Rarely Asked Questions
Issue 186, February 2021
Adding a Flexible Current Limit
Question: Could I easily and precisely limit a current to my load?VIEW THE ANSWER
Issue 185, January 2021
The Perilous Path from the Transducer to the ADC: What’s an Engineer to Do?
Question: Is there a building block that allows me to take a tiny transducer output signal directly to an ADC input voltage?VIEW THE ANSWER
Issue 184, December 2020
How a 16-Bit Output Module with Voltage and Current Outputs Can Be Controlled with Full Isolation from the Microcontroller
Question: How could I design a microcontroller-controlled isolated 16-bit output module?VIEW THE ANSWER
Voltage Conversion in Four Quadrants
Issue 183, November 2020
Keeping EMI from LED Drivers Under Control
Issue 182, October 2020
Generating Very Low Voltages with Standard Regulators
Issue 181, September 2020
Design of an Adjustable Voltage Output Using a Push-Button Digital Potentiometer
Issue 180, August 2020
Energy Storage Using Supercapacitors: How Big Is Big Enough?
Issue 179, July 2020
Wide Voltage Range Automotive Circuit Protector
Issue 178, June 2020
RMS Power vs. Average Power
Issue 177, May 2020
Ultralow Noise, 48 V, Phantom Microphone Power Supply Using a Tiny DC-to-DC Boost Converter
Issue 176, April 2020
LTspice Audio WAV Files: Using Stereo and Encrypting Voice Messages
Issue 175, March 2020
Current Noise in FET Input Amps
Issue 174, February 2020
On Building Physically Accurate Analog Switch Macromodels
Issue 173, January 2020
Manipulating MCU SPI Interface to Access a Nonstandard SPI ADC
Issue 172, December 2019
“If It Isn’t Broken, Don’t Fix It.” Adjusting the Gain of a Fixed-Gain Difference Amplifier
Issue 171, November 2019
Inductor Current Measurement in Switched Power Supplies
Issue 170, October 2019
A Simple Way to Measure Temperature Using One GPIO Digital Interface
Issue 169, September 2019
Bootstrapping a Low Voltage Op Amp to Operate with High Voltage Signals and Supplies
Issue 168, August 2019
When Smaller Is Better
Issue 167, July 2019
How to Convert Light Intensity Into an Electrical Quantity
Issue 166, June 2019
Discrete Difference Amplifier vs. an Integrated Solution
Issue 165, May 2019
Guidelines for Placing the Inductor on a Switch Mode Power Supply Printed Circuit Board
Issue 164, April 2019
SAR Converter with PGA Achieves Dynamic Range of 125 dB
Issue 163, March 2019
Enablement of Batteryless Applications with Wireless Power
Issue 162, February 2019
A New Spin on a Classic Architecture: Achieving a Fully Differential Output Using Single-Ended Instrumentation Amplifiers
Issue 161, January 2019
Simple Circuit Measures Relative Intensity of Two Light Sources
Issue 160, December 2018
When Grounds Are Separated
Issue 159, November 2018
Driving a Unipolar Gate Driver in a Bipolar Way
Issue 158, October 2018
Overvoltage Protection for RTD-Based Measurement Systems
Issue 157, September 2018
Optimized Power Supply Measurement Setup
Issue 156, August 2018
Home on the Range: Getting Multiple Gain Ranges With Instrumentation Amplifiers
Issue 155, July 2018
Pocket-Size White Noise Generator for Quickly Testing Circuit Signal Response
Issue 154, June 2018
High Speed ADC Power Supply Domains
Issue 153, May 2018
Problem Solver: Multiplying Digital-to-Analog Converter
Issue 152, April 2018
High-Side Current Sensing
Issue 151, March 2018
Dynamic Use of the Disable Pin on an Amplifier
Issue 150, February 2018
Intermediate Voltage to Increase Power Conversion Efficiency
Issue 149, January 2018
Unique Gate Drive Applications Enable Rapidly Switching On/Off for Your High Power Amplifier
Issue 148, December 2017
Synchronous Rectification on the Secondary Side
Issue 147, November 2017
Why Is My Processor Leaking Power? That Sounds Like an Open-Ended Question
Issue 146, October 2017
A Low Power, Low Cost, Differential Input to a Single-Ended Output Amplifier
Issue 145, September 2017
Accelerometer Tilt Measure Over Temperature and in the Presence of Vibration
Issue 144, August 2017
Burned by Low Power? When Lower Current Consumption Can Get You Into Trouble
Issue 143, July 2017
Issue 142, June 2017
Sometimes, a Signal Needs to Ride the Rails
Issue 141, May 2017
Presto! Multiply Your ADC’s Virtual Channel Count with DDC Magic
Issue 140, April 2017
The Case of the Misguided Gyro
Issue 139, March 2017
This Noise Will Keep You Up at Night
Issue 138, February 2017
Issue 137, January 2017
Precision Current Outputs Are Easy to Make
Issue 136, December 2016
Amplifier RF: Think Before you Choose!
