• An operational amplifier also has zero output impedance, ( Z = 0 ).
• Op-amps sense the difference between the voltage signals applied to their two input
terminals and then multiply it by some pre-determined Gain, ( A ).
• This Gain, ( A ) is often referred to as the amplifiers “Open-loop Gain”.
• Closing the open loop by connecting a resistive or reactive component between the
output and one input terminal of the op-amp greatly reduces and controls this open-loop
gain.
• Op-amps can be connected into two basic configurations, Inverting and Non-inverting.
The Two Basic Operational Amplifier Circuits
For negative feedback, were the fed-back voltage is in “anti-phase” to the input
the overall gain of the amplifier is reduced.
For positive feedback, were the fed-back voltage is in “Phase” with the input the
overall gain of the amplifier is increased.
By connecting the output directly back to the negative input terminal, 100%
feedback is achieved resulting in a Voltage Follower (buffer) circuit with a
constant gain of 1 (Unity).
Changing the fixed feedback resistor ( Rƒ ) for a Potentiometer, the circuit will
have Adjustable Gain.
Op amp Pin configuration
The pin configuration of op amp is as follows
