WEEK 15: FINAL CORRECTING DEVICES: AMPLIFIERS

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Sections: Basic | Circuits | Op-Amps

Basic Amplifiers

Definition. Amplifiers are three-terminal devices used in control systems. There are two inputs: positive or the non-inverting terminal and the negative or the inverting terminal. The third is call the output terminal.

Fundamental Equation:

e_OUT = - A (e₁ - e₂)

Where:
e_OUT = Output voltage
A = Open loop voltage gain, common value, 10⁵
e₁ = Voltage-to-reference at terminal no. 1
e₂ = Voltage-to-reference at terminal no. 2

Staturation voltages is usually ± 10 volts.

Assumptions. To perform matematical operations, assume that the amplifier has:
1. Infinite Input Impedance. No current flows in the amplifier input.
2. Zero Output Impedance. Changes in load impedance does not affect amplifier's voltage output.
3. Infinite Common Node Rejection. Amplifier responds only to the voltage applied between its input terminals

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Sections: Basic | Circuits | Op-Amps

Amplifier Circuits

Circuitry. Here under are the basic circuits involving amplifiers
1. Voltage Follower
2. Gain Amplifier
3. Operational Amplifiers
a. Differential Op-Amps
b. Voltage-To-Current Op-Amps
c. Integrator Op-Amps
d. Differentiator Op-Amps
e. Comparator Op-Amps

Voltage Follower. Used as a buffer stage.

Voltage at negative input is dictated by the output voltage. If the output voltage differes from the circuit input voltage by a small error, then the amplifier input difference voltage will be set-up of such polarity that will reduce the output voltage error.

Gain Amplifier.

Operational Amplifiers

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