741 Op-Amp Circuit . Section 8.1 ( Razavi ) Chapter 12 ( Sedra Smith). History. The first uA741 Op-Amp was designed by Bob Widlar in 1963 at Fairchild Semidconductor . uA702 sold for 300 a piece. uA709 was sold for 70 a piece.
Section 8.1 (Razavi)
Chapter 12 (Sedra Smith)
Solve through trial and error
(β is high )
(Input Bias Current)
(Input Offset Current)
R into the emitter of Q3: 1/gm3
R into the base of Q1: rπ1+β1/gm3
Differential resistance 2(rπ1+β1/gm3)
Large input resistance since IC is kept small!
Typical input impedance is in excess of 2 MOhms
(Output resistance is small)
Negligible input current
Large input AC resistance
Small AC output resistanceLarge Voltage Gain
Op-Amp is a circuit that amplifies the difference
between the inputs.
As Ao approaches infinity, Vin1-Vin2 approaches 0.
(If A0 is 1000, Vout/Vin=0.999)