Issue 135, November 2016
Because Mr. Ohm Said So …
Issue 134, October 2016
Common Sense for Current Sensing
Issue 133, September 2016
Choosing a Precision Op Amp? Trust Goldilocks.
Issue 132, August 2016
Going Full Tilt
Issue 131, July 2016
Who Killed the Component?
Issue 130, June 2016
Who Ate My dBs?
Issue 129, May 2016
Citius, Altius, Fortius
Issue 128, April 2016
Kalman or FIR Filter for My IMU?
Issue 127, March 2016
When Second Sources Aren't
Issue 126, February 2016
O CMRR, CMRR! Wherefore Art Thou CMRR?
Issue 125, January 2016
Missing Half the Signal
Issue 124, December 2015
Issue 123, November 2015
The Truth About Voltage Feedback Resistors
Issue 122, October 2015
Issue 121, September 2015
Voltage References Can Bite You, Too
Issue 120, August 2015
The Ingenious Gentleman and the Mysterious Paddle
Issue 119, July 2015
Mystery Spur Explained: Don't Blame the DDC!
Issue 118, June 2015
Issue 117, May 2015
Muntzing can save cost, components, and even your sanity
Issue 116, April 2015
Isn’t that gain specification a bit lopsided?
Issue 115, March 2015
Choosing Voltage References
Issue 114, February 2015
Don’t Get Caught Speeding
Issue 113, January 2015
Exposed Paddles and Downbonds Improve Performance and Reduce Pin Count
Issue 112, December 2014
Choosing Analog ICs
Issue 111, November 2014
I Grew Up in the 80s and Survived!
Issue 110, October 2014
ADCs for High Dynamic Range – Successive-Approximation or Sigma-Delta?
Issue 109, September 2014
LEDs are Photodiodes Too
Issue 108, August 2014
The Diamond Plot
Issue 107, July 2014
Overranged Converter Recovers Quickly
Issue 106, June 2014
Discretion is the better part…
Issue 105, May 2014
Looking for Trouble in All the Wrong Places
Issue 104, April 2014
Programmable ADC Input Range Provides System Benefits
Issue 103, March 2014
Issue 102, February 2014
Bits Per Second Make My Head Hertz
Issue 101, January 2014
RAQs: 100 Issues and Counting
Issue 100, December 2013
Overrange Flag Indicates Data Validity
Issue 99, November 2013
Design Tools and Support Communities Make Analog Fun, not Fearful
Issue 98, October 2013
EngineerZone Makes Getting Answers a Breeze
Issue 97, September 2013
Soft Clipping vs. Hard Clipping
Issue 96, August 2013
Issue 95, July 2013
Crystal Radio Sets and Op Amps—Both Can Detect RF Signals
Issue 94, June 2013
Input Magic—Differential Signals Allow Input Swing to Exceed Supply Voltage
Issue 93, May 2013
Multipliers and Modulators
Issue 92, April 2013
Noise Gain vs. Signal Gain
Issue 91, March 2013
Resolution vs. ENOB – Still Hazy After All These Years
Issue 90, February 2013
Electronics is Fun
Issue 89, January 2013
The Decline of Rounding—or How Significant is Significance?
Issue 88, December 2012
Apples and Oranges—Correlating Specifications Requires Common Test Conditions
Issue 87, November 2012
Current Transformers—and Vacuum Cleaners
Issue 86, October 2012
Great Expectations Come From Basic Understandings
Issue 85, September 2012
Driving Miss ADC
Issue 84, August 2012
Dual Op Amps and Double Agents
Issue 83, July 2012
Transformers: They’re Not All Boat Anchors
Issue 82, June 2012
Issue 81, May 2012
The Electromotive Force and Op Amps
Issue 80, April 2012
Nobody is Perfect – Not Even an Engineer!
Issue 79, March 2012
Considerations on High-Speed Converter PCB Design, Part 4: Plane Coupling
Issue 78, February 2012
Beware of big claims and large numbers.
Issue 77, January 2012
In and Out – or – Why Have a Capacitor?
Issue 76, December 2011
Issue 75, November 2011
Rotary Potentiometers: There Must Be a Better Option
Issue 74, October 2011
The Benefits of Ancient Logic
Issue 73, September 2011
Balancing Phase in High-Speed Converters
Issue 72, August 2011
Looking for savings in all the wrong places
Issue 71, July 2011
Do Something with that Unused Pin!
Issue 70, June 2011
Considerations on High-Speed Converter PCB Design, Part 3: The E-Pad Low Down
Issue 69, May 2011
A Foolish Question about Op Amps and Capacitors
Issue 68, April 2011
Measuring the DC Parameters of Op Amps
Issue 67, March 2011
Considerations on High-Speed Converter PCB Design, Part 2: Power and Ground Planes.
