Questions tagged [transimpedance]

The transimpedance of a device relates the current through the input of the device to the voltage across the output of the device.

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Photodiode bias in TIA?

When I see TIA schematics, I can see either the photodiode to GND or against VCC. What is the difference?
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Photodiode circuit unstable measurements on MCU ADC

I'm working on a fluoresce detection circuit. I have a lot of unstable measurements on the output of my second amplifier with the ADC. With the multimeter I have stable measurements. How can I smooth ...
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Measuring <10 pA of photocurrent using transimpedance amplifier

I am working on a project that measures low intensity light. The photodiode I am using an OSD35-5T. This is a large surface area photodiode. The idea is that the large surface area would absorb/...
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Feedback resistor and capacitor calculation for transimpedance amplifier

I am designing a transimpedance amplifier using LTC6268-10 from Analog Devices. The photodiode that I use is S9055-01 from Hamamatsu and the laser source that I use has a power of 10mW with the ...
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Photodiode Current Calculation for Simulation

I am designing a transimpedance amplifier and was trying to simulate the circuit to study its characteristics. I came across this online design tool provided by Analog Devices that builds the ...
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Is this a transimpedance amplifier?

Help needed on the below image: is this considered a transimpedance amplifier? With the Vo of 3 V given, can I find out the current source current? Since this current source from 0:255 μA (28 bits), ...
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Current sense resistor vs transimpedance amp vs hall effect current sensor for instrumentation?

I'm using a photomultiplier tube; this creates a current output relative to the number of photons incident to it, on the magnitude of microamps. So, I need a precise and accurate way of measuring very ...
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High frequency photodiode laser receiver strange output

We've built this transimpedance amplifier circuit to receive 10kHz pulses from a laser. The laser is driven by a square wave signal generator and is pulsing correctly. We expected to see a square wave ...
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Understanding noise in transimpedance amplifier

So I've been studying on TIAs for the last days and understood everything except the term of "noise". Let's take this TIA as an example: https://www.ti.com/lit/ds/symlink/opa380.pdf?ts=...
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Benefits of Transimpedance amplifier with a non-ground reference

Regarding this question -> Transimpedance amplifier with a non-ground reference What are the benefits of having an ideal absolute static reference voltage instead of just simple GND on the non-...
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Transimpedance and resistor bias in IR transmitter

I've been studying the optical (photo-diode) transmitter and receiver circuit for a while. There's a case that I can't understand the difference. In the optical receiver bias circuit, what is the ...
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10 votes
7 answers
1k views

Transimpedance amplifier for very low currents

I am currently working on a project, which requires me to measure the very low currents (approximately in the range of 100 pA to 10 uA) from an electrochemical sensor. The sensor is kind of a new ...
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Multi stage & gain opamp output voltage issue

I am currently facing an issue with an opamp circuit. The design consists of a transimpedance amplifier followed by a buffer stage and then followed by 6 non inverting gain stages (each stage 4 times ...
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Weird DC Response in Photodiode TIA Circuit

I'm building a photodetector circuit designed to measure the amplitude of a 1 kHz signal. . I have reworked the feedback resistor (R2) to 383 kΩ and changed the bandpass filter to have a gain of 15. I ...
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What is the equation relating Vin and Vout on a 2-Port Network?

I was reviewing a paper, and I got stuck while trying to understand the analysis of the two-port network. This is the circuit below with the equation below it This is my attempt below, my knowledge ...
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Transimpedance (I to V) converter using op amp

I was reading about the I to V converter using an op-amp. Doesn't the addition of the \$R_{\text{L}}\$ resistor affect the \$I_{\text{R}}\$ current? Because the same current that flows through the ...
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Current feedback amplifier

I was wondering whether is it ok to connect a current feedback amplifier (CFA) after the TIA stage to obtain high swing and large bandwidth. I am not sure how to connect the CFA after the TIA stage.
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1 answer
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Calculate intensity from a photodiode using voltage

I am running a photodiode through an op-amp circuit (trans-impedance amplifier.) I have been told I should characterize this device. I'm assuming he means using the voltage I get at a given distance ...
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3 answers
317 views

Is there a current-to-voltage converter circuit for professional applications?

