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Tim Green1

In honor of National Puzzle day here in the United States of America, I humbly present six op amp puzzles for you to puzzle on until your puzzler is sore – or at least until next week when I will publish the right answers! 

I’ve even provided you with some key op amp specifications to help in Figure 1.

PARAMETER

 

 

CONDITION

OPA735

UNIT

MIN

TYP

MAX

 

 

Vs=±5V

unless otherwise noted

 

 

 

 

Operating Voltage Range

VS

 

±1.35

 

±6

V

Common-Mode Voltage Range

VCM

 

(V-) -0.1

 

(V+) - 1.5

V

Short Circuit Current

ISC

 

 

±23.5

 

mA

Voltage Output Swing from Rail

VO

IOUT=+5ma (source)

 

4.70

 

V

 

VO

IOUT= +10ma (source)

 

4.44

 

V

 

VO

IOUT= +20ma (source)

 

3.85

 

V

 

VO

IOUT= -5ma (sink)

 

-4.81

 

V

 

VO

IOUT= -10ma (sink)

 

-4.62

 

V

 

VO

IOUT= -20ma (sink)

 

-4.00

 

V

Input Offset Voltage

VOS

 

 

1

5

uV

Input Bias Current

IB

VCM=VS/2

 

±100

±200

pA

Input Offset Current

IB

VCM=VS/2

 

±200

±300

pA

Figure 1: Key Op Amp Specification for OPA735

Without any further ado, let’s get puzzling!

Puzzle #1: What is Vout?

 

Puzzle #2: What is Vout?

Puzzle #3: What is Vout?

Puzzle #4: What is Vout?

Puzzle #5: What is Vout?

Puzzle #6: What is Vout?

Please do not post your answers so that those who are still puzzling can keep on puzzling, until next week when I publish the answers in my next blog post. I’ll be monitoring the comments and will jump in to answer questions and hints, if you get stuck.

A special thanks to my boss, Art Kay, for the starter seed of the idea for these op amp puzzles. 

Happy puzzling!

PS: If you thought this was fun, you might want to check out these posts from long-time TIer and retiree Bruce Trump.

 

 

Anonymous
Parents

  • Ken, if you need network theorems and SPICE to deal with these you must be a bit wet behind the ears. They are all standard common circuits well known since the 60's. The kicker on these is the data sheet, and your network theorems won't help you there! It's non-linear! Hint: most of them are jammed against the rails.

Comment

  • Ken, if you need network theorems and SPICE to deal with these you must be a bit wet behind the ears. They are all standard common circuits well known since the 60's. The kicker on these is the data sheet, and your network theorems won't help you there! It's non-linear! Hint: most of them are jammed against the rails.

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