scholarly journals Photodetector resistant to background light noise with extended dynamic range of input signals

2021 ◽  
pp. 3-8
Author(s):  
V. M. Lipka ◽  
V. V. Ryukhtin ◽  
Yu. G. Dobrovolsky
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Modulation Frequency ◽  
Low Frequency ◽  
Gain Control ◽  
Ambient Air ◽  
Frequency Range ◽  
Background Light ◽  
Useful Signal ◽  
Extended Dynamic

Measurement of periodic optical information signals in the background light noise with a photodetector with extended dynamic range is an urgent task of modern electronics and thus has become the aim of this study. To increase the dynamic range of the photodetector, a new version of the automatic gain control (AGC) circuit has been developed, which consists of an AGC controller, an output photodetector amplifier and an AGC detector. The authors measured the dynamic range of the photodetector when receiving optical radiation with a wavelength of 1064 nm in the power range from 2.10–8 to 2.10–5 W at a modulation frequency of 20 kHz with the AGC on. Under these conditions, the dynamic range of the photodetector was found to be up to 67 dB. If the AGC was off, the dynamic range did not exceed 30 dB. Thus, the study made it possible to create a photodetector with an extended dynamic range up to 67 dB based on a new version of the AGC circuit. The design of the photodetector allowed choosing a useful signal of a particular modulation frequency in the frequency range from 3 to 45 kHz and effectively suppresses the frequencies caused by optical interference in the low frequency range from the frequency of the input signal of constant amplitude up to 3 kHz inclusive. This compensates the current up to 15 mA, which is equivalent to the power of light interference of about 15 mW. Further research should address the issues of reliability of the proposed photodetector design and optimization of its optical system. The photodetector can be used in geodesy and ambient air quality monitoring.

scholarly journals 14.85 µW Analog Front-End for Photoplethysmography Acquisition with 142-dBΩ Gain and 64.2-pArms Noise

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 512
Author(s):  
Binghui Lin ◽  
Mohamed Atef ◽  
Guoxing Wang
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Low Noise ◽  
Total Power ◽  
Cmos Process ◽  
Control Block ◽  
Silicon Area ◽  
Front End ◽  
Analog Front End

A low-power, high-gain, and low-noise analog front-end (AFE) for wearable photoplethysmography (PPG) acquisition systems is designed and fabricated in a 0.35 μm CMOS process. A high transimpedance gain of 142 dBΩ and a low input-referred noise of only 64.2 pArms was achieved. A Sub-Hz filter was integrated using a pseudo resistor, resulting in a small silicon area. To mitigate the saturation problem caused by background light (BGL), a BGL cancellation loop and a new simple automatic gain control block are used to enhance the dynamic range and improve the linearity of the AFE. The measurement results show that a DC photocurrent component up-to-10 μA can be rejected and the PPG output swing can reach 1.42 Vpp at THD < 1%. The chip consumes a total power of 14.85 μW using a single 3.3-V power supply. In this work, the small area and efficiently integrated blocks were used to implement the PPG AFE and the silicon area is minimized to 0.8 mm × 0.8 mm.

Determining the depth of surface charging layer of single Prussian blue nanoparticles with pseudocapacitive behaviors

2021 ◽  
Author(s):  
wei Wang ◽  
Ben Niu ◽  
Wenxuan Jiang ◽  
Mengqi Lv ◽  
Sa Wang
Keyword(s):  
Prussian Blue ◽  
Electrochemical Impedance ◽  
Modulation Frequency ◽  
Low Frequency ◽  
Frequency Range ◽  
Force Microscopy ◽  
Surface Charging ◽  
Prussian Blue Nanoparticles ◽  
Unit Cells ◽  
Pseudocapacitive Behavior

Abstract Based on the dependence of the light scattering intensity of single Prussian blue nanoparticles (PBNPs) on their oxidation state during sinusoidal potential modulation at varying frequencies, we present an electro-optical microscopic imaging approach to optically acquire the Faradaic electrochemical impedance spectroscopy (oEIS) of single PBNPs. Frequency analysis revealed typical pseudocapacitive behavior with hybrid charge-storage mechanisms depending on the modulation frequency. In the low-frequency range (0.04–1 Hz), the optical amplitude was inversely proportional to the square root of the modulation frequency (i.e., ∆I ∝ f− 0.5; diffusion-limited process), while in the high-frequency range (1.25–100 Hz), it was inversely proportional to the modulation frequency (∆I ∝ f− 1; surface charging process). The contribution of each process was, therefore, determined and quantified using oEIS at the single-nanoparticle level. Because the geometry of single cuboid-shaped PBNPs can be precisely determined by scanning electron microscopy and atomic force microscopy, oEIS of single PBNPs allowed the determination of the depth of the surface charging layer, revealing it to be ~ 2 unit cells regardless of the nanoparticle size.

