Takehome3 - co(SAT)-I RC then I co(SAT) ≥ 41/6mA+2.4mA...

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EE 312 Digital Electronics Take Home Exam 3 1) a) Diode turn on voltages are 0.7V. QO cut-off, VOH=5V, then Vce(sat)=0.2V. QO turns on when VBE(QO)=0.7 V, and VIL=VBE(QO)+2*0.7+VBE(QL)-0.7=2.1 V QO saturates when VBE(QO)=0.8 V, and VIL=VBE(QO)+2*0.7+VBE(QL)-0.7=2.2 V V OL =V CE,SAT =0.2V for input voltages greater than 2.2 V. b) For output high case, reverse-biased diodes sink very little current, there is no restriction on current flowing, so NH=Inf. For output low case, D1 is OFF, D2, D3 are ON, QO is SAT and QL is F.A. N=I OL / I IL I IL =(5-0.7-0.2)/6K=4.1/6mA I RC =(5-0.2)/2K=2.4mA I OL= I co(SAT)- I RC I E =(V cc -2V D,on -V BE,L(ON) -V BE,O(SAT) )/ ρ*R B= (5-0.7-2*0.7-0.8)/4.2K=0.5mA Voltage drop on (1-ρ)*R B is negligible. I RD=( V BE,0(SAT)- (-0.2))/R D=( 0.8+0.2)/10K=0.1mA
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I B,o =0.5-0.1=0.4mA I co(SAT) =sigma*βf*I BO(SAT) =12 mA I OL = I co(SAT) - I RC = 12 mA – 2.4 mA= 9.6 mA N=14 c) N=10, I IL =(5-0.7-0.2)/6K=4.1/6mA I OL =N*I L ≥41/6 mA I RD =0.1 mA I RC =2.4 mA I E= 2.1/(ρ*R B ) I OL= I
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Unformatted text preview: co(SAT)-I RC then I co(SAT) ≥ 41/6mA+2.4mA then I BO(SAT) ≥ (41/6mA+2.4mA)/(0.8*50) I BO(SAT) ≥ (41/6mA+2.4mA)/40 I BO(SAT) =I E-I RD 41/6mA+2.4mA≤40*( I E-0.1) 41/6mA+2.4mA≤40*(2.1/(ρ * 6K)-0.1) 13.233≤14/ρ For all rho between 0 and 1, this condition is satisfied. d) Pavg=(P OH +P OL )/2 P OH =V CC* I IL =5*(5-0.9)/6K=3.416mW (No current flow from other supplies) I ρRB =(V cc-2V D,on-V BE,L(ON)-V BE,O(SAT) )/rho*R B= (5-0.7-2*0.7-0.8)/4.2K=0.5mA I RC = ( V CC-V CE,SAT )/R C =(5-0.2)/2K=2.4mA I RD =(V BE,SAT-(-0.2))/R D =0.1mA P OL =5 *( I ρRB+ I RC) + (-0.2)(-0.1mA)=14.52mW P avg =8.968 mW 2) V(in) vs V(out) Transient analysis (20p) Rise time: 90ns, Fall time: 2.7 ns Propagation delays: t(plh): 29 ns t(phl):0.15ns (or less than 1ns), tp=tphl*0.5+tplh*0.5= 14.6 ns Rise time: 162 ns, Fall time: 5 ns Propagation delays: t(plh): 60 ns t(phl): 1.8ns, tp=tphl*0.5+tplh*0.5=30.9 ns...
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Takehome3 - co(SAT)-I RC then I co(SAT) ≥ 41/6mA+2.4mA...

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