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SO/J 020152 - J 5930

An L-Band, LTCC Frequency Doubler UsingEmbedded Lumped Element Filters

Richard HurleySand ia National Labsrbhurle@sandia .gov

Sandia is a m ultiprogram laboratory operated by Sandia Corporation, a Lockheed M artin Company,for the United States Department of Energy under contract DE-AC0 4-94AL8500 0 . SandiaNationalLaboratories

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Background Application- Airborne S ynthetic ApertureRadar (SAR)

Fine Resolution = Large % RF Bandwidth Requires Frequency Multiplication

Go al- Sm aller UAVs 6U VME = 3U VME 1/6 Weight Red uction 1/3 Volume Redu ction Reduce Card Count

Investigate LTCC F or RF M iniaturization Case Study : L-Band Frequency Multiplier Demons trate Size Reduction in Practical Circuit Evaluate Performance Identify Limitations Understand Design/Fabrication/Cost for LTCC

SandiaNationalLaboratories

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L-Band Frequency Multiplier Stage Original

Single Layer Filter Large -0 .6"x 6 .0 " Original

MAAM12000-A1 HMC187MS83d B X2

3500 MHz 2500 MHz -17dBm-9dBm '

EMBEDDED FILTER AND PAD i3d B : 3d B' LPF HPF OUTPUT

-20dBINPUT-2dBm

3d B

19d B14dBm

RF DiscreteLTCC

LTCC Stacked HPF/LPF In Substrate Buried RF Attenuator Part Selection/Layout Matches Filter 12 Tape Layers/'0.1" -0.6"x0 .45"

LTCC 4 ` EMBEDDEDSTACKMULTLAYERFILTERBias/CNTRL---- P -

S a n d i aN a t i o n a lL a b o r a t o r i e s

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Embedded Filters Lumped

Topology Elliptic LPF /All-Pole HPF IncorporateParasitics # Of Layers =Varies Series/Shunt C Ratio Favor LargeCap Values

(C A/h) Sidewalls ForShielding

BottomGroundPlane(Top NotShown)

5 Tape Layers, -0.038"Surface : 0 .27"x0 .23"

6 tape layers, -0 .045"Surface : 0 .26"x0 .21"

T To.RA.r 1 C PMM

BOTTOM ONN

r o R O N O (N O r S H O W N )

BOTTOM GNP

C _SHUNT I_SHUNTT

C SER e

1 C-

SHUNTIC SHUNTR L, SER

3)


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Results Conversion Loss as Expected Slight Filter Shift Acceptable Spurious Isolation Issues

Input-1 1

-10016

Output

2500 2750 3000 3250 3500Input Frequency (MHz) 0 3000 6000

Frequency (MHz)


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Filter Shift Cross-SectionMeasurements

- Nom inal Stack Height- Tape Spacing Less ThanExpected (-5%)- Other Tolerances O K

Full Fired- Expect DielectricConstant Increase(5 .9= 6 .2)

Consistent Within andBetween Fabrications

- - - - - Measured LPFIHPF (Includes Pad and CKT Losses)Model: N ominal Tape Layer, er=5 .9, H=7 .4Model: Compressed, Full Fired, er=6 .2, H=7 .0

0

1 2 3 4 5 6Frequency (GHz)

SandiaNationallaboratories

0 0 000 000 0 0 0000 00000- 00

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RepeatabilityMultiplier vs Test Circuits

Multiplier TC #1 C #2 T C #3 T C #4

Includes 3 dBpad and LPF

-501 0 0 0 20 0 0 3 0 0 0 4000 5 000

Freq (MHz) HPF Com mon Between Test Circuit & M ultiplier Mo nitored 3dB Point Tracking Good W ithin! Between Fabs

S a n d i aN a t i o n a ll a b o r a t o r i e s

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Isolation Adequate for Low Frequency Higher Frequencies Degraded Surface Radiation Dominates Field Leaks Through GND

Input Launch Doubler Output Launch

4[9/41:11 .0009e+0059 .$833e+0049 .16674+0048 . 73004 .0040 .33334+0047 .9167e.0047 .50004+0047 .08334+0046 .66674+0046 .2500440045 .83334+0045 .4167e+0045 .00004+0044 .50334+0044 .16674+0043 .75004+0043 .33334+0042 .91674+0042 .50004+0042 .08334+0041 .66674+0041 .25004+0048 .33344+0034 .16684+0031 .21644-001

0FundamentalBand

-800 2 .5 5 7 .5 10


FREQUENCY (GHz)

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Isolation Improvem ent?

Measured/ModeledSimple Test Structure Suggests Improvements

- Locally Solid10 19 - 2nd Offset GND Plane

Freq (G 1-k)op Signal7.4 milsGND Sheet l3 .7 milsND Sheet 2 (if used)7 .4 mils Bottom Signal- 1-5o-75 . Measured,1 Plane Test CKT Simulated, 1 PlaneSinxiated, 2 Planes wMas Two Offset GNDs


Single Layer GND

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Summary

W ideband L-Band LTCC Multiplier Stage Order of M agnitude Footprint Reduction Embedded Filter Feasible Buried Resistors Adequate

Observations Careful EM Modeling/Design Required Repeatable If Using Sam e Process Broken Ground Plane Isolation Major Concern at Higher

Frequencies Future Work Higher Frequencies Isolation Issues

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