scholarly journals Different Analog to Digital Converters Architectures

2020 ◽  
Vol 9 (4) ◽  
pp. 1256-1263
Keyword(s):  
Signal To Noise Ratio ◽  
Sampling Rate ◽  
Digital Signal ◽  
Vital Role ◽  
Analog To Digital Converters ◽  
Signal To Noise ◽  
Analog To Digital ◽  
Differential Nonlinearity ◽  
Gain Error ◽  
The Comparative Study

A series of recent studies has indicated that a mixed signal device analog to digital converters used for the processing of information and play a vital role in wireless sensors, Digital signal processing, Biomedical devices, in communication, IOT and various other applications. Across this broad use they give the significance in designing. The paper represents the various parameters like speed, area occupied, power consumption, sampling Rate, precision, Signal to noise ratio, Signal to noise distortion ratio, resolution, linearity and conversion time with respect to its different types and broad application in the real world. It defines errors due to non – linearity of signals as Differential nonlinearity, Integral nonlinearity, gain error, quantization error, aliasing and offset error. It also gives the comparative study about ADCs.

scholarly journals Influence of Analog-To-Digital Conversion and Decimation Parameters on the Signal-To-Noise Ratio in the Radar Path

2021 ◽  
Vol 24 (6) ◽  
pp. 38-50
Author(s):  
S. R. Heister ◽  
V. V. Kirichenko
Keyword(s):  
Signal To Noise Ratio ◽  
Sampling Rate ◽  
Quantization Noise ◽  
Least Significant Bit ◽  
Signal To Noise ◽  
Analog To Digital ◽  
Noise Interference ◽  
Analog To Digital Conversion ◽  
Wide Range ◽  
Noise Ratio

Introduction. The digital representation of received radar signals has provided a wide range of opportunities for their processing. However, the used hardware and software impose some limits on the number of bits and sampling rate of the signal at all conversion and processing stages. These limitations lead to a decrease in the signal-to-interference ratio due to quantization noise introduced by powerful components comprising the received signal (interfering reflections; active noise interference), as well as the attenuation of a low-power reflected signal represented by a limited number of bits. In practice, the amplitude of interfering reflections can exceed that of the signal reflected from the target by a factor of thousands.Aim. In this connection, it is essential to take into account the effect of quantization noise on the signal-tointerference ratio.Materials and methods. The article presents expressions for calculating the power and power spectral density (PSD) of quantization noise, which take into account the value of the least significant bit of an analog-to-digital converter (ADC) and the signal sampling rate. These expressions are verified by simulating 4-, 8- and 16-bit ADCs in the Mathcad environment.Results. Expressions are derived for calculating the quantization noise PSD of interfering reflections, which allows the PSD to be taken into account in the signal-to-interference ratio at the output of the processing chain. In addition, a comparison of decimation options (by discarding and averaging samples) is performed drawing on the estimates of the noise PSD and the signal-to-noise ratio.Conclusion. Recommendations regarding the ADC bit depth and sampling rate for the radar receiver are presented.

Retinal Digital Image Quality Improvement as A Diabetes Retinopatic Disease Detection Effort

2020 ◽  
Vol 4 (2) ◽  
pp. 53-60
Author(s):  
Latifah Listyalina ◽  
Yudianingsih Yudianingsih ◽  
Dhimas Arief Dharmawan
Keyword(s):  
Image Processing ◽  
Diabetic Retinopathy ◽  
Image Quality ◽  
Digital Image ◽  
Signal To Noise Ratio ◽  
Histogram Equalization ◽  
Vital Role ◽  
Retinal Images ◽  
Signal To Noise ◽  
Noise Ratio

