K&L Microwave Filtering Modules for IMD Measurements over 4G-LTE Bands

September 12th, 2013

2

Objectives • Typical IMD Levels and Applications

• Emission Monitoring Solutions – Measuring without Disrupting

• Low PIM Filtering Solutions - Building Blocks for Reducing Un-certainty of Measurement

High-Pass/Low-Pass Duplexer (HP/LP)

Band-Pass/Band-Stop Duplexer (BP/BS)

Duplexers (BP/BP, LP/BP)

Triplexers (BP/BP/BP)

Band-Reject Filters with Band-Extenders (BRF/BE)

• Build Your Own IMD Test Setups - Control your Dynamic Range

• The “Blockers” are everywhere: New Filtering Solutions …

The “Quadraplexer”: BRF/BP/BP

• “Triple Beat Test”- a Real Challenge

• The Road Map to a Complete and Customized Switched Test System

• Q/A

3

Typical IMD Levels and Applications

IMD[dBc]

P[dBm]

IM[dBm]

IP3[dBm]

3rd

3rd

5th

5th

f1

f2

f

[dBm]

Tx Rx Rx

P[dBm] IM[dBm] IMD[dBc] Application

2x(+43) -113* 156 Base Station, PA,

Antenna:

“High-Power”

2x(+43) -118 161 Distributed Antenna

Systems (DAS)

2x(+26),

(+26)+(+16),

(+26)+(-16)

-140 166 Semi-con., Small Cell,

Chipsets, Switches,

Tunable Caps, IC, etc.:

“Low-Power”

2x(+43) -128 171 PIM Analyzers

•1dBm reduction in power carriers (f1 and f2) yields ~2.2dBm reduction in IM 3rd

IM 3rd = (2*f1-f2) and (2*f2-f1) IMD = P-IM For n=3: IP3 = P+IMD/2 “PIM” is IM created by a Passive Source

1n

IMDPIPn

Can you tell which measurement is tougher? Answer:

Only 10dBm difference!

150.426)(432.2113

4

Spectrum Analyzer

SPDT

Carriers

Near Zone (LPF) Far Zone (HPF)

Notes: • Emission monitoring is also “Forward” IMD measurement • The HPF and BRF need to reject the carriers such that -60dBm

max. can travel to the spectrum analyzer • Avoid reflected waves back to the DUT or to the source • Low PIM 50Ω Termination (marked with a in this

presentation) is used only if the carriers are passing through • The SPDT is non-reflective, but not specified for PIM, since

carriers don’t travel through

Low PIM 50Ω Termination

Non-Reflective

Emission Monitoring Solutions: Near and Far Zones

5

BP/BS Duplexer Applications

S11 “Matched” Band-Reject Filter

S11 “Matched” Band-Pass Filter Attenuator

Attenuator

FDD

TDD

Often used to increase the Dynamic Range of the S/A by attenuating the unwanted signal from mixing …

Often used to improve Impedance Match with the DUT, while drawing more power from the PA …

Traditional Setup

Improved Setup

6

BP/BS Duplexer

A complete list of available Band-Pass/Band-Stop duplexers is available at the following link: http://www.klmicrowave.com/product_attach/1/_plk287_1_lowpimhp.pdf If your specific need is not covered here, contact K&L for a custom design.

7

BP/BS Typical Data

8

BP/BS Typical Data

The flatter the PIM response, the fewer the IMD sources.

9

High-Pass/Low-Pass Duplexer

Applications: • Emission Monitoring • 2nd and 3rd Harmonic Tests from a Single Tone

Notes: • The LPF passes the fundamental carrier and rejects the Harmonics, preventing them

from entering the DUT • The HPF terminates Harmonics generated by the PA

DUT

Spectrum Analyzer

2fo, 3fo….

fo

fo

PA

10

Low PIM High-Pass and Low-Pass Filters

11

Typical Data (Two +43dBm Tones)

12

Two Tones-Single Amp-IMD in Rx Band Setup #1a

Notes: • Signals are combined pre-amplification state. • Single amplifier produces two-tones and large IMD levels. • Isolator is an IMD source. • Tx filter is required of high rejection levels >-115dBc. Carriers are rejected back into the

isolator. • Rx filter is required to attenuate the carriers to <-60dBm, to reduce IM products inside the

Spectrum Analyzer. • Hard to obtain low IMD base line.

Applications: • Two Tones - 3rd IM “Reflected” and “Forward” in the Rx Band

DUT

Tx

Rx

Tx

Rx

Spectrum Analyzer

SPDT

Non-Reflective

13

Two Tones-Single Amp-IMD in Rx Band Setup #1b

Notes:

• “Reflected Mode” only

• Difficult to obtain a base line

DUT

Tx

Rx

Spectrum Analyzer

14

Two Tones-Two Amps-IMD in Rx Band Setup #2a

Notes: • Most popular; cheap, easy to assemble • Amplifiers seem to be isolated by roughly 50dB • Reflected TX1 and TX2 signals are travelling back to isolators, by nature ferromagnetic

devices • Secondary IM products are generated, due to reflections, which tends to raise the base line of

the setup • Tx filter must present at least 100dB rejection to the Rx band, preventing IM products from

the iso-coupler from travelling to the Spectrum Analyzer • Rx filter needs to present 100dB to Tx band, reducing +43dBm tones from mixing inside the

