Questions tagged [photodiode]

A photodiode converts light to an electric current.

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Modelling Biased APD In Integrator Circuit

I want to model a biased APD (Avalanche Photodiode) whose current output feeds into an integrator. For the IC I will be using, TI recommends the following configuration for an unbiased photodiode. ...
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47 views

Photodiode Modelling

I want to model an Avalanche Photodiode (APD) in LTSpice. Is the below an appropriate representation?: simulate this circuit – Schematic created using CircuitLab If so, why is the diode ...
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36 views

IVC 102 Integrator IC - Photodiode Simulation Issues

I am designing a circuit that integrates a signal output from an avalanch photodiode. The component I am using is the ICV102U. Before purchasing the IC, I want to run a few simulations using LTSpice. ...
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78 views

Amplifier diode circuit

I've made a circuit with the schematic: The output pulses are only 1.5 \$\mu s\$ wide; does it make sense? I also want to get wider pulses, increased to 100 \$\mu s\$, is that possible? Is it ...
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76 views

Optical Receivers and Amplifiers

I have been doing some past papers for a university module I am studying. I am not from an electrical engineering background so don’t really know how to attempt the question attached. I would really ...
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62 views

Counting Hula Hoop

I'm trying to create a hula hoop that counts anything i'm throwing through it. To be clear i do not know electrical engineering. If I get a hula hoop, add reflective surface to the inside. Place a ...
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41 views

Photodiode pulse detect system

We have a laser signal detection system as shown in the figure below. In this system, we want to detect the incoming laser pulse. The MCU will detect the incoming pulse and perform its operations ...
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1answer
36 views

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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2answers
54 views

Arduino: convert analogRead from photodiode in a distance in cm or mm?

I am doing a very simple project on Arduino consisting of an IR LED and a photodiode that measure the distance from an obstacle. I am using an Arduino Nano BLE that has a 12-bit ADC converter. I am ...
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1answer
66 views

Map a specific photocurrent range from photodiode to ADC range 0 V .. 3.3 V

Problem Measure tiny current fluctuations in photo-diode. Lets say that photo-diode outputs \$2300\text{ nA} \pm 100\text{ nA}\$. Then that needs to be mapped to ADC. So \$2200\text{ nA} .. 2400\text{ ...
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36 views

Does the responsivity change with temperature of a pin photodiode?

I have a more fundamental question on which I can not find any answer, maybe there is some inherent understanding I am missing. I am currently trying to evaluate the temperature behaviour of a InGaAs ...
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72 views

How to configure / construct a CMOS sensor to act on changing signals only?

You all probably know how a CMOS sensor works, at least in general. In short, it consists of a lot of pixels (photodiode plus amplifier and so on), and each pixel is read out individually (different ...
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Photodiode square wave positive duty cycle lower and lower

I drive an IR LED with a 50% duty cycle square wave and receive its signal with a photodiode. If I take the photodiode farther and farther from the LED, the signal's positive duty cycle is lower and ...
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66 views

Gain of photodetectors

I found this in a lecture about "Optical Wireless Communications." It is slide 15. Does anyone have idea how gain was computed?
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37 views

What is the I_R current for this avalanche photodiode?

This is the datasheet of the APD I got. There's 'I_R' at test condition for breakdown voltage. What is this current I_R?
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APD (avalanche photodiode) responsivity problem

I'm experiencing a few problems with responsivity of APD (model: First Sensor AD500-8-S1). This is the circuit I tried to make. Just simply apply voltage (positive polarity) to the cathode for ...
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47 views

What is the role of capacitor of avalanche photodiode circuit?

I got few questions about apd circuit. There's a capacitor between the cathode and ground. What is the role of this capacitor? In picture, it say's 'min. 0.1uF, closest to APD', however, the ...
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I am trying to design a basic CMOS Image sensor

I am new to electronics so I might be doing some bad mistakes on my design but anyways, I'm trying to build a CMOS Image sensor using Proteus, and I couldn't find some basic tutorial to follow, Yet I ...
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1answer
114 views

Ways for comparing start and stop pulses in time of flight

I am using an LM358 as an astable multivibrator. I am pulsing an 850nm IR LED at 1 Hz. The IR LED has a carrier wave of 38 kHz generated by a 555 timer. I have a 38 kHz IR TSOP as receiver. It outputs ...
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64 views

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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2answers
82 views

Help identifying 3-pin open-collector photo-transistor-like component

Can someone help identify the 3 pin photo device (not the entire module) on this "Icstation 5V Light Sensor Module"? (may be same as this one It seems to act as a photo-transistor, but yet ...
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APD Module and A/D card

I want to make a LDV/PDPA device for measuring the diameters of droplets. For this device I need to use APD photodiode to gather the scattered light from droplets. I searched for PADs and found a ...
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59 views

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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111 views

Photodiode TIA circuit - filtering ambient light

In my lab, we are working on developing an open-source online biomass sensor. The basic idea is to shoot an IR light source to a colloidal solution and then measure the reflected light using a ...
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3answers
231 views

Altium Designer PCB Layout Review

I am very new to PCB design and have recently completed schematic capture and PCB layout of an optical detection circuit using Altium Designer. My custom PCB consists of a photodiode, transimpedance ...
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33 views

Finding Values For Cd and Ccm

When choosing an op amp for your system based on the system's required bandwidth, the value for Cin must be calculated for the required gain-bandwidth product. I understand that Cj is the junction ...
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36 views

