Questions tagged [adc]

An ADC is an Analog to Digital Converter. This device converts analog signals into digital form. It is mainly used by the digital circuitry to take analog measurements.

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22 views

STM32F103 ADC Variable Outputs

I'm not sure the cause but I'm having troubles getting a consistent voltage reading from the ADC pin of my STM32F103(actual bluepill and not a knockoff). Here is the serial output from my board (each ...
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408 views

Why is resistor needed in ADC circuit

This figure shows an ADC. My question: Why there is resistor (R) connecting to inverting pin of each OPAMP. Are they really necessary? In my opinion, they can be removed because you will have to ...
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Why do I need to put a low pass filter in front of an analog to digital converter (ADC?)

Is the low pass filter in front of the ADC just to filter higher frequencies or does it serve another purpose? I am talking about the ADS8320 ADC.
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Trying to increase resolution of ADC using an op-amp

We currently have a circuit measuring a thermistor in a water tank, passing through a couple of voltage dividers and then plugging into an 12bit ADC which eventually interacts with a microcontroller ...
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62 views

Protecting ADC Input inrush current

I'm currently using a 5V current transducer that's connecting to an I/O device ADC input. I'm trying to protect my ADC input from going over 5V by using a zener diode . The reason this is coming about,...
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26 views

Improve range on a differential ADC

I'm using an MCP3425 ADC, it has differential inputs but I'm using it as single ended mode. The signal that I want to digitize comes from an integrator circuit (an op amp with a capacitor in its ...
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HX711 noise, but only in a specific environment

I'm working on a small project at my farm to automate vegetable weighting. The system consists of an STM32 MCU, some additional ICs (matrix decoder, parallel-serial converter for some push-buttons etc....
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Mysterious noise of a CAMAC based digitizer

I'm trying to find out the cause of noise of a CAMAC based digitizer, which converts analog signal to digital signal. It basically functions as an ADC. The input of the digitizer is connected to a ...
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What is the most problematic SAR voltage? [closed]

Mgnd is a NMOS. During the proccesing step, I need to keep Vgs<Vt to keep the charge. The SAR is 7 bit with a certain capacitance.The general formula for V+ (source of the MOSFET) is shown below. I ...
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46 views

Why is the timing diagram of combined SAR ADC more efficient?

In the timing diagram below we have one SAR sampling while the other is proccesing. If we have a stream of samples which is twice as fast then the rate of each SAR, given data stream of N+1,N,N-1,N-2 ...
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52 views

Source Impedance Consideration for ADC

I recently used accelerometer ADXL335 in my academical project, this sensor gives analog output. I interfaced this sensor with microcontroller PIC18F458 using ADC module. It was successfully ...
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39 views

Faulty MAX134CMH+D A/D Converter?

I have been trying to troubleshoot a problem with my Protek 506 DMM, and I think that the problem may lie within its MAX134CMH+D A/D Converter chip, named U2 on the attached schematic diagram. The DMM ...
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Why INL DNL analysis of ADC gets wrong with 00 logic value

bellow we have two cases of DNL INL analisys . the first one without 00 logic acts great the INL is the the sum of the previos DNL. In the second case when i include 00 logic and we have 4 members. ...
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what is the GBW link to convertion time of pipe line ADC

I need to connect the GBW concept and input output charging time R*C two combine them into total convertion time. In the system shown bellow We have 3 stages of pipeline ADC where each stage is as ...
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61 views

Using Window Function to calculate RMS

The code below is from this site: https://community.cypress.com/thread/51426 I'm trying to understand what is happening in that code. Do I really need double type variables? This code is implemented ...
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22 views

Why INL is not a sum of previos DNL

In the ADC I have 2 bit system and Vref=1V with actual voltage shown as shown bellow. I have transformed the actual into UNIFORM as shown bellow and i produced INL from it. Bu when i started to ...
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67 views

How to modify zeros and poles in a delta-sigma modulator loop?

In this specific case, I am modelling a delta-sigma analog-to-digital converter with a basic loop in which the output V is fed back with unity gain to be subtracted from the previously sampled input U ...
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35 views

Complete ADC SNR formula when signal is not full scale

I am very in pain to find a (any) paper giving more than the traditional SNR for full-scale wave sampled by ADC $$ SNR(Full Scale Waveform) = 6.02N + 1.76 (dB)$$ As far as I can remember if the signal ...
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54 views

What is full scale of flash ADC?

