Submitted By:Md.Al Imran Bhuyan(143-

19-1616)

Md.Nazmul Hasan(143-19-1611)

Sabuj Mandal(143-19-1618)

An operational amplifier in which the input signal is

applied to the ungrounded positive input terminal to

give a gain greater than unity and make the output

voltage change in phase with the input voltage.

To start the design process, we must determine the

following requirements based on the intended

application:

Voltage gain

Frequency range

Load resistance

Maximum input voltage

As an example of the design procedure, let us design a

non inverting amplifier with the following

characteristics:

1. Voltage gain 8

2. Frequency range DC to 5 kilohertz

3. Load resistance 27kilohms

4. Maximum input voltage 800 milli volts RMS

We know there some resistors and a input signal

and an output signal exist in an op amp.

Firstly we have to determine an initial value for R1

resistor.

Generally, neither resistor should be less than 1.0 Kilo

ohms nor more than 680 kilo ohms unless there is a

compelling reason for them to be so.

From this rule, we select R1 as 4.7 kilo ohms.

Now we have to determine the value of RF.

RF can be computed from the voltage gain

equation,

We know that the Gain of an Operational Amplifier

is,

For the present design example, we compute RF as

below :

Now we need to find out the Value of

Compensation Resistor (RB).

We know that,

Now we have to determine the Required Unity

Gain Frequency.

Now we have to determine the Minimum Supply Voltages .

To find out this we have to first find out maximum output voltage

For our example, the maximum output voltage will be

The minimum power supply voltage can be determined

by the equation below:

At last, we have to determine the Required Stew

Rate

Finally we find the operational amplifier like below :

Now we are going to show that how to solve a

mathematical problem of an non inverting operational amplifier.

Here is an non inverting op amp figure below :

From that figure you may be asked to find out some

parameters of the op amp like below:

Voltage gain

Input impedance

Input current requirement

Maximum output voltage swing

Slew-rate limiting frequency

Maximum input voltage swing

Firstly we show here how to find out the Voltage Gain .

We know that for an non inverting op amp,

Voltage Gain,

Now for the circuit we find,

Finally we can express the voltage gain in decibel as

below :

Now we have to find out the Input Impedance.

We know that,

Where Rop is the value of input resistance

provided by the manufacturer and Av is

the open-loop voltage gain of the op amp.

So we find for the circuit,

Here we take gain Av= 200,000 because of the

open loop.

Now we have to determine the Input Current

Requirement.

By applying Ohm’s law we can write from the circuit,

For finding Maximum Output Voltage Swing,

We know that,

Now we find out the Slew-Rate Limiting Frequency .

We know that,

At last we have to find out the maximum input

voltage swing of the operational amplifier.

We know that,

So by this way we can calculate all the

important terms to solve the mathematical

problem of an non inverting operational amplifier.