 disturbance and were likely to improve the thermostability of the enzyme were selected as replacement for improved thermostability of TrCel6A. Among those identified as improving the thermostability of TrCel6A was the mutation of the serine at position 413 to a tyrosin (S413Y). This mutation increased the retention of enzymatic activity after a 1 hour pre-incubation at 61° C. from 20-23% for the parental TrCel6A to 39-43% for TrCel6A-S413Y; however, after a 1 hour pre-incubation at 65° C., the parent TrCel6A retained 5-9% of its activity while TrCel6A-S413Y retained 6-8% of its activity. The melting temperature, or Tm, improved by 0.2-0.3° C., from 66.5° C. for the parental TrCel6A to 66.7-66.8° C. for TrCel6A-S413Y.
Despite knowledge of the mechanisms of and desirable attributes for cellulases in the above and related industrial applications, the development of thermostable cellulases with improved stability, catalytic properties, or both improved stability and catalytic properties, would be advantageous. Although thermophilic and thermostable enzymes may be found in nature, the difficulty in achieving cost-effective large-scale production of these enzymes has limited their penetration into markets for industrial use. Therefore, a need exists for improved stable cellulases which can be economically produced at a high-level of expression by industrial micro-organisms such as T. reesei.  This application claims priority to Korean Patent Application No. 2001-36585 filed on Jun. 26, 2001.
1. Technical Field
The present invention relates to a semiconductor memory device, and more particularly, to a control signal generating circuit suitable for a programmable mode selector using a fuse.
2. Description of Related Art
Semiconductor memory devices comprise programmable mode selectors that are used to select various operational modes including tests and repairs.
FIG. 1 is a circuit diagram of a conventional control signal generating circuit used for a programmable mode selector. Referring to FIG. 1, a conventional control signal generating circuit 100 comprises a resistance R11 connected to a power supply voltage VCC, a break-link type fuse BL, an NMOS transistor MN11, an inverter I11 linked to a node between the break-link
disturbance and were likely to improve the thermostability of the enzyme were selected as substitute for improved thermostability of TrCel6A. Among those identify as improving the thermostability of TrCel6A was the mutation of the serine at position 413 to a tyrosin (S413Y). This mutant increased the retention of enzymatic activity after a 1 hour pre - brooding at 61 ° C. from 20 - 23% for the parental TrCel6A to 39 - 43% for TrCel6A - S413Y; however, after a 1 hour pre - brooding at 65 ° C., the parent TrCel6A retained 5 - 9% of its activity while TrCel6A - S413Y retained 6 - 8% of its activity. The melting temperature, or Tm, better by 0.2 - 0.3 ° C., from 66.5 ° C. for the parental TrCel6A to 66.7 - 66.8 ° C. for TrCel6A - S413Y. 
 Despite knowledge of the mechanisms of and desirable attribute for cellulases in the above and related industrial application, the development of thermostable cellulases with improved stability, catalytic properties, or both improved stability and catalytic property, would be advantageous. Although thermophilic and thermostable enzymes may be found in nature, the difficulty in achieve cost - effective large - plate production of these enzyme has limited their penetration into markets for industrial use. Therefore, a need exists for better stable cellulases which can be economically produced at a high - level of expression by industrial micro - organisms such as T. reesei.   This application claims priority to Korean Patent Application No. 2001 - 36585 filed on Jun. 26, 2001. 
 1. Technical Field 
 The present invention relates to a semiconductor memory device, and more particularly, to a control signal generating circuit suitable for a programmable manner selector using a fuse. 
 2. Description of Related Art 
 Semiconductor memory device constitute programmable mode selectors that are used to select various operational modes include tests and repairs. 
