Now-bnd Receive Rdio chiecues
l l l l l Double-convesion single-qud Supeheodyne Diec-convesion Single-convesion singlequd, hoodyne, Zeo- Double-convesion double-qud Low- Refeences
Down-convesion; The ige poble: Desied signl LN ~ Blocke ige 3 Blocke level cn be odes of gniude lge hn desied signl f no blocke pesen, you sill fold he ige noise ~3dB SNR hi Feq Feq cos cos cos cos fe he lowpss file following ixe, he oupu is: oupu cos cos cos cos cos
The Supeheodyne chiecue: 4 OFF chip ge file file Pssive BPF LN The choice of he fequency: Relively low equies vey high-q ige file o povide decen ejecion he ige fequency, which nsles ino highe file pssbnd loss nd so highe Rx NF, nd highe cos. Relively high esuls in oe cuen consupion fo he subsequen sge cicuis, especilly he VG. ypicl fequency is 00-00MHz. One of he os obus nd low-cuen eceive chiecues equies sevel bulky off-chip coponens ~ ge file eoves boh blocke nd noise fo ige befoe downconvesion
plnning in Supehe chiecue: 5 OFF chip ge file file VG PLL ~ VCO Pssive BPF LN Q PLL ~ VCO Two sepe VCO s nd synhesizes e usully needed. The is usully fixed, while he is vible o down conve he desied signl o fll wihin he SW file bndwidh. The soluion is 3-4 chip soluion wih hee exenl SW files. should neve be de close o be n inege uliple of fo ny chnnel. The N h honic of he fixed could lek ino ixe cusing unwned ineod. blocke f n leks o ixe n
The ½ poble in supehe chiecue: blocke Supehe Rx 6 0 ½ Le us ssue hee is n undesied blocke hlf wy beween he desied signl nd he, s shown. Thee e wo echnis his blocke cn fold ono he desied bnd. The fis if he fon-end hs song second ode non-lineiy. ½ cos 0.5 cos blocke blocke blocke f he hs lso lge second ode coponen, he esul would be coponen of he blocke folding ono he bnd, igh on op of he desied bnd cos cos cos... blocke blocke Noe h he blocke folds wih wice is signl bndwidh due o he sque.
7 0 0 ½ ½ The second ens by which he blocke cn fold ono he desied bnd if he sge hs song second ode nonlineiy. cos0.5 cos bloc ke blocke blocke Noe gin hee h he blocke folds wih wice is signl bndwidh due o he sque. is heefoe n exeely ipon decision o chose he fequency so h hee is no song hlf blocke nywhee in he syse, o if hee is ny, he desied second ode nonlineiy of he eceive is cefully clculed.
Supehe; Dul convesion single-qud: 8 OFF chip ge file file VG ~ Pssive BPF LN Q Disdvnges: ~ equies sevel bulky off-chip SW files. genelly wo diffeen synhesizes e equied hee-chip soluion:, nd synhesize dvnges: obus. high-dynic nge SW files elxes h of he cive cicuis, dsiclly educing hei equied dynic nge.. Esie o design low cuen consupion <0 fo WCDM
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0 ge suppession by pope phsing Hilbe chiecue: Pssive BPF LN 90 ~ 90 Σ B C C C C B cos cos cos cos cos cos sin sin sin sin sin cos cos cos cos cos cos cos ' file
Hilbe chiecue: Disdvnges: equies exeely good phse nd gin ching. Only ~35dB of ige ejecion is possible wihou iing o uning. This is no enough in soe pplicions whee he ige is 60dB highe hn he desied signl. consues oe cuen.. bi powe hungy dvnges: eliines he exenl ige SW file. offes bee inegion, bu sill second chip is needed fo finl down convesion 45 Pssive BPF LN 45 35 ~ Σ D file odified bee cking chiecue B 35 C
pc of gin nd phse iblnce on ige ejecion Le us ssue h signls nd Q expeience non-idenicl gin. Fuheoe, he phse is no excly qudue nd hs soe phse eo. To find he ipc of boh gin nd phse iblnce on ige ejecion, le us e-wie he equions s follows:
ge ejecion equion The ige ejecion in db cn hen be wien s: is in d Fo sll : 3 Fo sll nd, he RR cn be ppoxied o: degees 0log db
Double convesion double qud chiecue: C 4 ige Pssive BPF Pssive BPF LN 90 90 B + ige + signl Fis D F E + Σ - + Σ + Q ~ N second The dul convesion double qud chiecue hs he dvnge of de-sensiizing he eceive o gin nd phse iblnce of nd Q phs. Mke sue nd vlues e chosen so ige fo fis down-convesion flls ou of bnd ejeced by exenl SW pssive BP file.
5 E D Q F C B F B E D C B sin cos cos cos sin Lowpss sin sin cos Lowpss sin sin sin Lowpss cos cos cos Lowpss sin sin sin Lowpss cos cos cos Lowpss cos cos The bove nlysis ssues idel qudue geneion. Bu wh if hee e soe phse eos?
6 E D Q F C B F B E D C B sin cos cos cos sin Lowpss sin sin cos Lowpss sin sin sin Lowpss cos cos cos Lowpss sin sin sin Lowpss cos cos cos Lowpss cos cos gin eo nlysis: s seen he gin isch eo ges educed due o he poduc of wo sll vlues. ypicl gin eo of such chiecue cn be s good s 0.dB -sig.5ghz.
