BS.T.J BRIEFS HILO. An Improved Transmission Scheme for Semiconductor Switehing Networkt By RR. LANE Foremost among the prablems in semioonolur ewitching network implomeutaions ia the difielty of fabresting 8 remienndustor eros. Thine which duplicates the characteristics of metalic orospeints of easly aezo on” napednaee, A lie reprint impedance is necomary {orl signal lee shrouzh Fue switching eetwoxe 'struasmietion levine it deseited inthis paper which reeves the reciirerent dor low ercteosint “ow” Impedance and which allows ‘rotllatvoiceband trammision characteristics with unbalanced emiooncuetor svivehing: nelnarks, lw technique ealed ILO oon ‘erls voltnge inputs to Ove etwonk into cumrent changes Wing 6 ih Input impedance surtent eouroe end tranamite the etre changes theongh the network eresepints by modulting the network bas Carron. A low outs ipedanso is provided at the networks nereving terminal, wae the modulstel cents arp denned to reeover normal Vvoltge-curent levels ‘The ee equivalent of the HILO cura trsmamiaion cious shown in Fig. 1 Aswning idevlied sranwiar charactosticn (zero mitt inpadance, infin sollte impedance, abd Uni ay inp igo fe, controls she eurrentsomree, Q, converting tae faput into weurrent Change + = ex/R. ‘The cutout change ie transmitted theough a net- Svovk path and i supplied e2 an input to « eommin base amphir, Qe, we ce resiving terminal. The reeovorod eutput is given Ty cy = Ry = RelBe a Atnough equstion {1} ance idalzed teansintr characteriation 4o 1000 ee pu orn THLEENIONL JOURNAL) MAOH 10 Fla 1 Cartman Gre foramen catia nea 91 Ikcep the exposition simple, the equation remains renably vel for ‘oicechand applications sig Darlington traninor palm and normal {Goo-ah) entsminsion impearee eve ine information iy transmitted only a & out change within the siting network, creep rsitaee and ersspoint soninesri- ties do no impa te craters of Te recovered igual. Recovered Imaamision Tove! heoomesprimacily uelion of Haid Ry An are sult, network gain Can) sherateritin ean be aneuately comtoled, Tn addition to providing good signal temamissicn capability, the technique slowe nearly ‘dea! fnstion batwenn network paths, Capaci- tive crosstalk ie minimized because only a small voltage charge i pro- dduced within the network trnamission peth ea e romlt of th ta mitted current changes, Thi is tho rel of «low input impedance at the eommen bere output sage dad the raw of rately Tow eels recitence of the nctwork erorspats Tnvuctive eroatalk. is reduoed boeauso the hich output impedance of the garment source driver makes the tranimitted currents rltively fenative to inductive coupling botween tori pot As an exuraple of wurent teevanisson, Fi. 2 illest he Biwi, tranemietion, ard. conttel eirmitry nenerzary Zor operating. am Valanced thyristor network, Only 4 single dition of seanamniaon is thown. Fors hidireional wonnontion, a sea, ities! ere ie eid "To establish a convection themngh the network, « cowcecr signal ‘a oped the tema enna. Tie ngnal ata th eontre Hipp, thereby cumming of Q,. Asa reult urrent sores trngitor, Q, and a, become forward Biased. The eosnre signal alse matiaten whieh llowe Qe mal to arate daring aleton srsrcunuUcroR TaANSMISION 101 Next, approprinte thyristor bwse selection lines ore pl taivenely ta form a path through the wetwonk stags. Crospoinss are tetveted when the selected eurent path spponr=l the eathode termina (ind when h Uhyvistor selection costae signal i applied at the base terminal. Ths, thyristors (ure on in soquence stsrting with the stage rane the xomeork input terminal llding curt for tho erapoints is supplied through thyristor ‘vege terminals of sucresive stages until a puth has been established from he transiting lo the receiving tenaina. AL this time, aypro« Pate holding surrens & supplied through Q, and Q, and thyristor Feletion inputs may Iie ttminated. Fvaly, the CONNECT ipa is ro- moved, canting Q, to tutu of and frsing Q, seu Qs ts function as cure ‘Supply voltage Vis selected toot the lve of the euront sures ooh twctor voltage (@, std Q.) 8 higher potnntal than the thyristor bese felocton pus, This prevents fanty counceton to already wot nst- work paths. ‘A hetnor: path is ciseounodted by applying miscontncr input to the contol fip-flop. This cnuses Qj to anturete, terminating the ‘euros fla i the welwotle path Uaeby tearing down the eonnee- tion bs Tig 2. "Thosteratmck ning cen asa, 1092 eymum avenexerzomsreut sora, ABO 671 A los-lem eletroni hybrid can be corubined with the tranamiaion ‘and biaring eireits to eonvert twa uniditetionsl tennenission pathe i the avitehing network to bidieetional tranaission paths st the net- ‘work terminal, Figure & showe the ae esvalen ofthe hybrid cet, (Cureentaeppaaring st the asta af Q, ae tnarited to tho amit of Q, via, wheres, currents at che emitter of Q, ate tranamittad to (via Q, and Q,. Invertr stage Q, is necessery fur proper phase zela- tionship i the fexsmiai loop. The eect ean bo described by tho following eyaransters jr-fe ana. fi ® youn 9 by, cont, bey, r= Bey, ° ™ neater © ‘Tho input impodenes at the two input terminala i given by Ys RRR ' 1, 7 Tilt eo amaqeoxovoren mawunssion 101s, __=.. and ) “To cancel the inven let of By, and Bison input impstane teo identical ereuts ure ewended betsoen nctwork terminals. Assuming yr by, Ry, ABA Ry oF tho siesta nro Mouser, the cret ata we tgratar and termination fmpmlu.ces ape Tested through Ube netwoec (othe opus terminal ule Kast Bn Ro, tam Be 0 or eyunmatry, to stage nee vouaeeted as abown in Fig 4 to form switching nabrenk ith uvidcetinaal ator pate and idivecionel tel terminals ‘The contebutions and wuggestions of W. Th. Gaurt, 1, Iweren and 1D, Vluck on the hyd eioaie are gratoflly ashnowadged.