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