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## “Op-Amp” Operational Amplifier

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**“Op-Amp”Operational Amplifier**• Non Inverting Amplifier • Inverting Amplifier • Adder • (and Subtractor using an Inverter) • Differential Amplifier • Integrator • Differentiator Op-Amp name derives from early usage of these elements in performing mathematical operations in analog computers.**Three Ways to Examine Op-Amp Behavior**• Consider as an Ideal Op-Amp Component • Consider as a Feedback Model and Examine Behavior • Perform Conventional Circuit Analysis**VE = VIN+ - VIN-**VOUT = a * VE VIN- VIN+**Ideal Op-Amp Model**VE = VIN+ - VIN- VOUT = a * VE**Behavior of Feedback Model**of Non Inverting Amplifier**Behavior of Feedback Model**Summary**“Op-Amp”Operational Amplifier**• Non Inverting Amplifier • Inverting Amplifier • Adder • (and Subtractor using an Inverter) • Differential Amplifier • Integrator • Differentiator Op-Amp name derives from early usage of these elements in performing mathematical operations in analog computers.**a (V+ - V-)**Differential Amplifier Circuit Analysis**a (V+ - V-)**Differential Amplifier Circuit Analysis**a (V+ - V-)**Differential Amplifier Circuit Analysis**a (V+ - V-)**Differential Amplifier Circuit Analysis**a (V+ - V-)**Differential Amplifier Circuit Analysis ZF/ ZG**v1**v1 vid / 2 v2 vid / 2 vicm v2 Model of inputs with common-mode and differential-mode components Original Inputs vi1 vi2 Common Mode Rejection Ratio**Common Mode Rejection RatioCMRR**whereAis the differential mode gain andAcmis the common mode gain Ideally:CMRR Typically: 60 dB CMRR 120 dB**Differential Amplifier Circuit Analysis**with Component Imbalance**Differential Amplifier Circuit Analysis**with Component Imbalance**Differential Amplifier Circuit Analysis**with Component Imbalance**Differential Amplifier Circuit Analysis**with Component Imbalance**Differential Amplifier Circuit Analysis**with Component Imbalance**The Maximum Power Transfer Theorem simply states, the**maximum amount of power will be dissipated by a load resistance when that load resistance is equal to the Thevenin/Norton resistance of the network supplying the power.**To create the Thevenin Equivalent Circuit we need:**• Value of the Thevenin Voltage Source • Value of the Thevenin Resistance**-**Ro vo Rd vd ii + io Avd - vi RL + CL Input and Output Impedances of Noninverting Op-amp Configuration The unity gain buffer input impedance is much higher than the op-amp input impedance Rd. The amplifier output impedance is much smaller than the op-amp output impedance Ro.**R2**R2 vref R3 R3 R4 R4 v1 v2 vout R1 Instrumentation Amplifier**Instrumentation Amplifier Example**Burr-Brown INA118 Parameters: Gain:**R2**R2 C R3 R3 R4 R4 R v1 v2 vout 2R1 Instrumentation Amp (cont.) A feedback network may also be included with the instrumentation amplifier. vdiff = v2 - v1