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Circuits: Op Amps Page

The Op Amp Page

(**SPECIAL NOTE FOR FINAL PROJECT:  IF you want to use an op amp with Vcc and Ground as we did in the labs, use the LM324.  If you want to use one with +Vcc and -Vcc use them LF353)

Here is 'everything you need to know' about op amps. Why do we love them so much?

1) We can build a huge variety of extremely useful circuits Links to an external site. with them including amplifiers, buffers, inverters, etc.

2) We can use them to isolate input and output circuits. Since the current going in to the op amp =0, the input circuit can be set up so it does not have to 'source' any current (often it can't or shouldn't).  The current for the output circuit comes from the POWER SUPPLY for the op amp, rather than from the input circuit.  The voltage follower/buffer below works on this principle.

Lectures:

Lecture (4-1) Op-Amp Characteristics

Lecture (4-2) Negative Feedback

Lecture (4-3) Ideal Op-Amp Model and Non-Inverting Amplifier

Lecture (4-4) Inverting Amplifier

Lecture (4-5) Summing Amplifier

Lecture (4-6) Difference Amplifier

Lecture (4-7) Voltage Follower

Cookbooks (quick-notes):

Download Op Amp Cookbook.docx

Download Op Amp Cookbook -- Recognizing Inv & NonInv Amps.docx

Download Op Amp Cookbook -- Recognizing Inv & NonInv Amps ANSWERS.docx

Download Op Amps with DC Offsets.pdf

What you need to know about an ideal op amp:

a) with feedback:  Vp=Vn and input currents =0. 

b) without feedback Vo = A(vp-vn) where A is so large that Vo 'rails' between +Vcc and -Vcc (op amp used as switch below, uses that principle)

c) for all cases -Vcc < Vo < Vcc (op amp 'rails out' at (cannot go above or below) power supply voltages)

Quick Video Summaries of common op amp circuits:

Download (Power Point to take notes on)

Op Amp as Switch:

op amp switch Links to an external site.op amp switch

(CC Links to an external site.)

Non-Inverting Amplifier:

op amp noninverting amplifier Links to an external site.op amp noninverting amplifier

(CC Links to an external site.)

Download Op Amp non inv op amp problems.docx

Download Op Amp non inv op amp problems solutions.pdf

Inverting Amplifier:

inverting amplifier Links to an external site.inverting amplifier

(CC Links to an external site.)

Download Op Amp inv op amp problems.docx

Download Op Amp inv op amp problems solutions.pdf

Non-Inverting Summer (adder):

op amp summer (adder) circuit Links to an external site.op amp summer (adder) circuit

(CC Links to an external site.)

Inverting Summer (adder):

op amp inverting summer or adder Links to an external site.op amp inverting summer or adder

(CC Links to an external site.)

Differencing (subtracting) amplifier:

differential amplifier Links to an external site.differential amplifier

(CC Links to an external site.)

Voltage Follower:

op amp voltage follower Links to an external site.op amp voltage follower

(CC Links to an external site.)

Designing Op Amp Circuits:

Here is the original deck of cards I used in class: Download deck of cards print.pptx

You might find this one even easier to use (block diagrams shown via math symbols) Download deck of cards op amps version B.pptx

Rin,Rout for Op Amps (also adding DC offsets to op amp circuits)   Download Rin,Rout and VDC for op amps.pdf

Labs:

Lab 3 - R2R Ladder for Digital to Analog Conversion (DAC) (using the op amp as non-inverting amplifier)  See also  Download OpAmp DtoA conversion.pdf

Lab 4 -- Resistive Sensors  (using the op amp as a switch, and also (extra credit) an inverting amplifier)

Lab 5 -- Op Amp D/A Converter (using the op amp as non-inverting amplifier)  See also OpAmp DtoA conversion.pdf

Intro to Op Amps, How they Work, and how the pins are laid out

Real Analog - Circuits1 Labs: Ch5 Vid1: Operation Amplifiers Links to an external site.Real Analog - Circuits1 Labs: Ch5 Vid1: Operation Amplifiers

(CC Links to an external site.)

Examples:  Review For Midterm Ii

Identifying common op amp circuits:

Download Op Amp Cookbook -- Recognizing Inv & NonInv Amps.docx

Download Op Amp Cookbook -- Recognizing Inv & NonInv Amps ANSWERS.docx

Analysis of op amp circuits:

Download OpAmp (diff amp) Node Voltage Example.pdf