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Amplifier Circuits:  Operational
Operational Amplifiers:  #'s - A        B - C      D - K       L - N       O       P - S        T - Z 

Amplifier -- Main Page

Last Updated: October 18, 2017 05:04 AM

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Balanced Frequency Converter (Suitable for Frequencies up to 50kHz) -  This circuit takes advantage of aliasing that occurs in any time sampled system.  The output signal frequency is the difference in frequency between the input signal and the switch sampling rate.  A 24KHz input signal sampled at 25KHz will be converted to a 1KHz output signal.  In addition by using the LTC1992 fully differential __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Bandpass Filter (Single Op-Amp) -  A bandpass filter passes a range of frequencies while rejecting frequencies outside the upper and lower limits of the paSSBand.  The range of frequencies to be passed is called the paSSBand and extends from a point below the center frequency to a point above the center frequency where the output voltage falls about 70% of the output voltage at the center frequency. __ Designed by Bill Bowden

Basic logarithmic Amplifier using op-amp & NPN transistor -  Schematic only

Basic Op Amp Model -  One of the challenges of simulating opamp circuits is modeling the op amp itself.  How is that accomplished? There's a couple of ways.  You can create a circuit of many transistors, resistors and caps that closely replicate the internals of an op amp   (spice design)

Basic opamps -  The op-amp is basically a differential amplifier having a large voltage gain, very high input impedance and low output impedance.  The op-amp has a "inverting" or   (-) input and "noninverting" or   (+) input and a single output.  The op-amp is usually powered by a dual polarity power supply in the range of +/- 5 volts to +/- 15 volts.  A simple dual polarity power supply is shown in the figure below which can be assembled with two 9 volt batteries. __ Designed by YO5OFH, Csaba Gajdos

Battery Powered (Li-Ion) Platinum RTD Signal Conditioner with Curvature Correction -  The LT2078 is a micropower dual op amp in 8-pin small outline, standard surface mount package, and LT2079 is a micropower quad op amp offered in the standard 14-pin surface mount package.  Both devices are optimized for single supply operation at 5V.  ±15V specifications are also provided. __ Linear Technology/Analog Devices App Note, Mar 30th 2010

Bias Tee -  Schematic Only __ Designed by www.gbppr.org

Biasing Op-Amps into Class A -  "Class A" refers to configuring an amplifier so that its output devices remain turned on all the time.  This reduces thermal variation and eliminates crossover distortion, which makes the chip perform better.  To bias an op-amp into class A, you simply put a current source from the op-amp's output to one of the power rails.  Everything else is details.  This article is about those details __ Designed by contact me 2014 @ tangentsoft.com

Bidirectional Current Source -  The LT1990 is a differential amplifier with integrated precision resistors.  The circuit shown is the classic Howland current source, implemented by simply adding a sense resistor. __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Bipolar, Ground Referenced, Single-Ended Signal Interface to Unipolar, Differential Input ADC -  Differential amplifiers are useful for providing the input to a single supply differential ADC from a bipolar ground referenced input source.  All of the signal level shifting and gain requirements can be adjusted with external resistors. __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Bootstrapping Allows Single-Rail Op Amp to Provide 0V Output -  02/06/03 EDN-Design Ideas __ Circuit offers improved active rectificationMany single-supply-powered applications require amplifier-output swings within 1 mV—or even submillivolts—of ground.  Amplifier-output-saturation limitations normally preclude such operation.  Figure 1's power-supply bootstrapping scheme achieves the desired characteristics with minimal parts count __ Circuit Design by Jim Williams, Linear Technology Corp, Milpitas, CA

Brake Failure Indicator -  Do you want to get an early warning of brake failure while driving? Here is a brake failure indicator circuit that constantly monitors the condition of the brake and gives an __ Electronics Projects for You

Build an Op Amp with Three Discrete Transistors -  12/01/11  EDN-Design Ideas This simple ac-coupled design inverts, runs off a single supply, and is self-biasingYou can use three discrete transistors to build an operational amplifier with an open-loop gain greater than 1 million   (Figure 1).  You bias the output at approximately one-half the supply voltage using the combined voltage drops across zener diode D1, the emitter-base voltage of input transistor Q1, and the 1V drop across 1-MΩ feedback resistor R2. __ Circuit Design by Lyle Russell Williams, St Charles, MO; Edited by Paul Rako and Fran Granville

Circuit Fault Protection with Latching Load Disconnect & Early Warning Indication -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators.  Two versions of the LT6109 are available.  The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Circuit Fault Protection with Very Fast Latching Load Disconnect -  The LT6108 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and a comparator.  Two versions of the LT6108 are available.  The LT6108-1 has a latching comparator and the LT6108-2 has a non-latching comparator.  In addition, the current sense amplifier __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Circuit Forms Ideal Diode Function -  This circuit uses a low power op amp and a p-channel FET to form a diode function with a very low 0.05 volt voltage drop.  With the selected FET, the circuit can handle up to 2 amps of current.  Higher currents are possible with a FET with a lower channel. . . Circuit by David A. Johnson P.E.-January, 2008

