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H I G H P E R F O R t N N C E M I L L I M E T E R WAV E RE CE IV E RA N D T R A N S M I T T E R COMPONENT DEVELOPMEMY

Jsrg E . RalieTRW Ddense and Space Systems GroupRedondo Beach, Cal i o r n i a 90278

A b s t r a c t-

Thi s p a p e r descri t e s th e s uc ce ss fu l a ~ p l a-t i s n o f a dv an ce d d e si g n t e ch n i q ue s t o m i l l i m e t e rwave f r equenc ies , w h ic h have r e s u l te d i n ex c ep t i on a lha rdw ar e pe r fo r manc e. Top i cs i nc lud e s o l d s t a t epower aqpl if r s , upc onv e r te r s , downconverters ,c i r c u l a t o r s , m i x e r s , h y b r i d s , a n d f i 1 e r s .I n t r o d u c t i o n

The need fo r dev e lop ing c r i t i c a l c omponentt e ch n o lo g y i n t h e EH F band i s p a r t i c u l a r l y u nd er-s c o r ed by the r equ i r emen ts o f h iqh pe r fo r manc es ys tems and subsy stems w i th a pp l i c a t i o ns i n thea re a s o f s a t e l 1i e c om un ic a t i o ns , advanced e lec -t r on ic war fa re , and radar . Severa l bands haveb een i d e n t i f i e d su ch as 30 t o 40 GHz , 55 t o 6 5 GHz,and 90 t o 100 GHz, where a stronq component capa-b i i t y i s e s s e n t i a l .

TRW's development emphasis has beer 00 h i g hperformance, broadband components. Th is paperdes c r i bes the s uc c es s fu l app l i a t i o n o f a dva nc eddes ign tec hn iques t o m i l l im e t e r wave f r equenc ies ,,+hich have resul t e d i n ex c ep t i on a l ha rdw a re pe r -formance. These s t a t e - o f - t he -a r t m i 11 me t e r wavecomponents have been genera l l y des igned f o r sa te l -1i e a pp l i c a t i ons and fea tu r e w ideband ope r a t i o n i no r d e r t o p r o v i d e maximum f l e x i b i l i t y f o r a v a r i e t yof appl i a t i o ns , such as spread spectrum comuni-c a t i o ns , f r equenc y . hopping r ada r s , h i qh da ta r a teana loq and d i q i t a l sys tems and broadband rad iom etersTransmi t er Com~onens

F i q u r e 1. S- t .o -Ka-Rand U ~ c o n v e r t e rw i t h 2 GHz of BandwidthKa-Band Amp1 i f i e r

T h i s n e q a t i v e r e s i s t a n c e amp1 i f i e r i s c o n f i q u r e da s a t h r e e - s t a q e d e si q n , p r o v i d i n q 23 dB of qainw i t h a n o u t p u t p ow er o f 0.5 Watt. T h e a m p l i f i e r ,show n i n F iqu r e 2 t o q e t h e r w i t h m e a s u r e d d a t a , ex-h ib i s f 1a t b r oadband r espons e ov e r 2 G H z of band-w i d t h, w i t h e x c e l l e n t i n p u t- o u tp u t c h a r a c t e r i s t i c s .I n t h e d ev el op m en t o f t h i s a m p l i f i e r , t h e f o l l o w i n gdesiqn approach was used:S t a t e - o f - t h e - a r t p e rf or m an ce o f s e v e ra l ke yt r ans mi t te r c omponen ts IS descr ibed.

