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Optimization With HSpice

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Before you start optimizing

• What are you optimizing for?

 – Linearity (as in an amplifier)

 – Gain

 – re!uency response

 – "ri#e a$ility

 – %ransition point

 – Spee&

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Before you start optimizing

• Ho' are you going to test the &esigns

!uality?

 – Simulate& loa&ing

• esisti#e

• *apaciti#e

• Both – +n circuit testing

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Optimization synta,

• %he HSpice manual is locate& in

-cg.//0tools0hspice0120123.0&ocs

• %he synta, is &escri$e& in &etail in chapter

45

• %his is a $rief intro&uction

• + 'ill sho' e,amples after'ar&s

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Optimization statements

• 36O"7L mo&elname O8% optimization

 parameters

• 38996 parameter:O8%,,,(optimization rangespecification)

• 3"*; 39*; or 3%9

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Limitations

• >ou can optimize transistor sizes to shift transition points; gain; linearity; etc3

• %ransistor optimization is &ifficult e#en for HSpice36y e,perience has $een that it is mostly useful forai&ing in sizing3

• HSpice is #ery useful for $ias #oltage&etermination3

• +f you are close to the $est choice for anoptimization parameter; HSpice 'ill ha#e &ifficultyfin&ing that $est choice3 +t can get you close;ho'e#er3

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7,ample $uffer 

• @@@@@@@@@@@@@@@@@@@@@@@@

• 36O"7L mo&el4 O8% +%O8%:A

• 38996 %rans8:O8%4 (4C; .; D; 4)

• 38996 %rans

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7,amples gain 5 amplifier 

• @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

• 36O"7L mo&el4 O8% +%O8%:A• 38996 8$#4:O8%4 (A35AA; 3; A3A) 8$#5:O8%4 (31A5; 3; A3A)

• @38996 %$#4:O8%4 (52; A; D; 4) %$#5:O8%4 (51; A; D; 4)

• 38996 %$#4:5D

• 38996 %$#5:..• 38996 %ain:D2

• 3param transpt:transptlo'

• 3"* Eain 3DE 53DE 34 SW778 O8%+6+F7:O8%4 7S=L%S:slopemi&;cur#earea 6O"7L:mo&el4• @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

• 3param slopecur:IJs!rt(5)I

• 3param transptlo':434D• 3param transpthigh:435D

• 3param inter#allo':ItransptJ(transpthighJtransptlo')05I

• 3param inter#alhigh:Itranspt(transpthighJtransptlo')05I

• 3param inter#allo'mi&:I(transptinter#allo')05I• 3param inter#alhighmi&:I(transptinter#alhigh)05I

• 3param inter#alcenter:ItransptJsign((transpthighJtransptlo')05;transptJ(transpthightransptlo')05)I

• 3meas "* slopemi& &eri# #(t4) at:transpt goal:slopecur 'eight:5• 3param i&ealcur#e(#in): Islopecur@(#inJtranspt)transptI

• 3meas "* cur#earea integ par(I#(t4)Ji&ealcur#e(#(ain))I) from:inter#allo' to:inter#alhigh goal:34

• @ a&&itional spice statements are here ($ut not applica$le to this e,ample)• m4 t4 $#4 E&& G