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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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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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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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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2answers
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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2answers
64 views
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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2answers
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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1answer
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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2answers
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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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1answer
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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1answer
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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21 views
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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1answer
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.
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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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1answer
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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1answer
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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1answer
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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1answer
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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1answer
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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1answer
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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2answers
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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1answer
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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0answers
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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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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1answer
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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2answers
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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0answers
46 views
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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3answers
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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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 ...
