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Solutions Search - High Speed Amplifiers (GBW > 50MHz)

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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Improving Linearity by Using Absorptive Filters

Clarence Mayott - Applications Engineer Mar 10th 2017
Introduction: When driving a direct sampling high speed ADC, the most likely place to degrade the performance is the interface between the final amplifier and the ADC. With any direct sampling ADC there will be nonlinear charge produced in the sampling process. This charge is reflected into the input network each time the sampling ...

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High Linearity, Low Noise LTC2387-18 Drivers for Sinusoidal Signals

Doug Stuetzle - Senior Analog Applications Engineer Jan 10th 2017
Introduction The LTC2387-18 is a high speed SAR (Successive Approximation Register) ADC suited for high linearity, low noise applications. This ADC is capable of sampling at up to 15Msps, which allows it to convert signals at frequencies of several MHz. It is well-suited to convert both pulsed and continuous signals in this ...

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LTC2387 Drivers Part II: Drivers for Imaging

Derek Redmayne - Staff Scientist Dec 8th 2016
A Driver for Imaging (short version) The circuit shown below works great. You should try it. This is intended for nominally 0-3V single ended or differential signals, from CCDs, CMOS image sensors, or other similar signal sources. As shown, SNR is 88 dB. With the AD8008, in place of U1, and a few other minor changes, it ...

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Tuned IF Amplifier Applications

John Chung - Applications Engineer Oct 21st 2016
Introduction The LTC6431-20 and LTC6433-15 are single-ended RF / IF gain block amplifiers that feature very high OIP3 with low noise and a gain of 20dB and 15dB respectively. The unique combination of high linearity, low noise and low power dissipation make this an ideal candidate for many signal-chain applications. These fixed ...

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Single-Ended to Differential Driver Circuit for the LTC2387-18 SAR ADC

Doug Stuetzle - Senior Analog Applications Engineer Sep 26th 2016
The LTC®2387-18 is a 15Msps, highly linear, low-noise SAR converter with differential inputs. The combination of excellent linearity and wide dynamic range makes this ADC ideal for high speed imaging and instrumentation applications. No-latency operation provides a unique solution for high speed control loop applications. ...

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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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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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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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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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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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 

 

Driver for 14-Bit, 4.5Msps ADC Operates Over a Wide Gain Range

Guy Hoover - Applications Engineer Apr 3rd 2014
Introduction The LTC2314-14 is a 14-bit, 4.5Msps, serial output ADC with an integrated high performance reference. The single-ended input of the LTC2314-14 is easy to drive and in many instances does not require a buffer. A driver, such as the LT6236 op amp, may be required for a signal that is small or has high output impedance. ...

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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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Generating a ±10.24V True Bipolar Input for an 18-Bit, 1Msps SAR ADC

Guy Hoover - Applications Engineer Dec 17th 2013
Introduction The LTC2338 is an 18-bit fully differential SAR ADC that is remarkably easy to drive. This 1Msps ADC operates from a single 5V supply and achieves ±4LSB INL maximum with –111dB THD and 100dB SNR. Its fully differential ±20.48V true bipolar input range minimizes the need for range scaling, and ...

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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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