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Proceedings ArticleDOI

A reconfigurable cyclic ADC for biomedical applications

TL;DR: A reconfigurable cyclic ADC that saves readout power and reduces data acquisition rate of analog to digital converter (ADC) and also reduces the digital data content is presented.
Abstract: Bio-signals such as electroencephalogram (EEG) contain low activity regions often called B-noise and high activity regions called active potentials. The high activity regions are more important as compared to their counterpart. In addition, the signals are considerably sparse in the low activity regions. Thus a full n-bit conversion of low activity samples into digital domain increases readout power and reduces data acquisition rate of analog to digital converter (ADC). To alleviate these problems, a reconfigurable cyclic ADC is presented in this paper. Input range and conversion cycles of the proposed ADC are varied according to the samples of the neural signal. The high activity region samples are resolved using conventional n-bits, however, the low activity region is resolved using less number of bits. This saves readout power and also reduces the digital data content. The proposed ADC is designed and fabricated in UMC 180 nm CMOS technology. The ADC operates at a sampling rate of 200 kS/s and consumes 61.8 µW of power. The chip occupies an area of 0.031 mm2. Using reconfiguration, the power saving of 28.6% is achieved compared to the conventional n-bit full conversion.
Citations
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Journal ArticleDOI
TL;DR: A power-optimized column-parallel cyclic ADC for CMOS image sensor readout circuits by separating the capacitor and bias current source and floating them in the circuit, which allows the ADC to reduce power consumption while maintaining a constant conversion rate.

4 citations

Journal ArticleDOI
TL;DR: This paper systematically reviews the recent progress of characteristics, applications, and optimizations of transistor amplifiers and typical filters in signal conditioning, and mainstream analog-to-digital conversion strategies.

2 citations

References
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Journal ArticleDOI
TL;DR: The theory of compressive sampling, also known as compressed sensing or CS, is surveyed, a novel sensing/sampling paradigm that goes against the common wisdom in data acquisition.
Abstract: Conventional approaches to sampling signals or images follow Shannon's theorem: the sampling rate must be at least twice the maximum frequency present in the signal (Nyquist rate). In the field of data conversion, standard analog-to-digital converter (ADC) technology implements the usual quantized Shannon representation - the signal is uniformly sampled at or above the Nyquist rate. This article surveys the theory of compressive sampling, also known as compressed sensing or CS, a novel sensing/sampling paradigm that goes against the common wisdom in data acquisition. CS theory asserts that one can recover certain signals and images from far fewer samples or measurements than traditional methods use.

9,686 citations


"A reconfigurable cyclic ADC for bio..." refers background in this paper

  • ...Later, sampling at a rate lower than Nyquist is proposed in [4], however, complex reconstruction makes it unsuitable for biomedical applications....

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Journal ArticleDOI
TL;DR: A wavelet electrocardiogram (ECG) data codec based on the set partitioning in hierarchical trees (SPIHT) compression algorithm is proposed and is significantly more efficient in compression and in computation than previously proposed ECG compression schemes.
Abstract: A wavelet electrocardiogram (ECG) data codec based on the set partitioning in hierarchical trees (SPIHT) compression algorithm is proposed in this paper. The SPIHT algorithm (A. Said and W.A. Pearlman, IEEE Trans. Ccts. Syst. II, vol. 6, p. 243-50, 1996) has achieved notable success in still image coding. The authors modified the algorithm for the one-dimensional case and applied it to compression of ECG data. Experiments on selected records from the MIT-BIH arrhythmia database revealed that the proposed codec is significantly more efficient in compression and in computation than previously proposed ECG compression schemes. The coder also attains exact bit rate control and generates a bit stream progressive in quality or rate.

521 citations


"A reconfigurable cyclic ADC for bio..." refers background in this paper

  • ...In [3], a wavelet based compression for physiological signals is presented....

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Journal ArticleDOI
TL;DR: An implantable microsystem capable of recording neural activity simultaneously on 64 channels, wirelessly transmitting spike occurrences to an external interface, and allows the user to examine the spike waveforms on any channel with 8 bit resolution is reported.
Abstract: This paper reports an implantable microsystem capable of recording neural activity simultaneously on 64 channels, wirelessly transmitting spike occurrences to an external interface. The microsystem also allows the user to examine the spike waveforms on any channel with 8 bit resolution. Signals are amplified by 60 dB with a programmable bandwidth from < 100 Hz to 10 kHz. The input-referred noise is 8 ?Vrms. The channel scan rate for spike detection is 62.5 kS/sec using a 2 MHz clock. The system dissipates 14.4 mW at 1.8 V, weighs 275 mg, and measures 1.4 cm 1.55 cm.

233 citations


"A reconfigurable cyclic ADC for bio..." refers methods in this paper

  • ...Digital conversion of the signals allows the implementation of digital signal processing techniques on the data to reduce communication cost [6], [7]....

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Proceedings ArticleDOI
01 Nov 2007
TL;DR: This paper presents a successive approximation register analog-to-digital converter (SAR ADC) design for bio-medical applications and an energy-saving switching sequence technique is proposed to achieve low power consumption.
Abstract: This paper presents a successive approximation register analog-to-digital converter (SAR ADC) design for bio-medical applications An energy-saving switching sequence technique is proposed to achieve low power consumption The average switching energy of the capacitor array can be reduced by 56% compared to a conventional switching method The measured signal-to-noise-and-distortion ratios of the ADC is 4692 dB at 500 KS/s sampling rate with an ultra-low power consumption of only 775-muW from a 1-V supply voltage The ADC is fabricated in a 018-mum CMOS technology

156 citations


"A reconfigurable cyclic ADC for bio..." refers background in this paper

  • ...Successive approximation register (SAR) based ADCs are widely used for digitization of neural signals as these ADCs are power efficient [8]....

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Journal ArticleDOI
TL;DR: An adaptive resolution (AR) asynchronous analog-to-digital converter (ADC) architecture is presented that overcomes the trade-off between dynamic range and input bandwidth typically seen in asynchronous ADCs.
Abstract: An adaptive resolution (AR) asynchronous analog-to-digital converter (ADC) architecture is presented. Data compression is achieved by the inherent signal dependent sampling rate of the asynchronous architecture. An AR algorithm automatically varies the ADC quantizer resolution based on the rate of change of the input. This overcomes the trade-off between dynamic range and input bandwidth typically seen in asynchronous ADCs. A prototype ADC fabricated in a 0.18 μm CMOS technology, and utilizing the subthreshold region of operation, achieves an equivalent maximum sampling rate of 50 kS/s, an SNDR of 43.2 dB, and consumes 25 μW from a 0.7 V supply. The ADC is also shown to provide data compression for accelerometer applications as a proof of concept demonstration.

138 citations


"A reconfigurable cyclic ADC for bio..." refers background or methods in this paper

  • ...Data compression is a powerful tool to reduce the energy and storage requirements by reducing the data content in many of the medical devices [1], [2]....

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  • ...Adaptive sampling is, therefore, preferred in sensing neural signals, where the ADC resolution is varied according to the feature of input signal [2]....

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