Key Facts for Lab 24

Chapter 20: Ideal Op-Amps

An operational amplifier (Op-Amp) is a high quality differential amplifier with the transfer function

Vout = G (Vin+ - Vin-)

We call the input Vin- the inverting input and the Vin+ the non-inverting input.

It is usually operated with negative feedback, which trades a loss of gain for a set of amplifier properties that depend only on passive components such as resistors and capacitors. When operating with negative feedback the amplifier obeys the
Golden Rules

1) The inputs draw no current.

2) The output adjusts itself to keep the voltage at the inverting input the same as the voltage at the non-inverting input.

The two most common op-amp circuits are the non-inverting amplifier and the inverting amplifier.

The non-inverting form has the transfer function and a nearly infinite input resistance. NOTE formula in book is WRONG!

The inverting amplifier has the transfer function and the input resistance R1.