Two commonly asked questions when designing an operational amplifier into a new application are:
Most often these questions are asked in conjunction with other questions regarding the device’s various thermal resistance characteristics. These are part of a standard bank of questions used to gauge a device’s…
This technical article was updated on July 23, 2020.
When designing a high-performance data acquisition system, a diligent engineer carefully selects a precision analog-to-digital converter (ADC) and the additional components needed for the analog front-end conditioning circuit. After spending weeks designing, performing simulations and optimizing the schematic, the designer quickly puts board layout together to meet…
As a good, cynical and sarcastic analog engineer I am negative at times about a lot of things. However, from experience, I am here to tell you to never be negative about single supply comparators, especially if you want things to happen in a timely manner!
The TLV3701 is a “nanopower comparator” which uses a low quiescent power supply current of 560nA, typical. From the key specifications listed in Figure 1 we see the…
Whenever I review a schematic or a PCB layout for a younger engineer, I make a point to pick out items and simply ask them “why?” Why did you choose this component? Why did you place it here on the PCB? My point in asking these questions is that every design decision should have a valid reason that the engineer understands.
For example, a resistor in the feedback…
This is the final post a three-part blog series on electrical overstress (EOS) from amplifier expert Art Kay. Get more tips on how to avoid damage from EOS in the first and second installments of Art's series.
In the last electrical overstress blog we introduced the specifications for a Transient Voltage Suppressor (TVS). In this blog we will go through a step by step procedure for selecting the best TVS for your design…
The publication Planet Analog picked up one of my blog posts for publication to their readers. I invite you to go to their site for my full post.
The system ground return, or GND, symbol is often taken for granted when drawing schematics. GND symbols are placed all over the schematic with the assumption that the different GNDs will all be at the same electrical potential on the printed circuit board (PCB). In reality…
This technical article was updated on July 23, 2020.
Did you know that the input signal might affect how you select the best successive approximation register (SAR) analog-to-digital converter (ADC) for your application?
When we hear the word, “input,” there are several things that immediately jump into our heads – like frequency, amplitude, sinusoidal, sawtooth, etc. – all of which are relevant questions to ask when…
If you have a voltage divider where each resistor has 5 ppm/°C drift, what is the worst-case drift? That is the loaded question I posed to my colleagues recently (only after figuring out the answer myself, of course) while working on a low-drift current sensing reference design (TIPD156). The ‘obvious’ answer is 10 ppm/°C. It turns out to be just 5 ppm/°C, but only when the voltage divider ratio is…
This technical article was updated on July 23, 2020.
As you might know, both ENOB (“Effective Number of Bits”) and effective resolution are parameters that relate to an ADC’s resolution. Understanding how they differ, and deciding which one is more relevant, is a subject of much confusion and frequent debate among ADC users and Applications Engineers alike.
Which one do you think is more important?
…This is the second post a three-part blog series on electrical overstress (EOS) from amplifier expert Art Kay. Get more tips on how to avoid damage from EOS from the first and third installments of Art's series.
In the last electrical overstress blog we introduced the absolute maximum specification table and described how a series resistor can be used to protect the inputs from electrical overstress. Exceeding the power…
Figure 1
The diagram in Figure 1 is a 3-wire analog output module that uses a dual-channel DAC8562 digital-to-analog converter (DAC) to drive voltage and current output stages with the high-voltage, 36-V OPA192 operational amplifier (op amp).
The current output is a two-stage, high-side, voltage-to-current converter. The second stage – made up of amplifier A2, MOSFET Q2 and sense resistor RB – delivers the output…
If you follow this blog, you most likely have heard of TI Designs – Precision, our library of high-quality reference designs for precision applications. The first thing you’ll see on the TI Designs – Precision homepage is a graphic illustrating the three levels of these designs: Reference, Verified and CerTIfied. The first two levels – Reference and Verified – are straightforward, since most engineers…
This is the second post a three-part blog series on electrical overstress (EOS) from amplifier expert Art Kay. Get more tips on how to avoid damage from EOS from the second and third installments of Art's series.