Broadband Va rac to r Doubl e r /U pco nve r te rT h i s component was designed as an upper s ids -Sand d o u bl e r / u p c o n v e r t e r c ap a bl e o f e f f i c i e n t l yu p c o n v e r t i n g a 2 GHz wide S-band s i gn a l t o Ka-5and.Th i s un i t repr ese nts two compunents, a f requencydoub le r and an upco nver te r combined i n t o one - u s i n ga Ku-band pump ( a t app r ox ima te l y 17 .5 GHz) dn S-band

s i g n a l ( 2 t o 4 GHZ) i s upc onv er ted t o a Ka-band ou t -p u t a t 37 t o 39 GHz . This component i s shown i nF i g u r e 1. The th ree p or t s , wavequ ide ou tp u t andw mp, as w e l l as the c oax ia l I F i n p u t p o r t , a r ec l e a r l y v i s i b l e . T h i s u n i t e x h i b i t s a 1 dB band-w i d t h o v e r 2 GHz, w i t h an I F t o RF c onv e r s ion l os sof zero t o l e s s t h a n 3 dB and an RF c onv e r s ione f f i c i e n c y o f 1 1 dB, i n c lu d i n g i s o l a t o r and f i l t e rlosses . The RF ou t ou t pow er i s 5 mu.

c a re f ul c h a r a c t e r i z a t i o n ( a t b o t h sm a l land l a r q e s i q n a l l e v e l s ) o f t h e p ac ka ge dGaAs ava lanc he diodes. Usin q a ne tw o r kana l y z e r , t he d iode te r m ina l impedance i sm ea su re d a s a f u n c t i o n o f d r i v e l e v e l , b i a sl e v e l a n d f r e q u e n c yc o n t r o l and p r e d i c t i o n , t h ro u gh c i r c u i tmodel i n q and compu te r a i d ed des ian , s f t heimpedance s een by the d iode i n th e ba s i cw a ve q ui de c i r c u i t , as w e l l a s t h e i m ~ e d a n c eo f the ex t e r na l b roadband ma t c h i nq network.t he d e t a i l e d o v e r a l l c h a r a c t e r i z a t i o n o ft h e a m p l i f i e r .

L l h i l e t h i s a n p ro a ch i s t y p i c a l l y e m olo ye d i n t h edes iqn o f h i q h oe r fo r manc e amp1 i f i e r s a t X-band o rb el ow , a nd p a r t i c u l a r 1 w i t h c o a x i a l t y p e c i r c u i t s ,i n a q qr eq at e i t has c o t p r e v io us l y been employ ed a tKa-band.

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No t u n i n g screws are used i n t h e a m u l i f i e r , nor i s

F i g u r e 3. 5-s taqe , ! ? -wa t t , 37 GHzS o l i d S t a t e A m l i f i e rWecei v e r Compenentr

r e c e l v e s s i d e , h ioh n e r feen deve loped at b o t h Yabroadband T I rer-5, f o r ex-i d t h waveouide i $ - i x p p 1 sd e s c r ~ed .(b Ir a c o n v e n t i o n a l w a v e a ~ ' ? ~a r e r , t P e u l t ~ n a : ~u s ab le b a nd w id th i s l i m i t e d b v t h e o o e r a t i n ~ r c -F i q u r e 2 . ( a ) Three S taqe Amp1 i f i e r quency ranae o f t h e wavequ id? used. GeneralSv,( b ) A m p l i f i e r - I n p u t - O u t o u t m i x e r p e r f o m a n c f decarades c o n s i desab l v w h w m e r -C h a r a ct e r i s t i c s a t i n q w i t 4 a b d ~ d t b exceed ina 70 t n 1 s perrent ,a nd be co rn in a t o t a l l y u n u s a b l e when o o e r a t i n ~w a r

