Many newcomers to analog-to-digital converters (ADCs) wonder how to convert their ADC code to a voltage. Or perhaps their question is specific to the application, such as how to convert the ADC code back to a physical quantity like current, temperature, weight or pressure. In this two-part blog series, I’ll address how to perform this math conversion for various applications. In part 1, I’ll explain how to covert an ADC…
The world is a hazardous place, and electronic systems are just as susceptible to mechanical failures as they are to unseen electromagnetic radiation. Let’s take a look at how to protect circuit designs from some of these visible and invisible perils.
A world inhospitable to electronics
It isn’t enough that the complexity of systems is ever-increasing; designers…
Did you know that there are operational amplifiers (op amps) with a ground pin? If you’re an experienced analog engineer, you probably know that, but those who haven’t worked much with older op amps might be asking themselves, “What’s a ground pin?”
Integrated circuit (IC) manufacturers used to label the ground…
This post is co-authored by Bharath Vasan.
In part three of this five-part blog series, we introduced a simple control-loop model for distortion in an operational amplifier (op amp), repeated here in Figure 1. We also included a pop quiz that we’ll continue discussing in this post, so please read that installment first if you haven’t done so already. Everything we discuss…
This post is co-authored by Bharath Vasan.
Pop quiz! Take a look at the total harmonic distortion and noise (THD+N) curve in Figure 1. It’s for an OPA1688, a 36V, 10MHz audio operational amplifier (op amp), delivering a 1VRMS sine wave to several common headphone impedances. The distortion at high frequency is rising and is worse for low impedances.
Why?
Choose the…
This article was updated on August 28, 2019.
A very passionate young engineer at a leading programmable logic controller (PLC) manufacturer was designing a multichannel 24-bit analog input module that accepts inputs from high-impedance sensors. He selected a TI 24-bit delta-sigma analog-to-digital converter, the ADS125H02, a 5-V voltage reference and a TI precision…
We live in a time where you can summarize technological trends with one word: more. We demand more features, more integration, more efficiency, more everything. In TI’s precision digital-to-analog converter (DAC) world, we feel no differently – we too want to provide more in our devices to support engineers who are designing innovative products. Our latest “more” comes in the form…
This post is co-authored by John Caldwell.
In the first post in our “Amp up your cans” blog series, my colleague John Caldwell and I used a nominal value of headphone impedance to calculate the output voltage and current requirements of headphone amplifiers. The impedance of most headphones is not purely resistive, however. Headphones are notorious for being a difficult…
In my last blog, I described how a customer had been operating their op amp circuit with a power supply voltage level that was too high for the amplifier and the consequences of doing this. Recently, while meeting with other customers, I’ve had similar conversations about voltage that is too low and I want to share my advice to them in this blog post.
This may be surprising…
Applications engineers tend to overlook printed circuit board (PCB) layout during circuit design. It is often the case that a circuit’s schematic is correct, but does not work, or perhaps works with reduced performance. In this post, I will show you how to properly lay out an operational amplifier (op amp) circuit PCB to ensure functionality, performance, and robustness.
An intern…
This post is co-authored by Bharath Vasan.
When we set out to create an operational amplifier (op amp) for headphone applications (which became the OPA1622 op amp), one of the first questions we needed to address was just how much power headphones need.
Think of headphones and loudspeakers as a transformer that converts an input electrical power to acoustic output power. Like all processes…
** This is the last post in a three-part ENOB blog series that launched on Halloween. You can find part 1 and part 2 here if you missed it. **
Sheets of heavy rain pound the pavement outside.
Arcs of lightning crackle in the distance.
A shadow fills the doorframe.
The eyes glow red.
It moves forward, boots thumping menacingly.
“It’s the eyes!” PGA shrieks. “The eyes
I saw just before ENOB disappeared…
Have you ever evaluated the noise performance of an ADC and found that your measured performance differs from the specified performance given in the device datasheet? Achieving high resolution in a precision data-acquisition system requires some understanding of analog-to-digital converter (ADC) noise. It is important to know how the datasheet specifies noise performance and how external…
** This is the second post in a three-part ENOB blog series that launched on Halloween. You can find part 1 here if you missed it **
Drip … drip … drip …
Drip … drip … drip …
A broken bottle leaks
liquid off a table onto
the floor. The sound
shatters the quiet of the
room, each drip louder
than the last.
