Operational Amplifier Linear Introduction Operational amplifier or opamp

Operational Amplifier Linear

Introduction ØOperational amplifier or op-amp is a circuit of components integrated into one chip (IC Series 741). ØWe will study the op-amp as a singular device introduction

Op-Amp ØOp-amp is a high-gain dc amplifier that has high input impedance and low output impedance. ØA typical op-amp is powered by two dc voltages and has an inverting(-) and a non-inverting input (+) and one output. introduction

Op-Amp Five important pins – – – introduction 2 – The inverting input 3 – The non-inverting input 6 – The output 4 – The negative power supply V- (-Vcc) 7 – The positive power supply V+ (+Vcc)

Op-Amp Symbols ØSymbol shown in a most commonly use; introduction

Basic Op-Amp ØInput terminal (+) is called noninverting input (V+) and input terminal (-) is called inverting input (V-). ØVo will be in phase with the input at V+ , while it will be 180° out of phase with the input at V. ØThe used of +ve and –ve supply voltages allows the output to swing in both +ve and –ve directions. introduction

Basic Op-Amp introduction

Basic Op-Amp ØAn ideal op-amp has infinite gain and bandwidth, we know this is impossible. ØHowever, op-amps do have: Øvery high gain Øvery high input impedance(Zin = ∞) Øvery low output impedance (Zout = 0) Øwide bandwidth. introduction

Op-Amp Transfer Characteristic ØThree regions of operation: linear region, negative saturation region and positive saturation region. introduction

Op-Amp Transfer Characteristic Positive Saturation – where the output voltage exceeds the positive power input Linear Region – where the output voltage is linear based on A (gain) Negative Saturation – where the output voltage would be less than the negative power input

Op-Amp Transfer Characteristic introduction

Op-Amp DC Offset Parameters Input Offset Voltage ØOp-amps tend to produce a small dc voltage called output error voltage (VOUT(error)). ØThe data sheet provides the value of dc differential voltage needed to force the output to exactly zero volts. This is called the input offset voltage (VIO). introduction

Op-Amp DC Offset Parameters Input Offset Voltage introduction

Example Sketch the op-amp transfer characteristic given open loop gain (AOL) = 103 and offset voltage (VOI) = 10 m. V. The op-amp is supplied with ± 10 V. Give the range of the linear and non linear region. Since VOI = 10 m. V so we need to shift 10 mv to the left Solutions: Given AOL = 103 and op-amp is supplied with ± 10 V introduction Linear Region: -20 m. V ≤ Vin ≤ 0 V Non-Linear : Vin > 0 V, Vin < -20 m. V

Op-Amp DC Offset Parameters ØThere are other input parameters to be considered for opamp operation. The input bias current is the dc current required to properly operate the first stage within the opamp. The input impedance is another. Also, the input offset current—which can become a problem if both dc input currents are not the same. ØOutput impedance and slew rate—the response time of the output with a given pulse input—are two other parameters. introduction

Application in Op-Amp • There are 2 types of application in op-amp – Linear application – Non-linear application • Linear application is where the op-amp operate in linear region: – Assumptions in linear application: • Input current, Ii = 0 • Input voltage: V+=V • Feedback at the inverting input application

Application in Op-Amp • Non-linear application is where the op-amp operate in non-linear region • By comparing these two input voltages: positive input voltages, V+ and negative input voltage, V- where: VO = VCC if V+ > VVO = -VCC if V+ < V • Input current, Ii = 0 application

Op-amp Circuit Application – Non-Inverting Amplifier – Summing Amplifier – Unity Follower – Difference Amplifier – Integrators – Differentiators application

Linear Applications application

Linear Applications • Consider non-inverting configuration…

Linear Applications • The Concept of Virtual Circuit Ø Thus, for non-inverting configuration, we can assume that a short circuit exists between the two input terminals. application

Linear Applications • Non-Inverting Amplifier application

Linear Applications • Non-Inverting Amplifier application

Linear Applications • Inverting Amplifier ØThe input signal and feedback signal are both applied to the inverting output application

Linear Applications • Concept of the Virtual/Earth Ground application

Linear Applications • Inverting Amplifier ØThus for inverting configuration, we can assume that the inverting input is virtually connected to ground application

Linear Applications • Inverting Amplifier application

Linear Applications • Inverting Amplifier application

Linear Applications • Unity Follower ØProvides a gain of unity (1) From the circuit; Vo = V Where as we known; V-=V+ Hence; Vo = V + = V 1 application

Linear Applications • Summing Amplifier Ø Also known as weighted summer IRf IR 1 IR 2 Ii = 0 IR 3 application

Linear Applications • Difference Amplifier IR 4 IR 2 Ii = 0 IR 1 Ii = 0 IR 3 application

Linear Applications • Difference Amplifier IR 4 IR 2 Ii = 0 IR 1 Ii = 0 IR 3 application

Linear Applications • Difference Amplifier IR 4 IR 2 Ii = 0 IR 1 Ii = 0 IR 3 application

Exercise 1 Identify OP 1 and OP 2. Find VO 1 and VO OP 1 exercise VO 1 OP 2

Exercise 2 Identify OP 1, OP 2 and OP 3. Find V 2 and V 3 OP 2 OP 1 VO 1 OP 3 exercise

Exercise 3 Identify OP 1, OP 2 and OP 3. Find VO OP 1 OP 3 OP 2 exercise

Exercise 4 Find VO? exercise