I n a d d i t i o n t o the amp1 i f e r d e s c r i b e d a b ovea v a r i e t y s f mi 11 me te r wave ava lanch e amp1 i f i e r shave been deve loped , bo th a t 35 t o 46 GHz and 55t o 65 GHz r ange , as s a r i ze d i n T a bl e 1. Thea m p l i f i e r s u se S i s in q l e d r i f t and d o u b l e d r i f td i o d e s a n d o p e r a t e i n t h e n e g a t i v e r e s i s t a n c e a n di n j e c t i o n B o c k ~ dmode. Emphas is i s on r e l i a b l eo p e r a t i o n a t r e a so n ab l e j u n c t i o n t e mp e ra tu r es .S t a t e - o f - t h e - a r t ~ e r f o n n a n c ewas a c h i ev e d a t K a -and V -b an d. A t V -b an d, t h i s u n i t e x h i b i t s 6.4 p e r -ed e f f i c i e n c y w i t h a j u n c t i o n t e m p -e r a tu r e r i s e o f 1 7 5 " C , a s w e l l a s a n i n j e c t i o nl oc ke d a m p l i f i e r w i t h 1 .3 GHr o f l o c k i n q b a n d w i d t ha t a g a i n l e v e l o f 23 dB , f o r a v o l t a q e q a i n - b a n d -w i d th p r o d u ct o f 18 6th.Aoped. *v i de sr e s i s tNove 1

s t a g e st y p i c a

t Ka-band, a 5T h i s 5 - s t a g e33 dB o f g a i nance as w e l l ab r oa d b an d c i cand p r o v i d e h1 i n s e r t i o n l o

Watt power am p l i f i e r was d ~ v e l -u n i t , show n i n F i q ~ r e , p r o -a t 3 7 GHr and uses neqa t iwes i n i e c t i m l o c k ed a r up l i f i er s.u l a t o r s c o u p l e the individuali g h i n t e r s t a g e is07 a t i c n w i t hs s l e v e l s o f 0.1 dB p e r ~ a t h .

* 1 h i s work was suppor ted by t h e i r F o r c e A v i o n i c sL a b o r a t o r y , W r i g h t - P a t t e r s o n AFE, Ohio , underCont rac t F33615-74-C-1051.

t h e w avequide c u t ~ f f ~ u a e n c v ecause of w n a c c a t -a b l y h ish l o s s e s . Here wc d e s c r i b e a new m i x e rd e s i q n w h ic h u t i l i z e s a c r o s s b a r mixer c o n f i c u r a t i me r w i t h a d o u b l e - s i d o e wavenuide m u n t . T h ei s c a p a b l e o f o o e s a t i o n f r o mw i t h e x c e l l e n t p e rf or m an c e. qvera t i n q f r e q u e n c y ranqe, t y o i c a l c o n v e r s i o n l o s s o f5 t o 5.6 d 9 was m ~ a s u r ~ d , i t h a m i v j i r n u ~o f 4 .2 dB .a r i zes t t s e w r f o m a n c e .

The o c t ~ v e andwidth m i x e r c o n s i s t s o f a doub l e -r - idqe wavequide mount, a r i oe d w a v e w i d e - b - c o a ~ i a l1 line t r a n s i t i o n , t w o S c h o t t k y b a r r i e r d il o w pass f i t e r . T h e double-ridae waveaui r '3 m o u n ta l s o s e r v e s as tne b a e k sh o r t h o l s i n a o f the v i x e rmount. The m e c h a n ic a l c o n f o u r a t i en o f t h e o c t a v ebandwidth r n i x ~ r s shgwn i n F i q u r e 9. T h e h e a r to f t h e m i x e r i s a p a i r of lo w n o i s e C c h o tt k v b a r v l e res a c r o s s t h e b r o a d w a l ; ~o fne o f t h e e l e c t r o d e c o f eachd i o d e c o n n e c t s t o a w t a l c ro ss ba r whic4 serves a ca m ec ha nic al s u p ~ o r t o r Ebe d i o d e s and a l s o as at r a n s m i s s i o n l i n e f o r t h e i n c o v i n ~ R Dower and theI F o u t p u t s i q n a l n . I n a c t u d l o p e r a t i o n , t h e R Fs i q n a l i s fe d d i r e c t l y t o the r i d a e d w a v eq u id e v i aa r id cr ed w av eq uid e- t o - c o ~ x i a l r a n s i t i m i and caoa-

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Table 1. Avalanche Amp1 i f i e r Per formance Sumnary