I remember when I was in college and we somehow managed to get the 120V AC supply connected to the 5V microcontroller supply. The microcontroller exploded and little pieces…
In this three-part blog series I’ve been explaining how to select an op amp with sufficient bandwidth for your transimpedance amplifier circuit.
Catch up by reading part I. In part II I began a design example using this process to select an op amp to meet these circuit requirementsand determined the required op amp bandwidth is 5.26MHz.
Table 1: Example performance…
In my previous post I introduced the first two steps of a three step process for calculating the required op amp bandwidth for your transimpedance amplifier. In this post I’ll explain the final step and introduce a design example using this process.
Step 3: Calculate the required op amp gain bandwidth product.
A basic stability analysis will reveal the logic behind this step…
Join me for the first in a three part series...
The transimpedance amplifier is a common op amp application with an output voltage that depends on the input current and a feedback resistor:
Quite often I see this circuit used to amplify the output current of a photodiode as shown in Figure 1. Almost all transimpedance amplifier circuits require a feedback capacitor (CF) in parallel with the feedback resistor to maintain…
Last year, my colleague Tony Calabria and I brought the DAC Essentials blog series to Analog Wire. In the series, we discussed the static and dynamic specifications of precision digital-to-analog converters (DACs), precision DAC architectures, and DC error calculations.
This year on The Hub, we’re taking our writing to the next level with application-based follow ups to DAC Essentials, starting with a “mini-series” of…
Anyone who works with modern single-channel operational amplifiers, op amps, in their analog circuit designs are familiar with the 5 active device pins; the two inputs, the two supply pins and the output. These five pins accommodate the numerous applications where we apply op amps.
Following them is the next group having a sixth active pin function. Most often that additional pin…
As a newly hired employee recently out of college, previously known as “John the intern”, I thought my learning days were over. However, I quickly found out that is not the case and had a lesson on electro-static discharge (ESD) diodes of a device and the unintended effects they may cause in an application.
I needed to do some testing on the OPA192, so I grabbed my circuit…
A few years ago, I took a short boat tour off the coast of Hawaii. As Murphy's Law would have it, our ship was hit by a major typhoon. It seemed like the typhoon lasted for an eternity and when it was over we found ourselves washed up on a deserted tropical island. Unfortunately, our GPS and ship-to-shore radio was destroyed during the typhoon. We had no means of communication to the outside world and we didn’t even…
My birthday is this month; every year I remind my friends how much engineers HATE surprises. Whether it’s a surprise in our social lives or a surprise in a project, anything unexpected is unwelcome. In analog circuits, a very unwelcome surprise is the noise produced by active filter circuits. After all, active filters are supposed to remove noise!
All active circuits produce…
“Hey! Turn it down!”
You’ve probably heard these words at some point, especially if you’re like me and enjoy listening to music LOUD! If you decide to oblige and actually “turn it down” then what must you do? Reach for the volume control, of course!
What is a volume control? Put simply, it’s a circuit which attenuates the amplitude of an audio signal. Usually the desired behavior…
Calculating resistor self-heating. It’s a fairly fundamental concept that is often unfamiliar to, or overlooked by, many engineers.
I was reminded of its importance while explaining the theory behind a precision resistance temperature detector (RTD) acquisition system I recently designed. The design is featured in TI Designs – Precision reference design TIPD152. In the design, simplified in Figure 1, the errors…
My esteemed colleague, John Caldwell (not to be confused with ‘John’ the intern), authored a couple excellent blogs about instrumentation amplifier (INA) power supply and common-mode rejection ratio (PSRR & CMRR). (See “Dealing with rejection: Instrumentation amplifier PSRR and CMRR,” Part I and Part II)
He correctly noted that the CMRR & PSRR performance of most INA devices changes with gain…
Some of the most frequently asked questions we get in the Precision Amplifiers forum here in the E2E Community™ have to do with an IC’s long-term stability of various parameters. Nothing in nature is static, and the datasheet parameters are no exception.
Over time, semiconductor material doping levels, as well as physical stress exerted by the package on the die inside, undergo changes that lead to shifts in…
