Electronic Circuits-1

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1 Electronic Circuits-1 Prof.Dr.Eng.Ahmad Rateb Al-Najjar SPU 1

2 CONTENT 1. BJT Amplifier 2. FET Amplifier 3. Frequency Response of Amplifier 4. Operational Amplifiers 5. Audio Power Amplifier 6. Linear-Digital ICs 7. Power Supplies 8. IC Technology (optional) SPU 2

3 Chapter 4: Operational Amplifiers 4.1 Introduction 4.2 Basic Differential Amp Circuit 4.3 BiFET & BiMOS differential amplifier circuit 4.4 Basic Op-Amp circuits 4.5 OP-Amp Specifications 4.6 Op-Amp Applications 4.7 Active Filters SPU 3

4 Operational Amplifiers An operational amplifier, which is often called an op-amp, is a DC-coupled highgain electronic voltage amplifier with differential inputs and, usually, a single Output. Typically the output of the op- Amp is controlled either by negative feedback, which largely determines the magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative gain and oscillation.

5 Operational Amplifiers.High input impedance, at the input terminals (ideally infinite) ; and low output impedance (ideally zero) are important typical characteristics.op-amps are among the most widely used electronic devices today, being used in a vast array of consumer, industrial, and scientific devices.

6 Operational Amplifiers Many standard IC op-amps cost only a few cents in moderate production volume; however some integrated or hybrid operational amplifiers with special performance specifications may cost over $100 US in small quantities. Modern designs are electronically more rugged than earlier implementations and some can sustain direct short circuits on their outputs without damage.

7 Operational Amplifiers Features of The Ideal Op.Amp : (Golden Rules: logically deduce the operation of any op.amp circuit) 1-Infinite Voltage Gain,AvD = 2-Input Impedance is,zin= 3-Output Impedance is 0, Zo= 0 4-Infinite BW = & GBWP = 5-Zero input offset voltage(i.e.., exactly zero out if zero in) An Op.Amp contains several DA stages to achieve a VHVG.Applications: Oscillators/Filters/Instrumentation CCT,.etc.

8 4.1 Introduction Ideal OP. AMP SPU 4

10 Differential Mode & Common Mode SPU 5 V o =A cm V i

11 4.2 Basic Differential Amp Circuit SPU 6

12 - DC and AC Operation of Diff. Amp Advantages of Differential Mode SPU 7

13 AC equivalent circuit of differential amplifier V o1 =f(v i1 -V i2 ) V o2 =f(v i1 -V i2 ) SPU 8

14 AC Analysis of Differential Amplifier R E C m i i o i i o d C m i i o o d R g V V V V V V A R g V V V V A 2 / C m i i o o d R g V V V V A R E C m i i o i i o d R g V V V V V V A 2 / Differential Output Single Output

15 AC Analysis of Differential Amplifier Z id = 2βr e : (between B 1 and B 2 ) C m i i o o d R g V V V V A R E C m i i o i i o d R g V V V V V V A 2 / Z id

18 Common-mode connection. SPU 9

19 AC circuit in common-mode connection A cm V V o i r i RC 2 R E EX: R C, R E, β SPU 10

20 Diff Amp with constant-current source I=const R o =

21 Diff Amp with constant-current source SPU 12

22 CMOS inverter circuit

23 CMOS Transfer Characteristics

28 4.3 BiFET & BiMOS differential amplifier circuit High Z i Higher Z i SPU 16

29 CMOS differential amplifier Low Power SPU 17

30 AC equivalent of op-amp circuit Real Op-Amp Ideal Op-Amp SPU 18

31 4.4 Basic Op-Amp circuits Closed-Loop Op -amp Negative Feedback SPU 19

34 Virtual ground in an op-amp. SPU 20

35 Non-Inverting Amp & Inverting Amp SPU 21

36 Adder Circuit SPU 22

37 Integrator Circuit SPU 23

39 4.5 OP-Amp Specifications effect of input offset voltage V IO. SPU 24

40 input bias currents SPU 25

41 Gain versus frequency plot SPU 26

42 Slew Rate SR= V o / t [V/μS]=A CL ( V i / t) A Parameter to Specify the Maximum Rate of Change of the Output Signal Ex: Vo=K Sinωt ; Differentiating,yields :- Δvo /Δt=Kω Cos ωt,then SR=Kω,if ωt=0,then: f max SR 2 K [Hz]

43 Slew Rate Maximum Signal frequency at which an op.amp may operate depends on both the bandwidth (BW) and slew rate(sr) parameters of op.amp. f SR/2πk Or ω SR/k

44 SPU 27

45 SPU 28

47 4.6 Op-Amp Applications Buffer + Inverter Amp SPU 29

48 Applications Of Op-Amp SPU 30

49 Circuit for subtracting two signals

50 Circuit for subtracting two signals

51 Practical V/C Controlled Sources VCVS VCCS CCVS CCCS

52 Practical Voltage-Controlled Voltage Source

53 Practical Voltage Controlled Current Source

54 Practical Current Controlled Voltage Source

55 Practical Current - Controlled Current Source

57 AC millivoltmeter using op-amp.

58 Display driver circuits: (a) lamp driver; (b) LED driver

59 Instrumentation amplifier Z i V o =(1+2R/R P )(V 1 -V 2 )=k(v 1 -V 2 ) Z i

60 4.7 Active Filters Ideal Filter s Response SPU 15

61 Filters Types 1. Passive Filters: (R,L,C) 2. Active Filters: (RC,Op-Amp) 3. Digital Filters: (DSP,A/D & D/A) All of them to have: LPF, HPF, BPF, BRF

62 First-order low-pass active filter

63 Second-order low-pass active filter

64 Different Orders Of Active Filters HPF 1 st Order 2 nd Order Response Plot

65 Band-pass active filter

66 Filter =? R 1 R F R 1 R F V i R V o C 1 C 2 R

67 Band-pass active filter

68 R C R K Vi C Vo

69 R Vi C C R K Vo

70 Vcc= 12V I 3 I 1 R R 1 R C V O C G D T 1 R 2 C B 2 T 2 I r D Z Ri 2 e R T 3 D B 1 R 3 R E C E Ri 1 R O3

Operational Amplifiers. Boylestad Chapter 10

Operational Amplifiers. Boylestad Chapter 10 Operational Amplifiers Boylestad Chapter 10 DC-Offset Parameters Even when the input voltage is zero, an op-amp can have an output offset. The following can cause this offset: Input offset voltage Input