My input signal is a sine of amplitude 1 so the input ranges from -1 to 1 so the range is 2 (pk-pk.) On the other hand, the flash voltage divider ladder goes from 0 to Vref. Which one of the two ...
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38 views

Supplying NTC by different voltage from VCC

I would like the sense a material temperature that is located outside of panel. My NTC thermistor is 10meter far from my STM32 MCU based control board. I don't want to use VCC at outside of the panel ...
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19 views

Current sense driver feedback line

Is the current sense feedback dependent on how the driver is controlled, PWM or discrete signal. Will the reading on ADC input differ when controlled by PWM, as we have a duty cycle? For example if ...
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30 views

Maximising sensitivity of AC voltage measurement on top of DC voltage with Arduino ADC

I have: Single supply rail voltage (3.3) current sensing transformer that outputs an 1v pk-pk value at is max rated sensing current (10A). The Transformer biased at 1v DC in order to ensure that the ...
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what pipeline ADC power consumption when scaling

In a system of 10bit pipeline which consists o 1.5bit pipeline sections and the last section is a 4bit flash ADC. The first stage of pipeline consumes 20mW,the next stages where "scaled" to ...
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58 views

ATmega328P: Reading from ADCL make ADC stop conversion

I am using a simple code to read from ADC pin A0. When I read from ADCH and ADCL. The result is correct only once in the startup. When I change the analog value in A0, output from the ADC don't change ...
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Which InGaAs photodiode to use? How to connect it to ADC? Which ADC to use?

I want to create small and reliable device that could measure concentration of some substances in liquid using Beer–Lambert law. It will contain 4 LEDs (550, 650, 950 and 1550 nm ones), photodiode, ...
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31 views

ENOB and oversampling ratios for delta-sigma ADCs (in relation to CS5343)

I came across the CS5343 ADC the other day and was impressed with its specs (relative to its cost) but then became confused when I dug deeper and read the datasheet. It's nominally a 24-bit 96 kHz ADC,...
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54 views

An analog input card can convert a -10V to +10V signal into a digital value of 0-27648

An analog input card can convert a -10V to +10V signal into a digital value of 0-27648. What is the digital value if the input signal is 0V? digital output = (2^N * analog input voltage) / (reference ...
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37 views

Calculate current through a resistor attached to an ADC?

I have a resistor, R1 = 100 kΩ, connected between a: DAC PIN_1 outputting 1.34 V ADC PIN_2 At PIN_2 I measure 0.57 V. Can i model the circuit as:PIN_1 -- 100 kΩ R1 -- PIN_2 -- R_ADC -- GND? For V1 ...
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21 views

Switching logic for 2.5 bit pipeline ADC

Below we have 2.5 pipeline section, with the Vout Vin diagram. In the diagram we see 6 transitions. But in the circuit we see 3 MUX'es with 3 wires each going inside so there are 9 transitions. I can'...
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35 views

ADC Overrun with Multimode, Scan and timer-triggered configuration

I'm using the STM32F446VE with 3 ADCs. I have a 50 kHz PWM running and want 2 of the ADCs to measure 2 Channels synchronized with the 50 kHz PWM. To achive this I used the regular simultanuous dual ...
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56 views

Suitable op-amp and voltage regulator for 16-bit ADC

I would like to use the AD4008 16-bit ADC from Analog Devices to sample a load cell. I also need a linear regulator and driver amplifier and instrumentation amplifier. I am curious to know if these ...
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SAR adc oversampling SQNR

In sigma delta we have SQNR based On OSR. In SAR ADC I need to find the link between the number of bits(number of switches of SAR) and Its potential OSR and SQNR. The only thing i have in SAR is the ...
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37 views

DMA Continuous Request and Normal vs Circular Mode

In STM32CubeMx, when configuring the ADC with DMA I can enable DMA Continuous Requests and set the DMA in circular mode if I want to perform N conversion at time indefinitely, right? But, what if I ...
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83 views

The relationship between bit depth and SNR in ADC

An 8-bit audio signal has a theoretical maximum SNR of 48.16 dB (20log(2^8)). My question then would be, does this work in reverse, i.e. would an analogue audio (or video) signal with an SNR of <=...
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Do DSL / ADSL modems have an ADC with ~ 2 MHz sampling rate?