Phse eo nlysis: cos Lowpss cos B Lowpss sin C Lowpsscos D Lowpsssin E LowpssB cos F LowpssB sin cos cos cos sin sin cos cos sin sin sin sin cos cos Cn you deive he finl esul? Hoewok!!! 7
The diec convesion Zeo- chiecue: Why no eliine he copleely nd ix he signl wih n he exc se fequency s he desied signl? 8 in Pssive BPF LN 90 ~ Q in LPF fo Q LPF cos cos 0.5 cos in 0 sin 0.5 sin in No ige nyoe wih pefec /Q ching! Wh if hee is /Q isch in diec-convesion? Cn hee sill be n ige?
pc of /Q isch in diec-convesion chiecue: in LPF fo cos Q LPF in cos, nd finie /Q gin nd phse isch of nd, especively in sin 0.5 0.5 coscos sinsin sincos cossin /Q coss lk ge fo se desied signl coposed of Q signl leking ino nd signl leking ino Q /Q coss lk. This esuls in degdion of SNR. Since he ige coes fo he signl iself, he ige ejecion equieen is llevied se by ge SNR of he eceive 9 -f f 0 fe ixe feq Negive feq ige lis
Pobles wih Zeo- convesion: 0. self ixing: Pssive BPF LN 90 ~ Vies wih nenn VSWR B Q p cos p p cos Dynic DC offse self ixing degdes DC-offse in diec-convesion eceive. Sic one cn be clibed ou bu dynic one ie vying cn be poble
. DC offse: 60dB gin Pssive BPF LN 90 ~ Q V DC offse V DC offse Since he signl is conveed down o DC, he signl ph pos ixe is DC coupled. This kes sligh DC offse o ppe s vols nd os likely o sue he subsequen bsebnd cicuiy. C coupling is expensive since lge C coupling cps should be used o chieve low highpss cone <khz. lso ny offse nsiens due o gin swiching will esul in lge DC nsien h will ke long ie few s fo khz cone o sele. Two coon echniques fo DC offse eovl: nlog sevo loops B digil DCoffse clibions
3. Sensiiviy o second ode disoion P: Le us ssue wo jes seped by Δf s s s s cos cos cos cos cos cos cos cn be seen hn he second ode disoion in he eceive esuls in wo low fequency disoion h folds ino he desied signl fe being downconveed ound DC:. The bsebnd odulion ound he je cie ges folded ino bsebnd wih wice bndwidh. The wo jes be gins ech ohe nd poduce coponen only Δf wy fo DC. f Δf is close enough, he M disoion will fll ino he desied signl bnd. Even if Δf does no fll wihin he desied signl bnd, i cn be close enough o clip he enie eceive if i does no ge fileed ou popely befoe i eches he VG. Noe h s cn be siple CW je in soe syses
4. Sensiiviy o /f flicke noise noise densiy 00ni /f, slope 0dB/dec 3 Since he down conveed signl is ceneed ound DC low fequency, he device /f noise becoes ipon. Fo exple, if he /f noise cone of GSM eceive is hlf he desied signl bndwidh s shown bove, he degdion his could cuse o he effecive noise is ssuing noise inegion sing khz: n ve n ve 00k 00kHz khz df f 00kHz 00kHz 00k ln b 00k k ni bdf ; khz whee k 00n 00k 00k 00k.5 00kb 6.5n 00kHz i ; b n This is vey chllenging sk in CMOS design given he elively lge /f noise cone coped o bipol. Theefoe, device sizing is necessy o bing he device /f noise cone o n ccepble level <0.5dB noise ipc. i i 00kHz feq
Diec-convesion eceive efeence design 4 dvnges: high inegion ge plfo fo uli- bnd eceive low powe no s good s supehe! Vey popul chiecue fo oden syses such s WiFi, 3G WCDM/UMTS, 4G LTE nd 5G
ge ejec files Low- chiecue: Blocke ige Pssive BPF LN 90 ~ Q 5 Why no void signl ound DC by choosing n fequency h is low enough so files nd cicuiy cn be ineged on chip, ye high enough o void he pobles ound DC. ypicl low fequency is one o wice he signl bndwidh. he single qud chiecue bove sill suffes sensiiviy of ige ejecion o phse nd gin isch. ypicl 35dB ige ejecion is no enough fo os syses o be ble o hndle lge ige signl wih finie dynic nge ineged cicuiy. Need RR clibions he ige ejec files pefo boh chnnel selecion nd ige ejecion he se ie. The design of such files will be discussed in subsequen lecues. Popul chiecue fo syses wih now-bnd signls h hs lge enegy conen close o DC such s Blueooh, GPS, nd GSM
The double qud low- chiecue: 6 Pssive BPF LN 90 90 B D + Σ - + Σ + Q Cn be finie o zeo second C ~ poved ige ejecion due o desensiizion o qudue gin nd phse eo.
7 D C B Q q q q sin cos cos cos cos cos sin sin sin sin sin cos sin sin sin sin sin cos cos cos cos cos sin sin cos cos Signl ph nlysis: Se nlysis s befoe!
Refeences: [].. bidi, Rdio Fequency neged Cicuis fo Poble Counicions, Poc. CCC, Sn Diego, pp 5-58, My 994. [].. bidi, Diec Convesion Rdio Tnsceives fo Digil Counicions, Poc. SSCC, pp 86-87, Feb 995. [3] J. Clos, M. Seye Single-Chip 900MHz CMOS Receive Fon-end wih High Pefonce Low- Topology, EEE JSSC, Vol. 30, no., pp 483-49, Dec. 995. [4] B. Rzvi, Micoeleconics, Penice Hll P. 998. [5] J. Clos, M. Seye, CMOS Wieless Tnsceive Design, Kluwe cdeic Publishes. 997. [6] Pcicl Syse Design, Willi F. Egn, SBN: 0-47-003-9, Hdcove 46 pges, pil 003, Wiley-EEE Pess. 8