Circuit forms industrial-grade digital potentiometer -  09/20/01 EDN-Design Ideas Both ac and dc motors in modern industrial systems often receive their control from PLCs(programmable-logic controllers] in a control room safely away from the process.  If an operator must manually set the motor speed while observing the process, the component of choice is usually an industrial-grade potentiometer __ Circuit Design by Phill Leyva, Maxim Integrated Products, Sunnyvale, CA

Circuit Provides Inverting/Noninverting Gain -  11/09/95 EDN-Design Ideas The amplifier in Figure 1a is a well-known circuit that provIdeas voltage gain of +1 or –1, depending on the logic voltage (0 or 5V) you apply to the MOSFET gate.  By adding one resistor (Figure 1b), the amplifier can provide gain of +AV or –AV with the same logic control.  The gain is ±R3/R2, and R1 is (R3R2)/(R3–R2.).  You need a driving source with low output impedance, and the input impedance of the circuit is different for the two states. __ Circuit Design by    Victor Koren, Orckit Communications Ltd  Tel Aviv, Israel

Circuit provides linear I-to-V conversion -  01/18/96 EDN-Design Ideas The circuit in Figure 1 provIdeas a 4to 20-mA voltage-to-current conversion for noise-immune data transmission in industrial data-acquisition systems.  The circuit supplies two voltages to the inverting input of the control amplifier IC1A.  The first voltage, from the follower IC1B, introduces an offset in the transfer function of the circuit __ Circuit Design by Jordan Dimitrov, N Pouskarov Institute, Sofia, Bulgaria

Circuit Yields Accurate Absolute Values -  07/05/01  EDN-Design Ideas The circuit in Figure 1 delivers the absolute value of the input signal with an accuracy better than 10 ppm of the full-scale range.  The circuit has low zero-crossing error.  You can use it as an asynchronous demodulator, as a source __ Circuit Design by Marco Pisani, Istituto di Metrologia G Colonnetti, Turin, Italy

Class a JFET Opamp Circuit -  First Generation design that means it is not our latest design __ Contact: info @ forsselltech . com

Classic High-Precision Low Side Current Sense -  This configuration is basically a standard non-inverting amplifier.  The op amp used must support common-mode operation at the lower rail and the use of a Zero-Drift type (as shown) provides excellent precision.  The output of this circuit is referenced to the lower Kelvin contact, which could be ground in a single-supply application. __ Linear Technology/Analog Devices App Note, Mar 31st 2010

C-Load Tm Op Amps Conquer Instabilities -  DN107)  Design Notes __ Linear Technology/Analog Devices

C-Load Tm Op Amps Tame Instabilities -  DN83 Design Notes __ Linear Technology/Analog Devices

Clock Timer -  With this simple clock-controlled timer, you will never again miss your favourite TV or radio programme.  The TV or radio will switch on automatically at the time preset by you and __ Electronics Projects for You

Collection of Crystal Radios -  Collection of Crystal Radio Circuits __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Common-Mode Rejection -  While real op amps do a fantastic job of rejecting voltages common to both inputs, it's not perfect.  A small output results from a change in input common-mode voltage.  What causes this output? Due to mismatching in the transistors and resistors of the input stage, the common-mode voltage produces a small differential error voltage at the input terminals.  Subsequently (spice design)

Controlled power supply increases OpAmps output voltage range -  03/15/07 EDN-Design Ideas External transistors and op amps increase the outputvoltage range of a precision op amp. __ Circuit Design by Yakov Velikson, Lexington, MA

Current Feedback Amplifier Do's & Don'ts -  DN46 Design Notes __ Linear Technology/Analog Devices

Current Source -  Getting optimum performance in certain applications requires that some components, sensors, DC motors, transistors, be driven or biased by a constant current.  We're mostly familiar with voltage regulators and their ability to maintain a constant voltage under varying current conditions.  In this application, your challenge is to provide a constant (spice design)

Current-source enables op Amp's output to go to ground -  5-Aug-04 EDN-Design Ideas The LM324 is a cost-effective choice for an op amp, especially when you need to apply ground-level inputs.  Although its output purportedly includes ground, its poor current-sinking capability limits the applications.  At output voltages lower than 0.5V, the op amp's sinking current ranges only from 2 to 100 µA __ Circuit Design by Frank Chan, Vancouver, BC, Canada

Operational Amplifiers:  #'s - A        B - C      D - K       L - N       O       P - S        T - Z 


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