We want to measure the information from three sensors that generate current (4mA for the minimum value and 20 mA for the maximum). Obviously, a simple solution could be to use the classic current-to-...
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Transimpedance amplifier design advice

I'm working on a transimpedance amplifier for a phototransistor in order to create a sensor that counts objects falling down a pipe. This is the sensor: https://www.digikey.it/short/0vq01q7h Datasheet:...
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1 answer
63 views

Current to voltage circuit

I'm currently doing a project that consists of testing bio-implants to see if they are still good to use. For this, I have to measure the impedance of the implant from frequency starting at 10Hz to ...
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2 votes
1 answer
318 views

Small feedback capacitor in photodiode amplifier

I'm designing a transimpedence circuit with a photodiode. Op-amp: LTC6268 (GBW = 500MHz) Photodiode: SFH2700 A1 (C_j = 4.6pF, max current = 1.5uA) Required bandwidth: 2MHz Using the calculation from ...
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Transimpedance amplifier transient voltage issue

We have below transimpedance amplifier, I have below issues, would like to know if this is even fixable or could be reduced: When a large load turn on in main power supply of TLE2426 turns on cause ...
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3 votes
2 answers
285 views

Programmable gain Transimpedance amplifier for 4-5 decade resistance measurement using Pulse voltage/current

As you can see from my previous question, I am trying to measure resistance within the range of 200k-60 ohms (around 4-5 decades). I will be using a pulse (5us pulse width and 50ns each rise and fall ...
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transimpedance amplifier configuration in a polygraph circuit

I am working through an assignment to design a polygraph circuit which works off skin resistance and in the brief, it specifies that a transimpedance amplifier must be used. I have never used one of ...
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Layout suggestion for transimpedance amplifier guard

I want to know what is best way to layout a transimpedance amplifier circuit like below. We have amultiplexer that picks the gain resistor and a feedback capacitor. (I am not worried about VGND ...
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Transimpedance Amplifier Troubleshooting

I am trying to build a transimpedance amplifier (shown below) using the LT1077 Op Amp IC to amplifier a signal from the BPW34B photodiode by OSRAM. My feedback resistor is a value of 2.2k. From what I ...
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2 answers
736 views

Detect an IR signal with a photodiode to use it with a microcontroller

I am trying to detect an IR signal with a photodiode to connect it to my STM32F411 and use it as a trigger signal. The signal I send are two pulses at 500 kHz which looks like this: I am using a ...
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3 answers
183 views

Controlling for ambient temperature changes in a transimpedance amplifier

I'll start by saying I'm new to electronics, and have only minor working knowledge. I am designing a transimpedance amplifier to measure the opacity of a surface that is changing over time. The ...
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3 votes
1 answer
126 views

Long distance required between photodetector and TIA

I have a circuit that incorporates a 40 channel InGaAs (IR) photodetector array (https://www.hamamatsu.com/eu/en/product/type/G8909-01/index.html). I have a TIA design using a LTC6268-10 first stage. ...
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Please explain negative bias and "a stronger field to sweep carriers out of depletion"

I want to understand what a comment means, and I couldn't ask in a comment. In this question, someone asked why use an op-amp with a photodiode rather than just a resistor. The answers and comments ...
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2 answers
1k views

Guard Ring on a printed circuit board for a transimpedance amplifier

I'm trying to build a trans-impedance amplifier shown in the circuit below. However, with my op-amp of choice, the AD795, I'm a bit confused by their circuit board notes and how to implement them. The ...
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0 votes
1 answer
137 views

Applying a forward bias to a photodiode to shift output

I am using this TIA circuit and photodiode in photovoltaic mode. I'd like to modify the circuit such that at zero light a positive voltage is produced at Vout. And as more light falls on the ...
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2 votes
4 answers
454 views

Design of a simple transimpedance amplifier for large area photodiode

I'm a mechanical engineer, who has the luck to design an easy transimpedance amplifier circuit to convert the current of a photodiode to a voltage between 0 and 5V (without really knowing anything ...
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1 answer
450 views