OutputFrequency Power E f f i c i enc y AT Gain Bandwir i t l r( G W (mw ( Pe r c en t ) (OJC) (dB) (GHz) G r BW37 200 3.5 175 1 3 2 .6 ( 2 - s tage ) N eqa t i v e R es i s tanc e35 500 4.0 200 23 2.0 (3 -s tage ) N egat ive Res is t ance3 7 300 7.0 180 25 0.2 6.0 GHz I n j e c t i o n L o c k e d37 5W 8.0 250 7 0.7 1.6GHz I n j e c t i o n L o c k e d64 150 6. 4 175 12 1 O 4.0 GHz Ne qat i ve Resi sta nc e

55-65 100-200 5.0-7.0 200 23 1.3 1 8. 0G H z I n j e c t i o n L o c k e d

Tab le 2. Broadband Mixer PerformanceParameter k reque ncv Ranqe Perfo rman ce

I 22-40 GH zConve rsion Loss 20-40 GHz 4.3 -5.8 dR4.2-6.5 dB22-40 GHzDS B Noise F ig ure * 20-40 GHz 4.8-5.7 dB4.8-7.0 d9- - - --*Mixer f i xe d tuned a t 35 GHz, measured a t 750 MHzI F , n o i s e f i q u r e o f I F a m p l i f i e r i s 1.5 dB.

c i t i v e l y c ou p le d t o t h e d io d es . The I F o u t p u t i sex t r ac ted f r om the oppos i te end o f the c r os s ba rv i a a mi cr ow av e i n t e q r a t e d c i r c u i t lo wp as s f i l e r(LP F ) . The LPF i s u s ed t o p r ev e n t LO power l e a k i n gt o th e I F o u t p u t . E l e c t r i c a l l y , t h e two m i x er d i o -des ar e c onnec ted i n s e r i es w i th r es pec t to the RFs i q n al and i n p a r a l l e l w i t h t he I F ou tpu t . Th i snrov ides a h i g b e r i mn ed an ce l e v e l t o t h e RF s i q n a land a lower impedance ieve l to t h e I F s iqna l thana s in g l e d iode m ix e r . The r e fo re , an i nhe r e n t i m -pedance match co nd i t io n fo r 90t h the RF and I F s i q -na l s i s ach ieved f o r b roadband per fo rmance. I na d d i t i o n , t h e r e l a t i v e l y l o w im peb an ce o f t h er idg ed waveguide f u r t h e r improves i rnpeda~ice matc hino f the m ix e r d i odes. Th i s r e s u l t s i n an ex t r eme lybroadband mix er des ign w i th un i fo rm1 low lossesover an operat ing frequency ranqe exceeding anoctave bandwidth.

Figure 4. Octave bandwidth K-band cros sba r mixer ,shown about tw ice accua l s ize .

I n t h e are a o f m i l l i m e t e r wave i n t e q r a t e dc i r c u i t s , a 34 t o 38 GHz downconverter was developed.T h i s u n i t , shown i n F i g u r e 5, f e a t u r e s a f u l l y i n t e -g r a t e d Gunn l o c a l o s c i l l a t o r and beam lead GaAsS c h o t t k y m ix e r d i od e s , a nd i s 1 c u b i c i n c h i n s i z e .T h i s s ap ph i r e s u b s t r a t e m i x e r e x h i b i t s a c onv e r s ionlo ss o f 5 dR a t 37.6 GHz and less than 7 dB acrosst h e 34 t o 3 8 GHz band. When measured i n co n ju nc t io nw i t h a 4 t o fi GHz I F a m p l i f i e r ( 4 . 5 dB t y p i c a ln o i s e f i g ~ ~ r c, the measured SS B o v e r a l l r e c e i v e rnofse f i q u re i s 11 dR t y p i c a l ,