Spectrum Analyzer • Amplifiers need to present extra 3.5dB gain to compensate for the 3dB hybrid and isolators

DUT

Tx

Rx

Tx

Rx

Spectrum Analyzer

SPDT

Non-Reflective

TX1

TX2

15

Notes:

• “Reflected Mode” only

Two Tones-Two Amps-IMD in Rx Band Setup #2b

DUT

Tx

Rx

Spectrum Analyzer

TX1

TX2

16

Notes:

• Two narrow band filters substituted for the -3dB Hybrid

• The output duplexer covers the entire down-link and up-link bands

• Input duplexer must be of high quality (always), since it’s difficult to pinpoint IMD sources

IMD Test Setup #3

DUT

Spectrum Analyzer

Tx2

Tx1

Tx2

Tx

Rx

Tx1

Applications:

• Inter-Cell Interference in “Forward” mode

17

Duplexers (BP/BP) – 100dB Tx-Rx & 161dBc PIM (Two +43dBm Tones)

A complete list of available Low PIM Band-Pass/Band-Pass Duplexers is available at the following link: http://www.klmicrowave.com/product_attach/2/_plk315_1_DASLowPIMds.pdf If your specific need is not covered here, contact K&L for a custom design.

18

Notes: • IM test in “Reverse” and “Forward” mode • Base line is easy to maintain • All ports are tuned for -20dB return loss • Easy to maintain and debug problems

Two Signals-BP/BP/BP (Triplexer)-IMD Test Setup #4a

DUT

Spectrum Analyzer

Tx2

Tx1

Tx2

Rx

Tx1

Tx2

Rx

SPDT

Tx1

Non-Reflective

19

Notes: • Amplifiers are isolated by 75dB • Rx filter presents 100dB in Tx band • Tx1 and Tx2 are relatively narrow (about 1/3 of down-link bandwidth), reducing the out-of-band

noise of the amplifiers • Tx2 can be dedicated to a “Blocker” signal • Triplexer can be self-tested - easy to maintain

Tx1

DUT

Spectrum Analyzer

Tx1

Tx2 Tx2

Rx

Two Signals-BP/BP/BP (Triplexer)-IMD Test Setup #4b

A complete list of available Low PIM Triplexers is available at the following link: http://www.klmicrowave.com/_upload/3GPPTriplexers.pdf If your specific need is not covered here, contact K&L for a custom design.

20

Notes: • DUT is subjected to two signals, one from each port • Filtering the signals provides flow and avoids reflections, reducing possible IMD sources

DUT

Spectrum Analyzer

Tx2

Tx1

Tx2

Rx

Tx1

Tx2

Rx

SPDT

Tx1

Non-Reflective

Two Signals-Both Ports of DUT-IMD Test Setup #5

21

Low PIM Triplexers (BP/BP/BP)

RX

f1 f2 f3 f4 f5 f6

75 dB

100 dB

1.5dB

TX1 TX2

• Triplexers can be self- tested

• Easy to maintain the base line

Tx1

Spectrum Analyzer

Tx1

Tx2 Tx2

Rx

22

The “Blockers” are Everywhere! BRF/BPF/BPF

Notes: • Tx, Rx, and BRF are isolated by 75dB • All three filters are tuned for 20dB return loss to reduce uncertainty of measurement • BRF provides 20dB of match over all specified “Blockers”

Electrical Scheme Frequency Response

Tx

Rx

BRF Tx+Rx

(Quadraplexer)

23

Extending the Passband of the Triplexer-“Reverse” IMD

The Quadraplexer:

• Enables all combinations of “Blockers” and Tx signals

Tx

Rx

BRF Tx+Rx

“Bloc-kers”

DUT

Tx

Spectrum Analyzer

SPDT

Non-Reflective

“Blocker” Signal Gen.

24

LTE Band 2: Actual Data

Tx: 1850-1910MHz (1880MHz)

Rx: 1930-1990MHz (1960MHz)

Blockers: 80MHz, 1800MHz, 3800MHz, and 5800MHz

25

LTE Band 2: Actual Data (continued)

26

• Enables mixing the Tx signal with many “Blockers” through the BRF

• Limited only by the BRF upper-passband match

• Easy to maintain

Tx + “Blocker” IMD Test Data

Tx1 (+26dBm) @ 1855MHz Tx2 (+16dBm) @ 1775MHz 3rd IMD (-147dBm) @ 1935MHz

27

LTE Band 2: Actual Data (continued)

28

LTE Band 2: Tx signal and “Blockers”

29

Tx + “Blocker”-IMD Test Setup #6a

Notes:

• “Reverse” and “Forward” IMD measurements

• Easy to maintain and debug

Spectrum Analyzer

Tx Tx

Rx

BRF Tx+Rx

Tx

Rx

BRF Tx+Rx DUT

SPDT

Non-Reflective

“Blocker” Signal Gen.