LM324N transimpedance amp for photodiode: Too low output, smaller feedback resistor gives greater output, not lower

I'm trying to build an optical power meter using a photodiode in photoconductive mode and a LM324N OpAmp: simulate this circuit – Schematic created using CircuitLab However, the output voltage ...
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2 votes
5 answers
296 views

TIA Photodiode SFH7050

I'm working with SFH7050 chip, it contains 3 LEDs and a photodiode. The datasheet suggests the next circuit: But it doesn't mention how to calculate Rf nor Cf. Which values should I use and how are ...
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1 answer
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How to connect photo diode to trans impedance amplifier?

transimpedance example here I need to design a trans-impedance amplifier to amplify the signal from a photodiode to make a PPG sensor I need a signal to acquire from the wrist. photodiode I am ...
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Photodiode transimpedance amplifier with integrated filtering

In a previous question about transimpedance amplifier stability, one interesting suggestion was that instead of trying to do multiple stages of op-amps in order to provide equalization for my signal, ...
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1 vote
1 answer
340 views

Why do we need differential amplifier after Transimpedance amplifier?

I am implementing the circuit published in AN3025 Transimpedance Amplifier Design as shown below. When I am simulating this circuit, a few questions come to mind: Q1. Why do we need a differential ...
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2 answers
205 views

Transimpedance amplifier simulation acting weird

So, I have been trying to simulate this low input current transimpedance amplifier, but I am just not getting results I was expecting. So to explain the circuit in short, I will be working with ...
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2 answers
56 views

lower limit to lower feedback resistor value in a transimpedance amp?

The upper limit to the gain setting feedback resistor value in a transimpedance amp is dictated by op amp rail voltage but is there lower limiting factor for the value also? I changed this feedback ...
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1 answer
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How can I accurately and precisely measure current in a 110V AC circuit, with a 1kohm-50kohm load, using an oscilloscope?

I need to measure the electrical resistance of a volume of ground. To do this I need to cause a current to flow between two metal electrodes pushed into the soil (let's call them the "current" ...
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0 votes
1 answer
45 views

Transimpedence amplifier, higher output than expected

I am approaching now at LTSpice. My aim is to design a transimpedence amplifier in order to have V_output=I_input*1000.I mean,such an easy task. So I tried to run my simulation, also adding a ...
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0 votes
1 answer
151 views

Why is the resistance on my PCB low?

I am designing a PCB for a LED, photodetector (several different tried), TIA (OPA380), and linear regulator (LT3042 to reduce noise). It's on FR4 from OSHPark. When the LED is on the photodetector's ...
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1 vote
0 answers
120 views

Why would a common Gate MOSFET (instead of a resistor) reduce noise in a TIA?

simulate this circuit – Schematic created using CircuitLab I am reading a paper on TIA for optical receivers. On one of the improvements regarding the noise the writers replace the feedback ...
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3 answers
359 views

Transimpedance Amplifier and Photodiode for BFSK

I am working on my first transimpedence amplifier circuit and am having some trouble. I have am looking to reconstruct a BFSK signal modulated on an LED. The BFSK signal uses a 50kHz sine wave at 80mA ...
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0 votes
2 answers
275 views

Op amp output voltage swing vs noise

Staying within an op amp's specified output voltage range, how does a difference in output swing affect the op amp's noise applied to the output signal? Obviously by increasing gain, we amplify the op ...
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1 answer
553 views

Introducing SiPM Array to an Op-Amp

I'm working on a transimpedance amplifier circuit, but it appears that there are issues reading out a signal. The source is comprised of sixteen individual SiPMs in parallel with each other, ...
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3 votes
1 answer
308 views

Transimpedance Amplifier Gain Analysis

I'm trying to go through a mathematical gain analysis of a closed-loop transimpedance amplifier circuit, but I'm having issues trying to relate the block diagram to the actual circuit. simulate this ...
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5 votes
4 answers
2k views

Norton op-amps advantages

I have been reading about Norton operational amplifiers, I got a good idea of how they work, even at the transistor level, I understand that difference current input = voltage output. What I have been ...
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