Solutions Search - Low Power Amplifiers (Is < 1mA)
Hybrid Wide Dimming Ratio Linear LED Current Controller Using LT8614 & LT3083/LT6015
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 ...
Op Amp Precision Positive & Negative Clipper using LT6015/LT6016/LT6017
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 ...
LTC2387 Drivers Part III: Trans-Impedance Amplifier/Driver
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 ...
Low Power, Precision Op Amp Simplifies Driving of MUXed ADCs
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 ...
Signal Conditioning for High Impedance Sensors
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 ...
Injection-Lock a Wien-Bridge Oscillator
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, ...
Positive to Negative Converter with Variable Output Using LTC3630 and LT6015/LT6016
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 ...
Paralleling Amplifiers Improves Signal-to-Noise Performance
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, ...
Micropower Op Amp Drives 8-Channel 18-Bit Simultaneous Sampling ADC without Compromising Accuracy or Breaking the Power Budget
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 ...
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 ...
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 ...
Precision Op Amp Enables Fast Multiplexing at Low Power
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 ...
Robust High Voltage Over-The-Top Op Amps Maintain High Input Impedance with Inputs Driven Apart or When Powered Down
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 ...
LTspice: Stability of Op Amp Circuits
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 ...
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