Issue 66, February 2011
Op Amp Dedicated Feedback Pin Helps Achieve New Levels of Performance.
Issue 65, January 2011
Oversampling and Undersampling
Issue 64, December 2010
Considerations on High-Speed Converter PCB Design, Part 1: Power and Ground Planes.
Issue 63, November 2010
Is amplifier headroom cramping your style?
Issue 62, October 2010
Issue 61, September 2010
Watch for Those Multiple Clocking Edges!
Issue 60, August 2010
Is Your Amplifier Disabled, or is it Merely Sleeping?
Issue 59, July 2010
How to Avoid Burning Cakes
Issue 58, June 2010
Keeping Your A/D Converter Clocks Jitter Free
Issue 57, May 2010
Amplifier, attenuator or both?
Issue 56, April 2010
Taming A/D Converter Power Supplies
Issue 55, March 2010
Don’t be Mean - be Root Mean Square!
Issue 54, February 2010
VFB or CFB that is the question!
Issue 53, January 2010
Bring on the Converter Noise! – Part 2
Issue 52, December 2009
Bring on the Converter Noise! – Part 1
Issue 51, November 2009
What’s the big deal about ABSOLUTE MAXIMUM RATINGS?
Issue 50, October 2009
What’s the (Converter) Frequency Kenneth?
Issue 49, September 2009
Some Chips Have Moving Parts!
Issue 48, August 2009
Which carries more weight, a datasheet or SPICE macromodel?
Issue 47, July 2009
What shall we do with an unused op-amp?
Issue 46, June 2009
Glass Diodes May See the Light — and Hum
Issue 45, May 2009
Keeping Common Modes Common
Issue 44, April 2009
Impedance Measuring Chip Offers Little Resistance to Applications
Issue 43, March 2009
Are Your Filters Filtering?
Issue 42, February 2009
What’s in Your Toolbox?
Issue 41, January 2009
How Big Is It?
Issue 40, December 2008
What The Heck Are Off-Amps?
Issue 39, November 2008
Single Supply Amplifiers—They Sound Simple…are they?
Issue 38, October 2008
Lock Down That Noise — Don’t Let It Escape
Issue 37, September 2008
The Difference Between Different Differential Amplifiers
Issue 36, August 2008
Stress Is Bad For You — and For Analog ICs
Issue 35, July 2008
A Capaciticectomy? Sounds Awfully Painful!
Issue 34, June 2008
Hysteresis Blocks Magic
Issue 33, May 2008
Political Correctness and Datasheets
Issue 32, April 2008
Too Hot or Too Cold May Be Just Right*
Issue 31, March 2008
Capacitive Sensors: Rugged Enough for the Real World?
Issue 30, February 2008
Half Full or Half Empty? Thoughts on Capacity.
Issue 29, January 2008
What's Your Amplifier's Febricity Due to Electricity?
Issue 28, December 2007
Resistors Have Hidden Depths
Issue 27, November 2007
Op-Amp Noise can be Deafening Too
Issue 26, October 2007
Resistor Noise can be Deafening, and Hard to Reduce
Issue 25, September 2007
Are leaky amps sinking your design?
Issue 24, August 2007
Should you butcher your circuit or your test gear?
Issue 23, June 2007
Things (animals and ADCs) are not always what they seem
Issue 22, May 2007
Breadboarding With Surface Mount ICs
Issue 21, April 2007
Igor, pass me some supply sequencers!
Issue 20, March 2007
Observing Maximum Ratings or How to Avoid Forecasts of Doom
Issue 19, February 2007
Just How Accurate was William Tell, Anyway?
Issue 18, January 2007
More Chips are Better than One (or the Benefits of Belgian Food)
Issue 17, December 2006
Replacing Optocouplers with Digital Isolators
Issue 16, November 2006
How to Age Gracefully and Avoid Sudden Death
Issue 15, October 2006
Why Good Engineers Use the Best Components
Issue 14, September 2006
Sigma Delta Converters are Not Really Hard to Understand
Issue 13, July 2006
How Not to Design Active Filters
Issue 12, June 2006
Comparators & Op Amps—May They Never Meet
Issue 11, May 2006
Digital Processing Does Not Always Rule
Issue 10, April 2006
Issue 9, March 2006
Happy Groundhog Day!
Issue 8, February 2006
It’s easy to drive an EE to drink—but what drives one to poetry?
Issue 7, January 2006
Issue 6, December 2005
Check the Bias Current
Issue 5, November 2005
Issue 4, October 2005
Isolating the Key Detail
Issue 3, September 2005
Slow “starting” ADCs
Issue 2, July 2005
Radio Frequency Interference (or how to get a free lunch at a very good restaurant)
Issue 1, June 2005