The 741 Op-Amp ** Circuit Description ** * power supplies Vcc 25 0 DC +15V Vee 26 0 DC -15V * differential-mode signal level Vd 101 0 DC 0V Rd 101 0 1 EV+ 1 100 101 0 +0.5 EV- 2 100 101 0 -0.5 * common-mode signal level Vcm 100 0 DC 0V * 1st or input stage Q1 4 1 12 npn Q2 4 2 13 npn Q3 7 3 12 pnp Q4 8 3 13 pnp Q5 7 9 10 npn Q6 8 9 11 npn Q7 25 7 9 npn Q8 4 4 25 pnp Q9 3 4 25 pnp R1 10 26 1k R2 11 26 1k R3 9 26 50k * 2nd stage Q13B 16 6 25 pnp 0.75 Q16 25 8 14 npn Q17 16 14 15 npn R8 15 26 100 R9 14 26 50k Cc 8 16 30p * output or buffer stage Q13A 17 6 25 pnp 0.25 Q14 25 17 23 npn 3 Q18 17 18 19 npn Q19 17 17 18 npn Q20 26 19 21 pnp 3 Q23 26 16 19 pnp R6 22 23 27 R7 21 22 27 R10 18 19 40k * short-circuit protection circuitry Q15 17 23 22 npn Q21 20 21 22 pnp Q22 8 20 26 npn Q24 20 20 26 npn R11 20 26 50k * biasing stage Q10 3 5 24 npn Q11 5 5 26 npn Q12 6 6 25 pnp R4 24 26 5k R5 6 5 39k * transistor model statements .model npn NPN ( Bf=200 Br=2.0 VAf=125V Is=10fA Tf=0.35ns + Rb=200 Rc=200 Re=2 Cje=1.0pF Vje=0.70V Mje=0.33 Cjc=0.3pF + Vjc=0.55V Mjc=0.5 Cjs=3.0pF Vjs=0.52V Mjs=0.5) .model pnp PNP ( Bf=50 Br=4.0 VAf=50V Is=10fA Tf=30ns + Rb=300 Rc=100 Re=10 Cje=0.3pF Vje=0.55V Mje=0.5 Cjc=1.0pF + Vjc=0.55V Mjc=0.5 Cjs=3.0pF Vjs=0.52V Mjs=0.5) ** Analysis Requests ** .OP .DC Vd -400uV -200uV 10uV ** Output Requests ** .PLOT DC V(22) .probe .end