RFIC_Lecture_Note_No3_p27-p43 (Active and passive devices)

RFIC_Lecture_Note_No3_p27-p43 (Active and passive devices)...

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ECE695F RFIC Prof. S. Mohammadi MOS Devices and Technology Oxide Tungsten n+ n+ p-well trench p+ p+ n-well poly Oxide TiSi 2 (titanium silicide) to reduce poly gate resistance p - epi p + Dual-well epi process MOS (Metal-Oxide-Semiconductor) unipolar transistors Æ only one carrier exists carrier hole Æ PMOS : slower transistors as holes have lower mobility compared to electrons electron Æ NMOS Technology that uses both NMOS and PMOS is called CMOS (Complementary MOS) - 27 -
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ECE695F RFIC Prof. S. Mohammadi n+ n+ D S G P B at F G V φ 2 ~ channel forms and there will be conduction of electrons from source to drain ) ln( i A F n N q kT = fermi level n+ n+ DS B G V n strong inversion results in conduction at strong inversion there is a fixed charge in the channel F A B qN Q ε 2 2 = potential for strong inversion by increasing gate voltage this charge + channel thickness do not change if the body is not grounded SB F F V + 2 2 source-body voltage - 28 -
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ECE695F RFIC Prof. S. Mohammadi GS V needed to reach strong inversion is called Threshold GS T V V = @ strong inversion ) 2 2 ( F SB F TO T V V V φ γ + + = relates to process and can be adjusted by shallow ion implantation body-effect coefficient Threshold adjustment Æ Threshold voltage varies with substrate voltage (body effect) P S D n+ n+ DS V G V inversion layer deptetion layer - 29 -
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ECE695F RFIC Prof. S. Mohammadi Small V DS S D n+ n+ DS V GS V Resistive operation W X L x V T GS V V you form inversion layer Induced charge ) ( ) ( T x GS OX i V V V C x Q = W x Q v I i n D ) ( = current that goes to drain(D) electron velocity mobile charge dx dV v n n µ = width of channel dv V V V W C dx I T GS OX n D ) ( = DS V L 0 0 = 2 ) ( 2 DS DS T GS OX n D V V V V C L W I : ' OX n n C K = Transconductance factor - 30 -
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ECE695F RFIC Prof. S. Mohammadi when you increase V DS n+ n+ DS V GS V point of strong inversion T DS GS V V V = current saturates ( becomes independent of ) D I DS V T GS DS V V V =
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RFIC_Lecture_Note_No3_p27-p43 (Active and passive devices)...

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