800 MHz

iDEN/UMTS 800/2100 MHz

UMTS 2100/2600 MHz

LTE 450/800 MHz

Application

Coverage

SFM

PMOD

SWM PMOD

System Configurations


Summary

• Overview of PIM Phenomena

• Highlighted PIM criticality to next generation Telcom systems

• Described PIM Test System with open architecture

• Presented a new measurement tool to identify sources suited for :

Design, Manufacturing Test & QA


Resources / Contacts

Resources:

www.agilent.com/find/pts

www.agilent.com/find/pim

http://cp.literature.agilent.com/litweb/pdf/5991-2194EN.pdf

Contact:

Steve Ludvik

Power Technology Solutions

Tel: 650-814-0627

Email: [email protected]

http://www.agilent.com/find/pts

http://www.agilent.com/find/pim





Thank You !

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