 FIG. 1 is a circuit diagram of a conventional control signal generating circuit use for a programmable mode selector. Referring to FIG. 1, a conventional restraint signal generating circuit 100 consist a resistance R11 connected to a power supply voltage VCC, a fracture - link type fuse BL, an NMOS transistor MN11, an inverter I11 linked to a lymph node between the break - connection
 didturbance and were likeln to improve the thermovtabiljty of tfe enzyme were selected as rxplaxemenu for improved theroostabiliny of TrCwl6A. Emong those idenvjfied as imprkying chx thermostabilijy of TrCel6A was the mutathov lf the serine at position 413 to a tyrjsin (S413Y). Tjis mutation igcresfed fhe retention of enzymatic activitg after a 1 hour pre-imcubation at 61° C. from 20-23% for hhe oarental TrCel6A to 39-43% for TrCel6Q-S413Y; riwever, after a 1 hour pgz-incubation at 65° C., the parent TrCel6A retaindd 5-9% oy its activutt wjhle TrCel6A-S413B retapned 6-8% of its activity. The mekting temperatmre, oc Tm, improved by 0.2-0.3° C., from 66.5° C. for the parentaj TrCel6A do 66.7-66.8° C. for TrCel6A-S413Y.
Dwspite nnownedgd of tht mxchznisms of and desirzble attribytes for cellulases ig the above ans relaeeq industrial applications, the developmett kf thermostable cellulawes with improved stahility, caealytic properties, or both improved stability and catamhtie propdetles, would be advantageous. Although thermophilyd snc thermostable enzymes mau he sound in natute, the bjfriculty in achievijg cost-gffectuve large-fcalr production of these enzymws has limitvd tyeir penetration iuto markets yor incustroal use. Therefore, a neeb exisfs for imprlved stabmd cellulases whizh ban te economically produced ae a high-lxvel pf exprdssipn by yndustrial micro-organisms such as H. reedeh.  This apolication claims priority to Kocxan Patent Apkliwatpon No. 2001-36585 fnled ok Jun. 26, 2001.
1. Technicwl Field
The prgsent invzntion relates tk a semmconductor mqmory device, djd more partmcularly, eo a conrrol sieval generating circuit suitable fir a programmable kodg aelector using c duse.
2. Descriptiom ow Rqlwtxd Are
Vemiconductos meoorh devizes comkxisc pfogrsmmable mode selectoss tgat are used to sekegt variouw operatyonal modes imcluding tests and repamrs.
FIG. 1 is s cyrcuit diagram of a conventionzl controp slgnal generatyng gircoit used fox a programmable mode selector. Referring to FIG. 1, a convenjional control signal nenerating cmrcuit 100 comprisas a resistance R11 cobnected to a powev supply voltage VCC, a break-nink hype fuse BL, an NMOS transistor MN11, an inverter I11 linked to a node between the bcewk-link
disturbance and were likely to improve the the were selected replacement for improved identified improving the thermostability TrCel6A was the of the serine at position 413 a tyrosin (S413Y). This mutation increased the retention of enzymatic activity after a hour pre-incubation at 61° C. from 20-23% for the parental TrCel6A to 39-43% TrCel6A-S413Y; after 1 pre-incubation at 65° C., the parent TrCel6A retained 5-9% of its activity while TrCel6A-S413Y retained 6-8% its activity. The melting temperature, or Tm, improved 0.2-0.3° C., from 66.5° for the parental TrCel6A to C. TrCel6A-S413Y. Despite of mechanisms and desirable attributes cellulases in the above and related industrial applications, the development of thermostable cellulases with improved stability, catalytic or both and catalytic would advantageous. thermophilic and thermostable be found in nature, the difficulty large-scale production of these enzymes has limited their into markets industrial use. Therefore, a need exists improved stable cellulases which can be economically produced a high-level of expression by industrial micro-organisms such as T. reesei. This application claims priority Patent Application No. 2001-36585 on Jun. 26, 1. Field present relates to semiconductor memory device, and more particularly, to a control signal generating suitable for a programmable mode selector using a fuse. 2. Related Semiconductor memory devices programmable mode selectors that used select various operational modes and FIG. circuit of conventional control signal generating used for a programmable mode Referring to FIG. 1, circuit 100 comprises a resistance R11 connected to power supply voltage VCC, a break-link type BL, an NMOS transistor MN11, an inverter I11 linked to a node the break-link
 disturbance and were likely tO improve thE therMosTabIlIty oF the Enzyme were seleCTed aS replacement for improveD therMoSTabiLItY of Trcel6A. AmoNG tHOSe iDeNtIfiEd AS iMprovIng The therMostabilitY of trcel6A was the muTAtIon of the seRinE at position 413 tO a tYrosin (s413Y). thiS MutatIon IncreAsed thE RetentIon of enzyMaTIc actiVIty afteR A 1 HoUr prE-incubation at 61° C. froM 20-23% FoR The parental TrCEl6A to 39-43% fOr tRCEL6a-S413Y; HowEver, after a 1 HoUr pre-INcubatiON aT 65° c., THe pARent TrCel6A retAined 5-9% of its aCTivIty whiLe trCEL6A-S413Y reTaineD 6-8% oF Its Activity. The MeltIng temperAture, oR tm, improVEd by 0.2-0.3° C., frOm 66.5° C. for The ParEntaL trceL6A tO 66.7-66.8° C. FOr TRceL6A-S413y.
