Electronics The sixteenth and seventeenth Lectures

Thirteenth weekهـ 1437/ 2/ 6 -3

السلمي / سمر أ

Outline for today Chapter five and six: Linear & Digital Electronics

Operational Amplifiers

Operational Amplifiers, its symbol, its parts

technical terms used in operational amplifiers

Operational Amplifiers’ types:

Non Inverting Amplifier, Inverting Amplifier , Unity Amplifier , Summer

Amplifier , Differential Amplifier , Voltage Comparator, Integrator

Amplifier and Differentiator Amplifier

Ideal & Real Amplifiers

Solving the fourth homework

Time of Periodic Exams The Second periodic exam in / 2 / 1437 - 1110هـ , Please everyone attend in

her group

The Forth homework

I put the third homework in my website in the university homework Due Tuesday

5 / 2/ 1437 H H in my mailbox in Faculty of Physics Department , I will not

accept any homework after that , but if you could not come to university you

should sent it to me by email in the same day

The Fifth homework

I will put the forth homework in my website in the university homework Due

Tuesday 19 / 2/ 1437 H in my mailbox in Faculty of Physics Department , I will

not accept any homework after that , but if you could not come to university you

should sent it to me by email in the same day

Linear & Digital Electronics introduction: Electronic Engineering is divided into two major types:Electronics Analogue (or Linear): type of electronic engineering specializes in electronic circuits that are placed in using amounts and values of electrical tension and intensity of electric current in the area extends between two values minimum value and a maximum value where it can take the stress and electric current any value between them. Then mathematically, there are infinity of possible values for each field analog

Digital Electronics : type of electronic engineering specializes in electronic circuits that are placed in using amounts and values of electrical tension and intensity of electric current in the area extends between two values minimum value and a maximum value where it can take the stress and electric current any value already of prepared values . Then mathematically there are a limited number of values in each field of digital.

In many electronic devices use the two systems by converting from analog sine wave or a digital or square wave or vice versa

Linear & Digital Electronicsintroduction :

the most important famous of these circuits is integrated circuit (IC) which is

divided into two parts:

Analog integrated circuits: (dealing with sine signals because it depends on the

work of operational amplifiers)

Digital integrated circuits:(dealing with digital signals or square waves because it

depends on digital logic or binary system)

Operational Amplifiers:Operational Amplifiers : a linear amplifier with Direct Coupled, abbreviation

(Op –Amp). It has high value gain, distinguish usually small size, not affected by

changing temperature and used in amplification (they have a great ability to

magnification entrances signals of alternating and direct ). In addition to filtration,

opening and closing circuits (switch) and do calculations operations (addition,

subtraction, integration and differentiation). Finally used in building Analogue

Computer.

Operational Amplifiers’ symbol:

Operational Amplifiers’ parts :

1- two parties to power supply, one of them connected to a positive voltage and

the other connected to a negative voltage, higher value for them are ± 15 V which

are saturation values ± Vsat (often do not draw a circuit such as in the previous

slide symbol)

2- two entrances: one of them called Inverting Input has negative single (V-) , the

other called Non Inverting Input has positive single (V +)

3- one outlet (Vout)

Internal form External form

Operational Amplifiers’ types:

1) Non Inverting Amplifier

2) Inverting Amplifier

3) Unity Amplifier

4) Summer Amplifier

5) The Differential Amplifier

6) Voltage Comparator

7) Integrator Amplifier

8) The Differentiator Amplifier

Before talking about these types, we should know some of technical terms used in

operational amplifiers

Technical terms used in operational amplifiers 1- Negative feedback :

process connects outside voltage Vout with inside voltage Vin(here the negative

entrance inverter) in a way able to delete the part of inside voltage.

It has many benefits such as reducing noise in input signal and thus output.

amplifier divided to two types in term of existence inverter feedback:

1- Open Loop Amplifier : there is no inverter negative feedback

2- Close Loop Amplifier : there is inverter negative feedback

The figure (the right for Open Loop, the left for Close Loop) In some cases, such as amplifier of comparative voltage has a positive feedback (reached with positive input non inverter)

Technical terms used in operational amplifiers

2 - Differential Input Voltage ) VID (: is the maximum voltage difference

between inverter and non inverter entrances ( VID = V- - V+ )

3 - Input Resistance (RI (: is the resistance in one of two entrances or both.

4- Output Resistance) RF (: is the resistance in output which called in same

time

feedback resistance

5- Input Bias Current) IIB (:is the average currents of two entrances when

output is zero voltage

6- Input Offset Voltage (Vos) : is the voltage which should be applied between

two entrances to get zero output voltage

7- Input Offset Current) Ios : (is the difference between currents entrances when

output is zero voltage

Technical terms used in operational amplifiers

8- Voltage Gain) Av(: is the ratio between output voltage and input voltage

There are two types of voltage gain, one open circuit Aol and the other closed

circuit Acl and the relationship between them where β feedback coefficient

9 -Slew Rate) SR : (is equal to the ratio between the change of output voltage to

change time when load resistance is 2 KΩ

10 - Band Width) BW :( is frequencies limit which works at constantly state

11 - GBW: is the product of multiply Band Width with gain

Technical terms used in operational amplifiers

12- Common – mode rejection ratio (CMRR (:

