Electrical Engineering Stack Exchange
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Questions tagged [adc]

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

ADC stands for Analog to Digital Converter, and, as the name suggests, it's used for converting analog signals (world is analog) into bits, to allow digital processing.

The main parameters that characterize an ADC are the resolution (in bits) and the speed of conversion. That is also the main tradeoff between fast ADCs, made for real-time control of quick signals, and precision ADCs, used for accurate conversions like audio applications. In general, faster and higher resolution ADCs are higher power than slower and lower resolution ones.

Types of ADCs include

  • Flash: Damn Fast™, but use a lot of chip real estate, therefore only low resolution
  • Successive Approximation
  • Dual-Slope and Multi-Slope
  • Delta
  • Sigma-Delta

Further reading:
Walt Kester - The Data Conversion Handbook (ebook)

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How to Convert 0 to 10V analog signal to 0 to 2.5V for ADC input?

I have an analog signal which ranges between 0V and 10V. I want to linearly scale it down to 0 to 2.5V for my ADC. I'm concerned that using a resistive voltage divider will affect signal quality. Is this true? If it's not true, what value…
lionheart
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ADC is detecting a sine wave as several clusters of points

I'm using an ADC (ADS4129) running at 125MSPS. I'm applying a 100kHz sine wave to a low pass filter (fc=15MHz). The ADC is being driven differentially, as intended. When probing the input signal with a scope I see a decent sinusoid. My problem is…
user264107
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What is a differential ADC?

How does a differential analog to digital converter differ from a regular ADC?
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Effective number of bits of 14-bit ADC

I have a 14-bit ADC. However, looking at the datasheet (see table 2 on page 5), the effective number of bits (ENOB) is always less than 12 bits. Why is my the DAC claiming to be a 14-bit ADC when it only has 12-bit accuracy? What is the point of…
Randomblue
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Voltage dividers and ADC's

I want to read a voltage from 0-30V with an MCU ADC which has a maximum input of 3V. Initially I thought of using a 100k-10k divider (so 33V translates to 3V) but according to the answers to ADC input impedance on MCUs, this will add a 3% error due…
Thomas O
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Use two ADC channels to increase resolution

I need to capture the waveform of a low-amplitude signal that sits on top of a slow-varying, higher-amplitude component. I'm thinking of using an ADC with two channels, and feed one of them with a low-pass filtered version of the signal and the…
DanW
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What is the purpose of ADC sampling time?

I am trying to understand the usage of ADC sampling time? The ADC I have has a programmable sampling time of 100nsec/500nsec and 1uSec. What is the primary use case of longer sampling time, why wouldn't you use 100nsec for every signal? [I also…
Ktc
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What would cause this kind of amplitude interference on my ADC recording?

I am using a 12-bit 6.4Mhz ADC to record a sensor reading. It's an ultrasound doppler system. A DAC is used to generate a TX frequency, that frequency is bounced off a moving target and received via an ultrasonic sensor. In my testing environment,…
stanri
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What are the units of the output of an ADC?

How would you write or label the output of an analog-to-digital-conversion? I don't seem to have a good grasp for the english when I try to write this out. counts? arbitrary units? For example, if I want to write this out as algebra or label in a…
tarabyte
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Protection of ADC inputs

I am using an ADC MCP3424. After breaking one of the ADC inputs, I was saw this thread: ADC input protection? I also read Microchip app note TB3013. Figure 3 in particular: The ADC's analog inputs need to be clamped at ± 0.3V of the supply…
EmbSysDev
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Analog-Digital converter's LSB formula

What is the correct definition of the LSB voltage for an analog to digital converter? I have found two formulas: LSB = FS / (2N) LSB = FS / (2N - 1) N ... resolution in bits of the ADC. FS ... Full scale input range Has this anything to do with the…
Don
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Shrinking an input signal for the ADC

I'm looking to sample a 0 to +15 V analog input signal, and it is not sinusoidal, rather it is impulse driven. I don't need to sample at a high rate (< 1kHz), but I need to sample over the full range of the signal. The way I see there are two…
Dr. Watson
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High precision ADC board design

I am planning to make some calibration module designs using the ADS8691IPW ADC from TI. I need 4 channels of separate ADC lines. I am planning to use separate 4 isolated supply channels. I designed schematics for one ADC channel. I used an input…
ARAVIND V.P
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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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How to find the dynamic range of ADC?

I bought a Analog to Digital Converter but did not gave much attention to Dynamic range. The resolution is 12 Bit. Minimum input voltage is 0V and maximum is 5V. The problem is I don't have the datasheet and want to know how can I find the Dynamic…
Lifestohack
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