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Solutions Search - Precision Amplifiers (Vos<1mV, TCVos<2uV/c)

Low Noise, Precision Op Amp Drives High Resolution SAR ADCs

Erjon Qirko - Product Evaluation Engineer
Kris Lokere - Strategic Applications Manager
Nov 20th 2017
Design Note DN1039: Introduction The LT6018 is an ultralow noise (1.2nV/√Hz at 1kHz) operational amplifier with ultralow distortion (–115dB at 1kHz). It has a gain bandwidth product of 15MHz, maximum offset voltage of 50µV and a maximum offset voltage drift of 0.5µV/°C. This combination of features ...

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Reference Filter Increases 32-Bit ADC SNR by 6dB

Guy Hoover - Applications Engineer Sep 26th 2017
Design Note DN568: Introduction Attaining optimal SNR performance from an ADC isn’t just a matter of providing a low noise signal to the ADC’s input. Providing a low noise reference voltage is just as important. While reference noise has no effect at zero-scale, at full-scale any noise on the reference will be visible ...

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Converting a Low Distortion Single-Ended Sine Source to Fully Differential

Guy Hoover - Applications Engineer Sep 10th 2017
Customers looking for a way to evaluate ADCs with differential inputs will find themselves in need of a low distortion, low noise differential sine source. Single-ended sine sources can be obtained by building a simple Wien-bridge oscillator or by employing any of several readily available audio oscillators. Differential sine ...

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LTspice: Worst-Case Circuit Analysis with Minimal Simulations Runs

Joseph Spencer - Field Applications Engineer
Gabino Alonso - Strategic Marketing Engineer
Jun 8th 2017
When designing a circuit in LTspice, you may wish to assess the impact of component tolerances. For example, the gain error introduced by non-ideal resistors in an op amp circuit. This article illustrates a method that reduces the number of simulations needed, and as a result speeds your time to results. Varying a Parameter LTSpice ...

Blog Post LTspice 

 

Lower Power Op Amp: Low Noise Reference, Utility Sine Wave

Catherine Chang - Applications Engineer
Philip Karantzalis - Senior Apps Eng
Aaron Schultz - Applications Manager Signal Conditioning
May 22nd 2017
Design Note DN1042: Introduction Our op amp family has expanded with industryleading speed versus supply current. The LTC®6258/ LTC6259/LTC6260 family (single, dual, quad) provides 1.3MHz at a super low 20μA supply current, with 400μV maximum offset voltage and rail-to-rail input and output. In combination with a ...

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Lower Power Op Amp: Utility Sine Wave

Aaron Schultz - Applications Manager Signal Conditioning
Philip Karantzalis - Senior Apps Eng
Catherine Chang - Applications Engineer
May 22nd 2017
Design Note DN564: Introduction Our op amp family has expanded with industryleading speed versus supply current. The LTC®6258/ LTC6259/LTC6260 family (single, dual, quad) provides 1.3MHz at a super low 20μA supply current, with 400μV maximum offset voltage and rail-to-rail input and output. In combination with a 1.8V ...

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Low Power Op Amp: Low Power Filter, Headphone Driver Revisited

Aaron Schultz - Applications Manager Signal Conditioning May 18th 2017
Design Note DN563: Introduction A new family of op amps features industry leading speed versus supply current. The LTC6261/LTC6262/ LTC6263 family (single, dual, quad) provides 30MHz at a low 240μA supply current, with 400μV maximum offset voltage and rail-to-rail input and output. In combination with 1.8V to 5.25V supply, ...

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Hybrid Wide Dimming Ratio Linear LED Current Controller Using LT8614 & LT3083/LT6015

Tom Mosteller - Field Applications Engineer Oct 17th 2016
Many applications for LED illumination require wide dimming ratios. This can be accomplished simply via an adjustable current source as show below.  The current source can be varied by a number of different means, and a large LED current range can be achieved. The primary problem with this technique is that the power dissipation ...