Image processing is a technical term useful for modifying images in various ways. In medicine, image processing has a vital role. One example of images in the medical world, namely retinal images, can be obtained from a fundus camera. The retina image is useful in the detection of diabetic retinopathy. In general, direct observation of diabetic retinopathy is conducted by a doctor on the retinal image. The weakness of this method is the slow handling of the disease. For this reason, a computer system is required to help doctors detect diabetes retinopathy quickly and accurately. This system involves a series of digital image processing techniques that can process retinal images into good quality images. In this research, a method to improve the quality of retinal images was designed by comparing the methods for adjusting histogram equalization, contrast stretching, and increasing brightness. The performance of the three methods was evaluated using Mean Square Error (MSE), Peak Signal to Noise Ratio (PSNR), and Signal to Noise Ratio (SNR). Low MSE values and high PSNR and SNR values indicated that the image had good quality. The results of the study revealed that the image was the best to use, as evidenced by the lowest MSE values and the highest SNR and PSNR values compared to other techniques. It indicated that adaptive histogram equalization techniques could improve image quality while maintaining its information.

scholarly journals A Statistic-Based Calibration Method for TIADC System

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Kuojun Yang ◽  
Shulin Tian ◽  
Peng Ye ◽  
Peng Zhang ◽  
Yuanjin Zheng
Keyword(s):  
Sampling Rate ◽  
Calibration Method ◽  
Wide Frequency Range ◽  
Accurate Estimation ◽  
Analog To Digital ◽  
Average Value ◽  
Gain Error ◽  
Sampling Points ◽  
Interleaved Adc ◽  
Time Interleaved

Time-interleaved technique is widely used to increase the sampling rate of analog-to-digital converter (ADC). However, the channel mismatches degrade the performance of time-interleaved ADC (TIADC). Therefore, a statistic-based calibration method for TIADC is proposed in this paper. The average value of sampling points is utilized to calculate offset error, and the summation of sampling points is used to calculate gain error. After offset and gain error are obtained, they are calibrated by offset and gain adjustment elements in ADC. Timing skew is calibrated by an iterative method. The product of sampling points of two adjacent subchannels is used as a metric for calibration. The proposed method is employed to calibrate mismatches in a four-channel 5 GS/s TIADC system. Simulation results show that the proposed method can estimate mismatches accurately in a wide frequency range. It is also proved that an accurate estimation can be obtained even if the signal noise ratio (SNR) of input signal is 20 dB. Furthermore, the results obtained from a real four-channel 5 GS/s TIADC system demonstrate the effectiveness of the proposed method. We can see that the spectra spurs due to mismatches have been effectively eliminated after calibration.

VCO-BASED CONTINUOUS-TIME SIGMA DELTA ADC BASED ON A DUAL-VCO-QUANTIZER-LOOP STRUCTURE

2013 ◽  
Vol 22 (09) ◽  
pp. 1340013 ◽  
Author(s):  
Z. T. XU ◽  
X. L. ZHANG ◽  
J. Z. CHEN ◽  
S. G. HU ◽  
Q. YU ◽  
...  
Keyword(s):  
Continuous Time ◽  
Signal To Noise Ratio ◽  
Quantization Noise ◽  
Cmos Process ◽  
Voltage Controlled Oscillator ◽  
Loop Structure ◽  
Signal To Noise ◽  
Sigma Delta ◽  
Analog To Digital ◽  
Sigma Delta Adc

This paper explores a continuous time (CT) sigma delta (ΣΔ) analog-to-digital converter (ADC) based on a dual-voltage-controlled oscillator (VCO)-quantizer-loop structure. A third-order filter is adopted to reduce quantization noise and VCO nonlinearity. Even-order harmonics of VCO are significantly reduced by the proposed dual-VCO-quantizer-loop structure. The prototype with 10 MHz bandwidth and 400 MHz clock rate is designed using a 0.18 μm RF CMOS process. Simulation results show that the signal-to-noise ratio and signal-to-noise distortion ratio (SNDR) are 76.9 and 76 dB, respectively, consuming 37 mA at 1.8 V. The key module of the ADC, which is a 4-bit VCO-based quantizer, can convert the voltage signal into a frequency signal and quantize the corresponding frequency to thermometer codes at 400 MS/s.