F i g u r e 5. 34 t o 3 8 GHz integratedDownconverter

Passive Components-A number o f key pass ive components are requiredi n dev e l op i nq c omp le te RF t ra n sm i t t e r a nd r e c e i v e rs ub sv st em s, i n c l u d i n g c i r c u l a t o r s , v a r i o u s t y p e s o ff i 1 e r s , t r a n s i t i ons , impedance transformers, and3 dR hy b r i ds . Tab ie 3 sumnar i zes th e per form anceo f a r e r r e s e ~ ~ t a t i v er o s s s e c t i o n o f the components.The unique comnon fe a t u re s or the components aret h a t t he y a r e a l l f i x e d tu ne d. A l l e x ce p t t h e Ka-band c i c u t a t o r a re e l ~ c t r o f o r m e d . ~ ~ n p h a s i snd e s i g n was p l a c e d on t r u l y h i g h ~ e r f o r m a n c e nd r e -l i a b i l i t y - bot h were ach ieved.

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T a b l e 3. Performance Sumnary o t t l e c t r o -formed Passi e ComponentsCenter Insert IanFmqwncy Band- Loss IsolationCanponent (Wz) w i d * + (dB) "B) VSYR

3 d8 Short Slot 30-37 4 6MzHybrid 55-65 8 Wz

HIgh Pass 30-38 ---fl UTS %-65 -- -

C l cu lr t o o

.I Wz b e l a &sign pass frequency-2 Wz b e l w design pass frequency

C i r c u l a t o r sT h e w a v e g u i d e c i r c u l a t o r c r i q n d e s c ri b e d hereuses a d o u bl e t u r n s t l l e j u n c t i m m d o p t i m a l l y com-b i nes RF b r oa d b an d a nd l o w - l o s ~ e rf or m a nc e , D a r t ss im p1 c i y , r ug g ed n es s, a nd t e m p e r a t u r e s t a b i 1i yi n one u n i t . S p e c i f i c a l l y , t h e f o l l o w in q c h a r ac t e r-i s t i c s a pp ly :1 ) No e p o x i e s o r a d h e s i v es o f a ny k i n d a r eused si n c e a l l c y l i n d r i c a l p a r t s ar e s e l f -i nd ex ing . Mechani ca l r uggedness i sa c h i e v e d by s ta ck in g t h e f i v e c y l i n d r i c a lp i e c e p a r t s (se ptu m, t w o f e r r i t a , andt w o d i e 1 e c t r i c c o u p ?i q s p a c e rs ) i n s i d e aa t h i n d i e l e c t r i c s le ev e. The s l e e ve i s

i n d e x e d t o t h e h o u s i n g v i a a r e c e s s inth e m e t a l 1 c m a t c h i n g t r a n s fo r m e r s . T h i sa r rangement obv ia tes t h e n ee d f o r e p o x ie so r g l u e s a nd a d d i t i o n a l l y a ss ur es l o wl o s s . A photograp h of assembled Ka-bands i n g l e - j u n c t i o n c i r c u l a t o r s i s shown i nF i g u r e 6, t o g e t h e r w i h r e p r e s e n t a t i v eper forman ce data. The desisn has beepe x t e ~ d e d o 5 j u n c t i o n s , as w e l l a s t oa1 1 f w q r ~ e n c ybands f r o m 7 t o 40 GHzw i t h comparable p~ +- formance. The re su l ti s a r u q ge d m e c ha n ic a l d e s i g n s u i t a b l ef o r s p a c e a p p l i c a t i o n s .2 ) T h cn n al s t a b i l i t y was a c h i e v e d by u se o f

f e r r i t e m a t e r i a l ( TT 2-1 11 ) w i t h l o w ?nMSv e r s u s t e m p e r a t u r e v a r i a t i o n , by j u n c t i o nd e s i g n a l l ow i n g o p e r a t io n w i t h f e r r i t e sb i a s e d w e l l i n t o s a t u r a t i o n an d by u se o fh i g h q ua 1i y , r a re -ear t n pe rmanen t magne t s .