Blog Post Circuit LTspice 

 

Op Amp Precision Positive & Negative Clipper using LT6015/LT6016/LT6017

Tom Mosteller - Field Applications Engineer
Aaron Schultz - Applications Manager Signal Conditioning
Oct 3rd 2016
It can be a challenge to match the voltage range of an analog signal to the input range of an analog to digital converter (ADC). Exceeding the ADC’s input range will give an incorrect reading, and if the input goes far enough beyond the power supply rails substrate currents can flow into the ADC which can cause latch up ...

Blog Post Circuit LTspice 

 

LTC2387 Drivers Part III: Trans-Impedance Amplifier/Driver

Derek Redmayne - Staff Scientist Sep 8th 2016
This is unabashedly a classic case of what marketing calls “a solution looking for a problem”. It is an example of how the full SNR of the LTC2387 may be realized for a real world signal. Most signals originating in low level circuitry, in sensors, or in the real world, will require significant gain to develop 8Vp-p ...

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Anti-Alias Filter for 24-bit ADC

Guy Hoover - Applications Engineer Aug 3rd 2016
For many ADC applications a simple RC filter at the buffer input will provide adequate anti-alias filtering. For applications that require a higher order filter an active filter is often used. The active component in that filter must have sufficient bandwidth, fast settling, low noise and low offset so that it doesn’t ...

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LTC6244 High Speed Peak Detector

Hassan Kelley - Field Applications Engineer
Gabino Alonso - Strategic Marketing Engineer
Aug 1st 2016
Introduction Peak detectors capture the extrema of the voltage signal at its input. A positive peak detector captures the most positive point of the input signal and a negative peak detector captures the most negative point of the input signal. Ideally the output of the peak detector circuit tracks or follows the input voltage ...

Blog Post Circuit LTspice 

 

Baseband Design Example for LTC5589/LTC5599 Low-Power IQ Modulator

Bruce Hemp - Applications Section Leader Jul 1st 2016
Introduction This basic low power modulator was described in the LT Journal Nov 2015 article. In this blog post, we will show how to: Use simulation to validate the filter design, and Reduce DC offsets by utilizing Differential Amplifiers for the baseband drive. Also shown are some miscellaneous tips to help complete ...

Blog Post Circuit LTspice 

 

How to Drive the LTC2387 (Part 1): Signal Applications to 5MHz that Require Low Inter-Modulation Distortion

Derek Redmayne - Staff Scientist May 13th 2016
The biggest challenge in driving a 15Msps, 18-bit ADC with an 8Vp-p input range is the lack of integrated amplifiers with adequate bandwidth, low noise, and the required output excursion. There are low-noise, high-BW amplifiers than can produce 2VPP. There are low speed amplifiers than can produce 8VPP. For low distortion beyond ...

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Low Power, Precision Op Amp Simplifies Driving of MUXed ADCs

Guy Hoover - Applications Engineer Oct 2nd 2015
Design Note 1034: Introduction The high speed op amps required to buffer a modern 16‑/18-bit analog-to-digital converter (ADC) typically dissipate as much power as the ADC itself, often with a maximum offset spec of about 1mV, well beyond that of the ADC. If multiple multichannel ADCs are required, the power dissipation can ...

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Signal Conditioning for High Impedance Sensors

Glen Brisebois - Applications Engineer - Signal Conditioning Sep 22nd 2015
Abstract Dealing with high impedance sources and maintaining high impedance inputs without compromising reliability has its own set of challenges. This article offers qualitative and quantitative discussions of issues associated what high impedence circuits, what types of sensors are high impedance, and what devices are available ...

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Injection-Lock a Wien-Bridge Oscillator

Glen Brisebois - Applications Engineer - Signal Conditioning Sep 22nd 2015
I recently had the opportunity to investigate a new micropower 6-MHz LTC6255 op amp driving a 12-bit, 250k sample/sec LTC2361 ADC. I wanted to acquire the FFT of a pure sinusoid of about 5 kHz. The problem is that getting the FFT of a pure sinusoid requires, well, a pure sinusoid. Most programmable signal generators, however, ...