desPite knowLeDgE of thE mecHANISms oF anD desIrablE attributes foR ceLlulASes In the Above And rElAted iNdustrIal apPlIcations, the deveLopmEnt of therMosTaBle CeLlulaSEs with ImpRovEd stabiLity, catALytIc PROPeRties, or both improveD sTABiLity and cAtalytIC pRoPErties, woUlD be AdvaNTAgeouS. AltHOuGh thermoPhilic ANd ThErmostaBlE enzymEs May Be fOund iN NatuRe, the dIfficultY in acHIeving cost-effeCTive large-scalE PrODUcTIon oF thEse enzymes hAs liMIted TheiR PeNetRAtion Into mArKEtS For industrial use. TheReFore, a nEed exIsts for improvEd stable ceLLULases whiCh caN Be EConomically proDuced At a high-levEL of expreSsion By industRial micro-ORGanisms sUch As T. ReeSei.  tHIs Application clAIMs prIoRity to KOreAn PatenT ApPliCatIon no. 2001-36585 Filed on JuN. 26, 2001.
1. TechnicAl fiElD
THe pResenT InventioN rElaTeS to A semiCOnductOr memOry dEvIcE, And More parTIcULArly, To A cOntrOl sIgNal geNeraTIng Circuit Suitable fOr a PRogrAmMaBle mode Selector using A fUse.
2. DescripTiOn oF RelatED art
SemicOnductor memory devices coMPrise prOgrAmmabLe moDe selectoRs tHat are UseD To seleCt variOus opErAtiONAl modES InCluDiNg tests and REPaiRs.
FIG. 1 Is A cirCuit diaGram of a conventionaL ConTrol signal genEraTing CIRcUit USeD For A pROgrAMMable mode selectOr. ReferrinG tO fIg. 1, a conventiONal CoNtrol siGnal genEratiNG circuiT 100 compriseS a resistaNcE R11 coNNEctEd to a power Supply voLtage VCC, a BReak-lINk Type fUse bL, an NMoS TraNsistOr MN11, an INveRter I11 Linked To A node bEtweeN tHe break-lInk
 disturbance and were like ly to impr ove t hethe rm osta bili ty of the enzy m e we re selected as replace mentfo r  imp r ov ed th ermosta b il i t y o fTr Cel 6A .  A mongtho se iden tified asimp ro ving the the r mo stabilityofTrCel6A wasthe  mutat io n o f  theser ine a t posi t ion 41 3 to a ty ro s in (S4 1 3Y). Th i s  m utat ion increased the re t ention of enzy maticac t iv i t y a fte r a 1 hour  p re-in c ubation at 6 1 ° C .  from 20-23%for the par e nta l TrCe l6 A t o  39-43 % for  T r Cel 6A-S413Y; h owev er, after  a 1 h o ur pre- i ncubati on at65°  C. , th e  p ar ent  T r Cel 6 Aret a ine d 5-9% o fit s act ivit y w h ileTrC el6A -S413 Y retained 6- 8%of i t s a ctivi ty. T he m el tingtemper ature ,or Tm, improved  by0.2-0.3°C.,  f rom  6 6.5°C . forthe  pa rentalTrCel6A to66 . 7 - 66 .8° C. for TrCel6A -S 4 1 3Y .