30

• Enables exposing the DUT to one Tx signal and any “Blockers” with port “swapping” capability

• Enables measurements for “Reverse” and “Forward”

Tx + “Blocker” Port Swapping-IMD Test Setup #6b

Tx

Rx

BRF Tx+Rx

“Bloc-kers”

DUT

Spectrum Analyzer

SP4T

Non-Reflective

“Blocker” Signal Gen.

Tx

Rx

BRF Tx+Rx

“Bloc-kers”

Tx SP2T

Non-Reflective

SP2T

Non-Reflective

31

Mix-n-Match (LTE Band 7)

DUT

BPF2620-2635

BPF2675-2690

BPF2550-2595

BPF2620-2690

BPF2500-2570

SpectrumAnalyzer

Triplexer/Duplexer

32

Triple Beat & 3rd IMD for RF Switches Triple Beat and IMD for RF Switches emulates two Transmit carriers of the mobile up-link,

separated by 1MHz, entering the DUT, along with a “Jammer” (“Blocker”), representing a weaker signal in the mobile down-link (Receive) band, from a different system.

http://www.ni.com/white-paper/14506/en

• IM 3rd are f3-(f2-f1) and f3-(f2+f1)

• Concerns with the proposed block diagram : The two Tx carriers mix

with the “Jammer” in the CW source

Limited isolation between the amplifiers - return loss limit.

“Jammer” signal travels directly into the Spectrum Analyzer

33

Triple Beat Filter Based - Phase 1

Notes:

• “Jammer” CW source is now protected from the two TX signals

• One problem remains: Energy of TX1 and TX2 is reflected back from Tx Filter and DUT, F1 goes to AMP1 and AMP2 and vice versa

• Further mixing is taking place at the isolators

Tx

Rx

DUT

Tx

Rx

“Blocker” Source

Spectrum Analyzer

TX1

TX2

34

Triple Beat Filter Based - Phase 2

Notes:

• Hi Q ceramic puck filter can provide ~40dB rejection

• Adding isolators can increase the isolation to ~60dB

• Carriers are terminated after passing through the DUT

• Depending on “Jammer” power level, this setup should be able to provide a good base line

DUT

Spectrum Analyzer

f2

f1

f2

IM

f1+f2

f3

f1

f3

IM in Rx Band = f3-(f2-f1) & f3+(f2-f1)

35

Triple Beat Filter Based - Phase 3

• The Band-Pass filter is passed f3 and rejects the IMD products by 40dB.

• The Band-Stop filter passes the IMD products and rejects f3 by 40dB.

• The Band-Pass filter (or Band-Stop filter) can be terminated, providing a broadband match to common port.

Introducing the narrow band BP/BS Duplexer

2MHz

36

Triple Beat Filter Based - Phase 4

Notes:

• Units enclosed in dashed line are all integrated

• Number of external connections and jumpers kept to a minimum

DUT

Spectrum Analyzer

f2

f1

f2

IM

f1+f2

f3

f1

f3

37

The Road Map to Test Rack System

ATE Integrations • Supports automated production testing of wireless systems and semiconductor

product families covering all LTE bands • Provides emission monitoring while maintaining a good impedance match with the

device under test (DUT) • Can be used to measure IM products and NF and for Triple Beat tests

38

Switch Matrix

Modular Architecture

flexibility

reconfigurable

expandable

Compact Structure

reduce 10X10 rack space

from 4U to 3U

Trouble-free Maintenance

field serviceable

field upgradable

Removable Power Supply

easy access

redundant power

supplies available

Fast Switching Time

< 50ms

Interface Options

Ethernet (TCP/IP), HTTP

Server, LabVIEW-based

Web Services, RS-232,

USB, GPIB, ...

Mounting Brackets for Switches

Power Module (Mounts Vertically for 3U and 4U

Enclosures)

2U Model

Next Generation Matrix

39

Custom Solutions

Low PIM Test Station for….

Cell Phone Tester for…..

40

Coaxial Switch - Data

41

The Road Map to Test Rack System (cont.)

42

Interface Options

Most switchable RF devices provide a combination of remote and local interfaces. A typical unit is equipped with one or two of the following options:

o SNMP SNMP v.1 SNMP v.3 (coming soon)

o LabVIEW-based Web Services o GPIB o Ethernet (Built-in Web Server) o USB o RS-232 o CAN-bus

-- load the Lua VISA wrapper

require "visa"

-- open connection to equipment

if interface == "GPIB" then

-- use GPIB interface 0 at address 16

c = visa.open "GPIB0::16::INSTR"

else if interface == "SERIAL" then

-- use serial (RS-232, RS-485, etc) interface 1

c = visa.open "ASRL1::INSTR"

else if interface == "TCP" then

-- use TCP/IP over interface 0

c = visa.open "TCPIP0::192.168.1.5::7::SOCKET"

end

-- set switch 1 to position 2

c:write "CT1.2"

43

Further questions on this topic can be addressed to the author, Rafi Hershtig, at rhershtig@klmicrowave.com.

www.klmicrowave.com

44

Further questions on this topic can be addressed to the author, Rafi Hershtig, at rhershtig@klmicrowave.com.

www.klmicrowave.com