An Optimized Design Strategy for the Hardware Implementation of the Hearing Aid Algorithms

2015 ◽  
Vol 719-720 ◽  
pp. 548-553
Author(s):  
Feng Guo ◽  
Shan Shan Yong ◽  
Zhao Yang Guo ◽  
Xin An Wang ◽  
Guo Xin Zhang
Keyword(s):  
Hardware Implementation ◽  
Dynamic Range ◽  
Automatic Gain Control ◽  
Hearing Aid ◽  
Gain Control ◽  
Design Strategy ◽  
Optimized Design ◽  
Wide Dynamic Range ◽  
Dynamic Range Compression ◽  
The Common

In this paper, a new design strategy for the hardware implementation of hearing aid algorithms is proposed. Two familiar hearing aid algorithms—Wide Dynamic Range Compression (WDRC) and Automatic Gain Control (AGC)—are implemented in one circuit as an example. By putting the common arithmetic procedures into common module, the operation units can be used repeatedly. In this way, the area and power consumption are visibly reduced.

Low Frequency Electrochemical Accelerometer with Low Noise Based on MEMS

2012 ◽  
Vol 503 ◽  
pp. 75-80 ◽  
Author(s):  
Wen Tao He ◽  
De Yong Chen ◽  
Guang Bei Li ◽  
Jun Bo Wang
Keyword(s):  
Early Warning ◽  
Dynamic Range ◽  
Low Frequency ◽  
Inertial Mass ◽  
Low Noise ◽  
Fabrication Process ◽  
Frequency Range ◽  
Wide Dynamic Range ◽  
Geological Disaster ◽  
Excellent Property

Petroleum prospecting and early warning of some geological disaster increasingly depend on the accelerometers which can detect vibrate of frequency below 1Hz, but it’s embarrassing that accelerometers based on Si or SiO2 structure make an awful performance in this frequency range. Electrochemical accelerometers were developed in 1990s. With fluidics to be inertial mass, electrochemical accelerometer not only show an excellent property in low frequency, but also has a wide dynamic range. However, traditional fabrication process of electrochemical accelerometer is rather complex and can’t eliminate the noise due to the inconsistency and asymmetry of electrodes. To solve these problems, a scheme based on MEMS is proposed here, including design, fabrication and package. Properties of electrochemical accelerometer (EAM) are tested in two conditions at last.

Servo systems for Cerenkov light receivers

1968 ◽  
Vol 46 (10) ◽  
pp. S1118-S1121 ◽  
Author(s):  
J. H. Fruin ◽  
J. V. Jelley
Keyword(s):  
Dynamic Range ◽  
Pulse Height ◽  
High Energy ◽  
Control Factor ◽  
Frequency Range ◽  
Servo Systems ◽  
Background Light ◽  
Discrimination Level ◽  
Filament Lamps ◽  
Cerenkov Light

The paper describes a variety of servo systems which have been developed for use with Cerenkov light receivers. Particular attention is devoted to the problem encountered in the high-energy γ-ray astronomy application, namely that the total background light within the field of view should be maintained constant during individual drift-scans or on–off comparison runs.Both filament lamps and midget fluorescent indicating lamps have been used as the active elements in the servo loops, and the systems have been operated either (a) from the phototube current or (b) from the counting rate at a selected pulse-height discrimination level. The characteristics of the various systems are discussed, in relation to the control factor, dynamic range, and stability. One of the systems developed was fast enough to respond to stellar atmospheric scintillations in the frequency range d-c. to 1 kHz.A servo system of a different type is also described, in which the sensitivity rather than the background light can be stabilized; in this way it was found possible to accommodate large variations of background light over long periods.

scholarly journals A 23-GHZ BANDWIDTH AUTOMATIC GAIN CONTROL AMPLIFIER WITH WIDE DYNAMIC RANGE FOR HIGH SPEED COMMUNICATION

2013 ◽  
Vol 142 ◽  
pp. 261-273
Author(s):  
Bo Zhang ◽  
Yong-Zhong Xiong ◽  
Lei Wang ◽  
Sanming Hu ◽  
Joshua Le-Wei Li
Keyword(s):  
High Speed ◽  
Dynamic Range ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Wide Dynamic Range
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