Typically in case of voltages equal to each other V- = V+ , the output voltage

Vout = 0 , but because of the existence a signal at both ends of entrances called

signal common mode which is usually a sign unwanted noise. Thus, amplifier

ability to put out signals common mode measures by ratio called the common

mode rejection ratio

where the first gain is the gain of difference model

and another gain is common mode

Inverting Amplifier

Figure shows inverter operational amplifier, notice that input voltage connected to

the inverter negative terminal, and non inverter positive terminal connected to

grounded, thus, V- = Vin and V+ = 0 . Also notice that the existence of negative

feedback and its resistance in addition to input resistance connected between the

inverter terminal and signal input.

voltage gain coefficient

notice that the feedback current (or outside

current ) is the same input current

Negative here because it inverter and a difference in phase

Inverting Amplifier

For form output wave will be amplifier and reverse entrance wave by180 degrees

as shown in figure

10 kΩ1 kΩ

+ 1v

vi

- 1v

+10v

v0ut

- 10v

Non Inverting Amplifier

Figure shows non inverter operational amplifier, notice that input voltage

connected to the non inverter positive terminal, and inverter negative terminal

connected to grounded, thus, V+ = Vin and V- = 0 . Also notice that the existence of

negative feedback and its resistance in addition to input resistance connected

between the inverter terminal and grounded.

voltage gain coefficient

Non Inverting Amplifier

For form output wave will be amplifier and at the same entrance wave phase

degrees as shown in Figure

20 kΩ10 kΩ

+ 1v

vi

- 1v

+3v

v0ut

- 3v

Unity Amplifier

The output voltage for this amplifier is almost equal to input voltage in value

Vout ≈ Vin . It has the same polarity, therefore it called unit amplifier which is

commonly used in insulation. The figure shows non inverter unit amplifier and we

note the absence of feed resistance in negative feedback. It is also called Follower

Amplifier

voltage gain coefficient

Summer Amplifier

In Figure, we notice inverter amplifier but instead of entering one signal, several

signals enter. Each signal enters has input voltage, resistance and current. They

gather at one point before entering amplifier . This type called Summer Amplifier

because it sum the input signals. the output voltage of summer amplifier is

In the case of similar resistances

output voltage is equal to the sum input

voltages

observed negative because it summer

inverter amplifier

The Differential Amplifier

At previous types of amplifiers, we have noticed the existence voltage input from

one side while the other side connected with grounded. But when the input

voltage or signal connected to inverter and non inverter as in figure, we deal with

difference between input voltages, therefore it called Differential Operational

Amplifier . It grows up the difference between the two input signals.

The output voltage of differential amplifier

Often in this amplifier

RF

RD

Integrator Amplifier Figure shows that inverter amplifier with a negative feedback replaces the output resistance or feedback resistance by capacitor and of course the existence of input resistance. Here, the output signal integrates input signal for time.Output voltage is equal to

Figure shows form of input and output wave in two cases when input waves are square and sinusoidal. The output wave is triangle wave for squared wave and the other sine wave removed by 90 degrees to the left.

The Differentiator Amplifier The differentiator amplifier similar to integrator amplifier by replacing the input resistance by capacitor and the existence of output resistance or feedback resistance Output voltage is equal to

Figure shows form of input and output wave in two cases when input waves are square and sinusoidal. The output wave is positive and negative pulses wave for squared wave and the other sine wave removed by 90 degrees to the right.

Voltage Comparator Amplifier Amplifier used as comparative to voltage in which voltage compares to one of entrances with the main voltage that exists at the other entrance. There are two types of comparisons: inverter voltage comparator (when voltage signal enter on inverter entrance ) and non inverter voltage comparator (when voltage signal enter on non inverter entrance )

It should mention that the comparative exposedoscillate output in existence of small voltages bynoise in entrances. To avoid that, we added resistance feedback positive (connected to positive terminal non inverter)

Voltage Comparator Amplifier

Figure shows waveform of input is sinusoidal and of output is square for non

inverter voltage comparator amplifier which it compares sine wave (having

voltage 5V) with basic continual (voltage being equal to 3V) . Therefore, output

square wave carrying two values saturation. the positive + Vsat (about 15 V) when

it is greater than the basic voltage 3V and negative - Vsat (about -15 V) when it is

smaller than the basic voltage 3V

Ideal & Real AmplifiersThe previous types of amplifiers operation but there are some conditions that make it an ideal amplifier .voltage gain of open circuit infinite :(value of real amplifier at over 20,000 to 200,000).input resistance infinite : the resistance is dividing input voltage and input current when ideal amplifier is Iin = 0 but (value of input current is a small in real amplifier at extent of pA ~ mA).output resistance zero : we notice it in unit amplifier as absence of resistance (but value of output resistance in real amplifier is a small at extent of 100Ω -20KΩ)

band width infinite : in ideal amplifier, frequencies infinite therefore band

width infinite. This applied in unit amplifier .

input offset voltage zero: ideal amplifier zero when input voltage difference is

zero or connected with grounded (in real amplifier input offset voltage has value)

Slew Rate infinite

Common mode rejection ratio zero &noise zero

Solving the fourth homework