F i q u r e 6. T y p i c a l C i r c u l a t o r P e r f o r m a n c e3 dR Hybrids

A r e c e n t e x t e n s i q n o f our n i l l i m e t e r wave f i x e dt u n e d hybrid development resul te ; f . i n a 4 - h y b r i d , 4-way power d j v ide r / camb i ner c i r c u t i r 3 t nq ra ted andf a b r ic a t e d i n one u n i t , The pal ished aluminum man-d r e l , show n i n t h e b a ck q r o un d of F i q u r e 7, c o n s t i -t u t e s t h e b a s i c o a r t , w 9 i c h i s m a ch in e d an d p o l i s h e dt o t h e i n t e r n a l d im e ns io ns o f t h e C ~ t e q r a t e d y b r idassembly. Copper i s subsequent1 v e l e c t r o ~ lt e d o n t ot h e m a n d r el f l e f t i n f i q u r e 7) . F l m q e s a r e a t ta c he da n d f i n i s h m a c hi n n q t a k e s p1 ace w i t h the mandrel i nplac e. The man dre l i s subsequen t l y etched away t oproduce t he conoonep t i n f i n a l f o m ( r i g h t f o reg roundi n F iq u r e 7 ) w i t h a h i g h q u a l i t y i n n e r s u rf ac e f i n is b .

3 ) Two t u r n s t i l e j u n c t i o n s s e p a ra t e d by t h i nr e f l e c t i n g s e ptS tm a l l o w u se o " s t an d a r d -he igh t wavegu ide .F i g u r e 7. Four-Way Hy b r i d Powern i i der and ReeomlbinerC i r c u i t

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b i ters

Numerous f i x e d tun ed bandpass and highpassf i l t e r s (n o t u n ~ n g crews) have been fa b r i c a t ed i nth e 26 t o 65 GYz frequency range. A r e p r e s e n t a t i v ec ro ss s e c t i o n o f b andpass f i l t e r s i s s hown i nF i g u r e 8. B o t h i n d u c t i v e p c s t and c a p a c i t i v e v an ety pe f i l t e r s h ave been developed , w i t h t he f i x e dtuned capabi l y encompassi ng f i e r bandwi d thsfrom 10 Je rcen t t o abou t 0.5 pe rcen t , w i t h up t o5 s e c t i o n ? . T he c a l c u l a t e d d e s i g n c e n t e r f r e q u e nc ycan be rou t i ne ' y met e x p e r i m e n t a l ly t o w i t h i n 0.3percent. Measured VSWR i s t y p i c a l l y 1 .2 and o f t e nas low as 1,05 ov er th e passband. Ty pi ca l Q ' s a r e3000 t o 3500 i n Ka-band and 1800 t o 2000 i n t h e 55t o 6 5 GHz f requency ranqe.

Th e h iqhpass f i e r s i n c o r p o r a t e a msdi f ede x p o n e nt ia l t a o e r d e s iq n t h a t c o r r e c t s f o r t h ee l e c t r i ca7 l e n g t h v a r i a t i t m i n t ro d u c e d by t h e t a p e rbecsuse of a c o n t i n u o u s l y c h a n q in g g u i d e w a v e l en q t ha nd i n c o r p o r a te s t h i s c ha ng e i n t o t h e o h y s i c a ldimensions. T y p ic a l r e s u l t s , t o ge th e r w i t h t h ehardware, are shown i n F i q u r e 9 , Bv c o m ~ a r i s o nw i t h o t h e r t ec h n iq u es , t h e c o r r e c t e d e x p o n e n ti a1t a p e r re s u l t s i n a s te e pe r s k i r t r e j e c t i o n as w e l las rneduced VSWR i r r e w l a r i t y a t t h e s k i r t e d ~ e .

F i q u r e 9. H iq hp a ss F i l e r a ndF i 1 e r Performance

F i g u r e 8. Asso rted Fix ed TunedWaveguide Bandpas5F i 1 t e r s