scholarly journals Spike initiation properties in the axon support high-fidelity signal transmission

2021 ◽  
Author(s):  
Mohammad Amin Kamaleddin ◽  
Nooshin Abdollahi ◽  
Stephanie Ratte ◽  
Steven A Prescott
Keyword(s):  
Pyramidal Neurons ◽  
Signal To Noise Ratio ◽  
Signal Transmission ◽  
Digital Signal ◽  
Axial Current ◽  
High Fidelity ◽  
Pass Filter ◽  
Analog To Digital ◽  
Spike Initiation ◽  
High Pass

The axon initial segment (AIS) converts graded depolarization into all-or-none spikes that are transmitted by the axon to downstream neurons. Analog-to-digital transduction and digital signal transmission call for distinct spike initiation properties (filters) and those filters should, therefore, differ between the AIS and distal axon. Here we show that unlike the AIS, which spikes repetitively during sustained depolarization, the axon spikes transiently and only if depolarization reaches threshold before KV1 channels activate. Rate of depolarization is critical. This was shown by optogenetically evoking spikes in the distal axon of CA1 pyramidal neurons using different photostimulus waveforms and pharmacological conditions while recording antidromically propagated spikes at the soma, thus circumventing the prohibitive difficulty of patching intact axons. Computational modeling shows that KV1 channels in the axon implement a high-pass filter that is matched to the axial current waveform associated with spike propagation, thus maximizing the signal-to-noise ratio to ensure high-fidelity transmission of spike-based signals.

scholarly journals A Survey of Analog-to-Digital Converters for Operation under Radiation Environments

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1694
Author(s):  
Ernesto Pun-García ◽  
Marisa López-Vallejo
Keyword(s):  
Ionizing Radiation ◽  
State Of The Art ◽  
Sampling Rate ◽  
Analog To Digital Converters ◽  
Electrical Performance ◽  
Multiple Characteristic ◽  
New Developments ◽  
Analog To Digital ◽  
Figures Of Merit ◽  
Performance Patterns

In this work, we analyze in depth multiple characteristic data of a representative population of radenv-ADCs (analog-to-digital converters able to operate under radiation). Selected ADCs behave without latch-up below 50 MeV·cm2/mg and are able to bear doses of ionizing radiation above 50 krad(Si). An exhaustive search of ADCs with radiation characterization data has been carried out throughout the literature. The obtained collection is analyzed and compared against the state of the art of scientific ADCs, which reached years ago the electrical performance that radenv-ADCs provide nowadays. In fact, for a given Nyquist sampling rate, radenv-ADCs require significantly more power to achieve lower effective resolution. The extracted performance patterns and conclusions from our study aim to serve as reference for new developments towards more efficient implementations. As tools for this purpose, we have conceived FOMTID and FOMSET, two new figures of merit to compare radenv-ADCs that consider electrical and radiation performance.

scholarly journals Analog to Digital Converters (ADC): A Literature Review

2020 ◽  
Vol 184 ◽  
pp. 01025
Author(s):  
Hemlata Dalmia ◽  
Sanjeet K. Sinha
Keyword(s):  
Signal Processing ◽  
Low Power ◽  
Communication Technology ◽  
High Performance ◽  
Reducing Power ◽  
Digital Signal ◽  
Analog To Digital Converters ◽  
Analog To Digital ◽  
Cmos Scaling ◽  
Analog To Digital Conversion

The signal processing is advancing day by day as its needs and in wireline/wireless communication technology from 2G to 4G cellular communication technology with CMOS scaling process. In this context the high-performance ADCs, analog to digital converters have snatched the attention in the field of digital signal processing. The primary emphasis is on low power approaches to circuits, algorithms and architectures that apply to wireless systems. Different techniques are used for reducing power consumption by using low power supply, reduced threshold voltage, scaling of transistors, etc. In this paper, we have discussed the different types and different techniques used for analog to digital conversion of signals considering several parameters.

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