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Positive to Negative Converter with Variable Output Using LTC3630 and LT6015/LT6016

Philip Lane - Field Applications Engineer
Gabino Alonso - Strategic Marketing Engineer
Sep 1st 2015
There was a window of time in the 1950s and early ’60s when negative voltage rails were commonplace, when germanium PNP transistors were prevalent—like those used in an old “transistor radio”, now worth a fortune on Ebay. Nowadays, NPN transistors are more prevalent, since they basically work ...

Blog Post Circuit LTspice 

 

Paralleling Amplifiers Improves Signal-to-Noise Performance

Kevin B. Scott - Senior Strategic Marketing Engineer Jul 9th 2015
Dealing with low amplitude signals can be challenging.  In order to differentiate between the low level signal and the noise contributed by surrounding circuitry, we typically use gain to amplify the signal above the noise floor.  However, a standard amplifier configuration multiplies the input signal, the input noise, ...

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Micropower Op Amp Drives 8-Channel 18-Bit Simultaneous Sampling ADC without Compromising Accuracy or Breaking the Power Budget

Guy Hoover - Applications Engineer Jun 23rd 2015
Design Note 541: Introduction The op amps used to drive 18-bit analog-to-digital converters (ADCs) typically draw as much supply current as the ADC itself, often with a maximum offset spec that is well above that of the ADC. If multiple ADC channels are required, the power dissipation from these drivers quickly rises to unacceptable ...

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Sometimes You Need a Little Gain Part 2

Guy Hoover - Applications Engineer Apr 28th 2015
Introduction Part 1 of "Sometimes You Need a Little Gain" dealt with a pseudo-differential ADC driver with gains of one to ten. This time a fully differential ADC driver, again with gains of one to ten will be described. First a brief recap on the LTC2373-18 SAR ADC and a description of the LTC6237 op amp which will be ...

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Sometimes You Need a Little Gain - Part 1

Guy Hoover - Applications Engineer Apr 9th 2015
Introduction The LTC2373-18 is an 18-bit, 1Msps, 8-channel SAR ADC with an integrated high performance reference and programmable sequencer. The LTC2373-18 can be configured to accept both pseudo-differential (unipolar and bipolar) and fully differential input signals. For best performance, an op amp should ...

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Paralleling Amplifiers Increases Output Drive

Apr 1st 2015
There are several circuit techniques that increase the output drive capability of an amplifier. One method uses external bipolar transistors as a push-pull circuit to provide additional drive. Another method uses two different amplifiers in a composite amplfier configuration as detailed in Application Note 21 to leverage ...

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Avoid Amplifier Output Driver Saturation When Using pA Bias Current Amplifiers with High Source Impedance Sensors

Jon Munson - Applications Engineer
Kevin B. Scott - Senior Strategic Marketing Engineer
Mar 26th 2015
Need for Low Bias Current Amplfiers When taking sensor measurements, the type of sensor excitation used varies greatly; it can be a DC signal, an AC signal, a voltage source, a current source or a pulsed source to name a few. When using current source excitation or when using a high impedance sensor, the amplifier's bias current ...

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Transimpedance Amplifier Noise Considerations

Feb 18th 2015
The LTC6268 and LTC6269 is a single/dual 500MHz FET-input operational amplifier with extremely low input bias current and low input capacitance. It also features low input referred current noise and voltage noise making it an ideal choice for high speed transimpedance amplifiers, CCD output buffers, and high-impedance ...

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Increase Amplifier Output Drive Using a Push-Pull Amplifier Stage

Feb 17th 2015
Many portable circuits require precision measurement capability along with low power operation to minimize current and battery drain. When searching for an amplifer with these requirements, it may be relatively easy to meet the low power and precision requirements, but the drive current may not be adequate for these low power ...

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Loop Gain and its Effect on Analog Control Systems

Simon Bramble - Field Applications Engineer
Gabino Alonso - Strategic Marketing Engineer
Jan 26th 2015
Abstract This article brings together the ideas of open loop gain, closed loop gain, gain and phase margin, minimum gain stability and shows how these parameters are interrelated in a feedback system. It examines loop gain in terms of a theoretical control system as well as practical electronic circuits, including linear regulators. Introduction Bob ...

