Operational Amplifiers

Chapter 14 . Operational Amplifiers

Operational Amplifiers

• Integrated circuit, also known as op amp .• Wide range of applications . Ideal operational amplifier :

- inverting and non-inverting input terminals .

- common mode signal & differential mode signal

- infinite input impedances

- zero output impedance

- very large open –loop gain .

14.2 Inverting amplifiers

Example 14.1 : Analysis of an inverting amplifier

Exercise 14-17

Exercise 14-18

Differentiator Circuit

Active Filters

• Produce bandpass and bandreject filters without using inductors .

• Inductors are usually large, heavy , costly and generate electromagnetic field .

• Fewer components• Transfer function is insentitive to component tolerances .• Allow a wide range of transfer functions .• Inappropriate for monolithic fabrication .

Fig. 12.1.2 Filter Types . Fig. 12.2 Ideal transmission characteristics of the four major filter types : (a)

low pass (LP), (b) high pass (HP), (c ) bandpass (BP) and (d) bandstop (BS) .

Low –pass filter

Bode PlotsExample 1

Bode PlotsExample 2