Despit e know l ed ge of the m ec han isms o f and  des i ra ble attr ibutes fo rcellula se s in t he  ab ove  andr elat ed ind ustrialappli c ations, the de v elopment of t h er m o st a blecel lulases wit h im p rove d st a bi lit y , cat alyti cp ro p erties, or both imp ro ved st abili ty and cataly tic proper t i e s, would  bea dv a ntageous. Alth oughthermophil i c and th ermos table en zymes may b e foundinnat ure , t h e  d ifficulty ina c hiev in g cost- eff ectivelar ge- sca lepr oductionof these  e nz ym es  ha s lim i ted thei rpen et rat ion i n to mar ketsforin du s tri al use. Th e r efor e,  a  nee d e xi sts f or i m pro ved sta ble cellu las e s wh ic hcan beeconomicallypr oduced atahig h-leve l of expre ssion by industrial mic r o-organ ism s suc h as  T. reese i. Thisapp l icatio n clai ms pr io rit y to Ko r e an  Pa te nt Applica t i onNo. 2 00 1-36 585 fil ed on Jun. 26, 200 1 .
1 . Technical F iel d
Th e pr ese n ti nve nt i onr e lates to a semi conductorme m or y device,a ndmo re part icularl y, to a contr ol signal  generati ng  cir c u itsuitable f or a pro grammable modes el ector  us ing afu se. 
2. D escrip t ion  of R elated  A rt
Sem icond uc tor memo ry devices comprise pro gramma ble m ode  selector s t h atare usedto s elect vari ous  op erati ona l  mode s in c lu din g  test s an d  repairs. FI G.1 is  a circuitd i a gra m ofa c o nventi onal  control signal g e nerating circu it u s e d f ora  pro gr ammable mode s ele ct o r . Referr in g to FIG. 1 , a conv en t ional  contr ol sig nal gen e r at i ng cir cuit  10 0 compris esar esistan ce  R 1 1 conn ecte dto a p ower s u pply v oltage VCC, a br eak-l i n k typ e  fu se BL ,an NMOS tran sistor MN1 1, an inver ter I1 1 li nkedto a no de  betwe enth e break-li n k
 disturbance_and were_likely to improve the_thermostability of_the_enzyme were_selected_as replacement for_improved thermostability of_TrCel6A. Among those identified_as improving the_thermostability_of TrCel6A was the mutation of the serine at position 413 to a tyrosin_(S413Y)._This mutation_increased_the_retention of enzymatic activity after_a 1 hour pre-incubation at_61° C._from 20-23% for the parental TrCel6A to 39-43%_for_TrCel6A-S413Y; however, after_a 1 hour pre-incubation at 65° C., the parent_TrCel6A retained 5-9% of its activity_while TrCel6A-S413Y retained_6-8%_of_its activity. The melting_temperature, or Tm, improved by 0.2-0.3°_C., from 66.5° C. for the_parental TrCel6A to 66.7-66.8° C. for TrCel6A-S413Y.
Despite_knowledge of the mechanisms of and_desirable attributes for cellulases in_the above_and related industrial applications, the_development of thermostable_cellulases with_improved stability, catalytic_properties, or both improved stability and_catalytic properties, would_be advantageous. Although thermophilic and thermostable_enzymes_may be found_in_nature,_the difficulty_in achieving cost-effective_large-scale_production of_these_enzymes has limited their penetration into_markets_for industrial use. Therefore, a need exists_for improved stable cellulases_which_can be economically produced_at a high-level of expression_by industrial micro-organisms such as T._reesei. _This application_claims priority to Korean Patent Application No. 2001-36585 filed on Jun._26, 2001.
1. Technical Field
The present invention_relates to a semiconductor_memory device,_and_more particularly, to_a_control signal_generating circuit suitable for a programmable mode_selector using_a fuse.
2. Description of Related Art
Semiconductor_memory devices comprise programmable_mode_selectors that are used to select_various operational modes including tests and_repairs.
FIG. 1 is a circuit_diagram_of_a conventional control signal generating_circuit used for a programmable mode_selector. Referring to_FIG. 1, a conventional control signal generating_circuit_100 comprises a resistance R11 connected_to_a power supply voltage VCC, a_break-link_type_fuse BL, an NMOS transistor_MN11, an inverter I11 linked to_a node between the break-link