For fun and no real practical use, I'm trying to design a DIY modem that can transmit data over an audio line, like old 56k modems did. I'm studying how to pack bits of data efficiently in a 1k-15k ...
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What is INL and DNL value for this case

i am trying to recreate the calculation for INL and DNL for n=100 $$S_{avg}=0.091$$ $$INL=\frac{(V_{actual}-V_{uniform})}{S_{avg}}=\frac{(0.33-0.35)}{0.091}=-0.21$$ $$DNL=\frac{(V_{actual_{100}}-V_{...
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46 views

How to solve ADC measurement issue?

For a project, I am using the following circuit to detect the load3 change. With an 16-bit coulomb counter ADC I am measuring the current I. Using onboard Arduino Uno ADC I am measuring votage, V at ...
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140 views

SPI Communication with multiple slaves: Problem on MISO line when both slaves are connected

----SETUP DESCRIPTION---- I'm running SPI Master VHDL code on an FPGA (Spartan 6 - XC6SLX9-3TQG144) with 2 slaves (both ADC122S021). I have one main board onto which I connect the FPGA. The first ADC (...
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57 views

Understanding Dynamic Range in ADC

I am trying to understand dynamic range for ADCs and am a bit confused. I have seen two definitions (the second of which I don't fully undertand)... The logarithmic ratio in decibels of the maximum ...
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3answers
59 views

Visualising redundancy in a 1.5 bit pipeline ADC

In a pipeline ADC, we have redundancy where we increase number of levels to somehow more accurately measure the input and reduce the error. In the manual shown below we see a redundancy example from ...
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21 views

SAR ADC offset calculation

In the photo shown bellow we have a calculation for SAR ADC voltage NODE sighned as Vout. Without offset we have -Vin voltage from the sampling stage and the Vfs with capactior voltage divider (...
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47 views

Real-time vs Non-Real time ADC processing

What are the applications or Pros/Cons of using real-time vs non-real time when reading an ADC? For example, let's say you're reading a sine wave from a CT. As far as I know, if you’re processing in ...
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What is transfer function(z transform) of sigma delta MOD1

I am trying to figure out the development shown bellow of the SIGMA DELTA ADC transfer function. However the definition of Vref, and Vint are the same except the time if n-1 instead of n. very non ...
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43 views

Read voltage / tap into existing voltage divider circuit without affecting?

I'd like to unobtrusively read the voltage of a simple thermistor & voltage divider circuit. This is a hot tub/spa controller and it is using 5v -> 20k (R1) -> thermistor (R2) -> ground ...
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47 views

why SAR ADC charge sign is negative

In the formula shown bellow why the charge between V+ and GND is minus to the charge of Vref and V+ ? Thanks.
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why SAR ADC private case matches general formula

There is a gerenal formula for SAR ADC shown bellow. And there is a private case for 101. i tried to match this private case with the gerenal formula and used N=2^3=8 and X=3 But i dont understand why ...
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Why does quantization noise in ADC have such a wide bandwidth?

In the slide shown below by red arrow we have quantization noise up to fs/2, but why? From Nyquist fs=fb/2 for good sampling but why is there noise here noise up to fs/2? What is the logic ?
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Testing the accuracy of a PLC current input module - economical approach?

I don’t want to suggest a particular brand or model so to discourage a good universal approach. But let’s say the DUT here would be your typical industrial PLC module, a typical 4-20mA SAR ADC based, ...
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35 views

ESP32 using Arduino: Internal Pull-ups don't work on GPIO25 or GPIO32

I'm programming a custom ESP32 board using Arduino where GPIO25 and GPIO32 are connected to pogo pins via short 5mm traces and to nothing else. The goal is to poll for a short between them as part of ...
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93 views

Low side current sense output waveform

I am trying to build low side current sense amplifier for my motor drive (1 kW BLDC trapezoidal control.) Before that I get confused with the current waveform of BLDC drive in low side. My application ...

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