Drip … drip … drip …
Drip … drip … drip ……
This technical article was updated on July 23, 2020.
When designing a data acquisition system (DAQ) for processing AC signals, your test results may not meet your required specifications, mainly due to poor distortion performance. What should you do under these circumstances? You might check the signal source first, followed by the power supply, the printed circuit board (PCB) layout, and so on, but the issue still exists…
In my last post, I discussed two important characteristics of delta-sigma analog-to-digital converters (ADCs) that simplify the design of your anti-aliasing filter: an oversampling architecture and a supplemental digital decimation filter. The oversampling architecture places the Nyquist frequency further away from your signal bandwidth of interest, while the digital decimation filter attenuates most of the unwanted out…
It’s just one of those nights …
Cold. Quiet. Still.
The smell of rain is suffocating.
A faint flash in the distance, followed by a long, low rumble.
The storm’s coming …
… just one of those nights …
A night for the forgotten.
For the vengeful.
And the justified.
One of those nights.
A night to fear.
Devil’s Night...
No tricks. No treats. Just shadows and dread.
…A few years ago, a customer asked me a rather surprising question: “I realize I am exceeding the maximum supply-voltage rating, but how long will your OPA373 operational amplifier continue to operate if it is powered by a 12V supply?” The operational amplifier (op amp) in question has an absolute maximum supply rating of 7V.
I told him that it would only be a matter of time before he would begin to have field…
My previous posts discussed the basics of 4-wire transmitters and showed circuit-level design options for output and power-isolated 4-wire sensor transmitters. In this post, I’ll cover the final isolation configuration for 4-wire sensor transmitters – fully isolated – in which the sensor, power supply and output transmitter are all completely isolated from each other.
Figure 1 is a high-level block diagram…
The multiplying DAC (MDAC) is the precision digital-to-analog converter (DAC) architecture with the strongest DC specifications. These specifications are important for applications that demand high DC accuracy, including calibration as well as test and measurement. MDACs tend to have the lowest integral non-linearity (INL), which enables high accuracy.
Another advantage is that most MDAC devices feature an unbuffered…
My last post introduced the concept of signal aliasing and how it manifests itself in data-acquisition systems. When out-of-band signals alias into the passband, they overlap lower frequency content and mask the true signals you’re trying to measure. To help filter any signals beyond the bandwidth of interest, you can add an anti-aliasing filter just before the inputs of your analog-to-digital converter (ADC).
…President Ronald Reagan frequently said “trust but verify” when discussing U.S. relations with the Soviet Union. Some say it comes from a Russian proverb, “doveryai no proveryai.”
Trust but verify is exactly what you should do when using SPICE operational amplifier (op amp) macromodels. For op amp stability analysis in the AC domain, you need to verify that…
My previous posts discussed the basics of 4-wire sensor transmitters, along with a detailed design of an output-isolated sensor transmitter. Today, I’m discussing power-isolated 4-wire sensor transmitters.
First, let’s review the high-level diagram of the output-isolated transmitter (Figure 1) that I discussed in my last post. In this topology, the transmitter is isolated from the power supply and sensor…
Have you ever seen the wheels on a car actually spin backward while the car is moving forward? Barring an extreme stunt, I’ll bet you probably saw it in a car commercial. Have you ever wondered why?
Real life happens in continuous time, but a video camera can only record a limited number of frames per second. Each frame may capture the wheels in a different position, so depending on how many rotations the wheels…
In my last post, I discussed the basic structure of 4-wire sensor transmitters and how they differ from 2-wire and 3-wire sensor transmitters. In this post, I will discuss the construction of a locally powered output-isolated 4-wire sensor transmitter like the one shown in Figure 1. Locally powered 4-wire sensor transmitters are popular in applications where the wires must run long…