Common Mode Input Capacitance

If I were to follow the same circuit diagram as provided in the image above, must I include Ccm myself? Or is this capacitance value apart of the op amp itself? Wondering the same for diode ...
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46 views

Input Source Capacitance Value for GBW Calculation

For the calculation of GBW product for a photodiode: Which diode capacitance value do I use for the input source capacitance (Cs)? I am having trouble understanding the difference between the 400pF ...
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49 views

Interfacing MCP3302 ADC with Arduino Micro SPI Help

I am very new to hardware design and am making an optical detection circuit using a photodiode. I simply need to interface with the photodiode and save the output voltage values on Arduino IDE ...
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1answer
76 views

Gain of transimpedance op amp

I am trying to calculate the gain-bandwidth product of a project where I am reading photodiode output current measurements. I aim to find an op-amp to buy to use as a transimpedance amplifier. The ...
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1answer
79 views

Choosing the Right Op Amp for Photodetection

I aim to use a silicon PIN photodiode to detect light emitted from a set of chemical reactions from a chamber. I am having trouble choosing an appropriate op amp to order to convert the photodiode's ...
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54 views

What is this Digilent Analog Discovery device doing in this experiment?

I'm a novice to electronics, and I was wondering if someone would clarify an experiment I just witnessed. A photodiode was set up to receive some signal. This signal is then read by a transimpedance ...
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371 views

Can I simply adjust the output power of these laser diodes to meet my specifications? If so, then what are the consequences of doing such a thing?

I need a CW laser diode, with an integrated photodiode, with wavelength around 800nm and power 1-1.5mW. Although I didn't find anything that exactly matching my specifications, I did find this from ...
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59 views

Using TSOP17 and 555 to measure distance

I am trying to design a simple circuit that measures distance. I will use an IR emitter and an IR reciever photodiode, and just measure the time between the moment the pulse was sent and when it was ...
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45 views

Identifying / distinguishing between PIN photodiode and avalanche photodiode

Is there any way to determine whether an unidentified photodiode is a regular PIN photodiode or is an avalanche diode? The photodiode is part of a small scintillation detector unit.
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53 views

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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2answers
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Does the photoelectric interaction occur mostly over the depletion zone of a photodiode?

It is important for some photodiodes like the PIN diode to have a large depletion zone. This is to achieve a large area that allows for conversion of photons to electron-hole pairs. Why does this ...
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173 views

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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318 views

Do AC input optocouplers require an ESD protection?

I intend on using a circuit I designed for detecting an AC input line for control purposes. One of the inputs will be accessed by third party users and a cable might be connected with a decent length(&...
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1answer
77 views

I want to register a small change of voltage of a photo sensing diode at bullet's speed

What I intend to do Estimate Accuracy of a Bullet Hit from the Bull's Eye: Use a row of light sensing diodes like BPW34 (or you suggest) spanning a feet vertically and horizontally or so with laser ...
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1answer
66 views

Are these scope traces normal for a reverse polarity LED hooked up to an NPN transistor?

I've been trying to make some cheap light sensors using some coloured LEDs and am using the schematic below. The idea is to hook up a bunch of LEDs (Red, Green, Blue etc.) to try and get an idea of ...
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How to calculate laser power on photodiode?

I am completely lost calculating the power of a laser diode and hope, that someone could help me. Here is my setup: OSRAM PL 520 (Type B1 = 50mW) Green Laser Diode OSRAM SFH 203 Photodiode The laser ...
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98 views

Design an RF amplifier for a photodiode

I've been asked to present a possible solution to design an optical system aimed at estimating the arrival time of the following light signal: $$s(t)=[\Sigma_{i=1}^∞rect(\frac{t-t_i}{T})]\cdot Acos(...
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2answers
47 views

Unclear block diagram of Hamamatsu's Hybrid Photo Detector

I am trying to understand what's happening in the block diagram of Hamatmatsu's Hybrid Photo Detector (HPD). The datasheet is available here. What exactly the two 2.5G Ohm of resistors doing there? ...
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5answers
105 views

Driving an LCD filter from a set of welding goggles - Optical modulator

I bought a pair of LCD welding goggles in the hope that I could re-purpose the switchable light filter for another project. Unfortunately, the circuit driving the LCD filter is way above my ability to ...
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2answers
127 views

Understanding the phototransistor

I am trying to learn how a phototransistor works, and I have made a schematic to show how I understand the photo-diode and NPN transistor to be linked in a phototransistor. I think that when light ...
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61 views

How to get the desired signal from a photodiode and phototransistor multisim?

The above is a visualization of an IR transmitter and receiver circuit I'm building. Sending a 2v and 1khz sine wave through a photodiode to a phototransistor. The figure above shows the outputs I ...
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1answer
102 views

Understanding how a NPN transistor works

I have been trying to understand how an NPN transistor works, specifically in the case of a photo-transistor. As far as I can tell, it should be something like this: I don’t understand how current ...
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1answer
94 views

Instability in photodiode amplifier circuit

I'm using a UV LED and a Schotky photodiode sensitive to UV light to get an estimate of the concentration of a vapor that passes through the space between the UV LED and UV diode, but I'm having ...
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1answer
53 views

Measurement of output current of a photodiode

I am a German student. My task is to conduct a characterization of a photodiode (KPEIMC-UDCOM by Kyosemi.) The photodiode will be illuminated by 850-1550 nm laser diodes. It would be good (but not ...

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