Blog Post LTspice 

 

Precision Op Amp Enables Fast Multiplexing at Low Power

Kris Lokere - Strategic Applications Manager Jan 23rd 2015
Introduction If you are designing a system that measures a number of analog voltages, but not all at the same time, you can reduce downstream circuitry by multiplexing the measurements into a single output signal, then serially process and digitize the original voltage levels using shared components. The benefit is that the ...

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Robust High Voltage Over-The-Top Op Amps Maintain High Input Impedance with Inputs Driven Apart or When Powered Down

Glen Brisebois - Applications Engineer - Signal Conditioning Nov 5th 2014
Introduction Linear Technology’s Over-The-Top op amps have an input stage topology that allows them to operate closed loop well above the positive supply rail. The inputs remain high impedance when split apart in voltage and also when shut down or with complete loss of power supply. They are indispensable in robust ...

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Locating Shorts on Power Planes of Multi-Layer PCBs

Bob Smith - Sr Module Design Engineer Aug 7th 2014
Occasionally multi-layer PCBs arrive with power to ground shorts that are difficult to locate. Usually the response to questions about finding these shorts is to just “Hook it up to a 12V battery and find out where it smokes.” While this may work, it’s usually not desirable since the board will probably be ...

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LTspice: SAR ADC Driver Interface

Kris Lokere - Strategic Applications Manager Apr 3rd 2014
High-performance SAR ADCs can offer amazing dynamic range and linearity at faster and faster sample rates. But how do you design the amplifier and interface at the analog inputs? LTspice IV can help. This video shows how to use LTspice to simulate the analog input interface of high-performance SAR ADCs. We will look at charge ...

Blog Post Video LTspice 

 

Digital Gain Compression (DGC) for SAR ADCs

Mar 11th 2014
The LTC2378-20 offers a digital gain compression (DGC) feature which defines the full-scale input swing to be between 10% and 90% of the ±VREF analog input range. This feature allows the SAR ADC driver to be powered off of a single positive supply since each input swings between 0.5V and 4.5V as shown in the figure below. Needing ...

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DC Accurate Driver for the LTC2377-20 Achieves 2ppm Linearity

Guy Hoover - Applications Engineer Jan 10th 2014
Introduction As resolution and sample rates continue to rise for analog-to-digital converters (ADCs), the driver circuitry for the ADC analog input, not the ADC itself, has increasingly become the limiting factor in determining overall circuit accuracy. First, the driver circuitry must buffer the input signal and provide gain. ...

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LTspice: Stability of Op Amp Circuits

Kris Lokere - Strategic Applications Manager Nov 6th 2013
We all know that feedback circuits can oscillate. We may even know some tricks of how to fix it. But wouldn’t it be nice if our simulation tool could show us exactly what is happening, and why? This video illustrates how to use the .AC analysis to look at open loop gain and phase of operational amplifier feedback circuits ...

Blog Post Video LTspice 

 

Layout For Precision Op Amps

Glen Brisebois - Applications Engineer - Signal Conditioning
Jeremy Wong - Design Engineer
Sep 13th 2013
The incredible offset and drift performance of modern precision op amps can easily be degraded by poor PCB layout techniques.  By utilizing a few simple layout techniques, the performance of the IC can be maintained. Thermocouple Effects In order to achieve accuracy on the microvolt level, thermocouple effects must ...

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High Voltage CMOS Amplifier Enables High Impedance Sensing with a Single IC

Jon Munson - Applications Engineer Apr 1st 2013
Introduction Accurately measuring voltages requires minimizing the impact of the instrument connection to the tested circuit. Typical digital voltmeters (DVMs) use 10M resistor networks to keep loading effects to an inconspicuous level, but even this can introduce significant error, particularly in higher voltage circuits that ...

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Matched Resistor Networks for Precision Amplifier Applications

Tyler Hutchison - Signal Conditioning Design Engineer May 1st 2012
Introduction Some ideal op amp configurations assume that the feedback resistors exhibit perfect matching. In practice, resistor non-idealities can affect various circuit parameters such as common mode rejection ratio (CMRR), harmonic distortion and stability. For instance, as shown in Figure 1, a single-ended amplifier configured ...

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