scholarly journals A Low-Power Stable Wideband Current Source for Acupuncture Point Skin Impedance Measurements

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Changpei Qiu ◽  
Tianxia Zhao ◽  
Qiuping Li ◽  
Xin’an Wang ◽  
Kanglin Xiao ◽  
...  
Keyword(s):  
Low Power ◽  
Current Source ◽  
Harmonic Distortion ◽  
Acupuncture Point ◽  
Cmos Technology ◽  
Skin Impedance ◽  
Output Impedance ◽  
Output Current ◽  
Impedance Measurements ◽  
The Stability

A low-power stable wideband current source for acupuncture point skin impedance measurements has been designed employing a differential architecture and negative feedback. The circuits extend bandwidth to 1 MHz, reducing harmonic distortion to 0.24% at 1 MHz. The output impedance is 37 MΩ at 100 kHz and 11 MΩ at 1 MHz. The stability of the output current of the current source when connected to different loads is below 0.1% at frequencies up to 500 kHz and increases to 0.74% at 1 MHz. The circuit was manufactured in a 0.13-μm CMOS technology and measured results are presented. The area of the current source is 0.09 mm2 and its consumption is 1.2 mW. It is intended for low-power acupuncture point skin impedance measurements.

scholarly journals Low power current sources for bioimpedance measurements: a comparison between Howland and OTA-based CMOS circuits

2019 ◽  
Vol 3 (1) ◽  
pp. 66-73 ◽  
Author(s):  
Pedro Bertemes-Filho ◽  
Volney C. Vincence ◽  
Marcio M. Santos ◽  
Ilson X. Zanatta
Keyword(s):  
Low Power ◽  
Current Source ◽  
Harmonic Distortion ◽  
Input Voltage ◽  
Wide Frequency Range ◽  
Current Conveyor ◽  
Invasive Technique ◽  
Output Impedance ◽  
Current Frequency ◽  
Class Ab

Abstract Multifrequency Electrical Bioimpedance (MEB) has been widely used as a non-invasive technique for characterizing tissues. Most MEB systems use wideband current sources for injecting current and instrumentation amplifiers for measuring the resultant potential difference. To be viable current sources should have intrinsically high output impedance for a very wide frequency range. Most contemporary current sources in MEB systems are based on the Howland circuit. The objective of this work is to compare the Mirrored Modified Howland Current Source (MMHCS) with three Operational Transconductance Amplifier (OTA) based voltage controlled current sources (i.e., class-A, class-AB and current conveyor). The results show that both current conveyor and class-AB OTA-based current sources have a wider output current frequency response and an output impedance of 226% larger than the MMHCS circuit at 1 MHz. The presented class-AB OTA circuit has a power consumption of 4.6 mW whereas current conveyor consumed 1.6 mW. However, the MMHCS circuit had a maximum total harmonic distortion of 0.5% over the input voltage from -0.5 to +0.5 V. The OTA-based current sources are going to be integrated in a semiconductor process. The results might be useful for cell impedance measurements and for very low power bioimpedance applications.

scholarly journals Design of an Ultra-Low Voltage Bias Current Generator Highly Immune to Electromagnetic Interference

2021 ◽  
Vol 11 (1) ◽  
pp. 6
Author(s):  
Orazio Aiello
Keyword(s):  
Integrated Circuits ◽  
Electromagnetic Interference ◽  
Low Voltage ◽  
Current Source ◽  
Building Blocks ◽  
Cmos Technology ◽  
Threshold Region ◽  
Output Current ◽  
Current Generator ◽  
Technology Process

The paper deals with the immunity to Electromagnetic Interference (EMI) of the current source for Ultra-Low-Voltage Integrated Circuits (ICs). Based on the properties of IC building blocks, such as the current-splitter and current correlator, a novel current generator is conceived. The proposed solution is suitable to provide currents to ICs operating in the sub-threshold region even in the presence of an electromagnetic polluted environment. The immunity to EMI of the proposed solution is compared with that of a conventional current mirror and evaluated by analytic means and with reference to the 180 nm CMOS technology process. The analysis highlights how the proposed solution generates currents down to nano-ampere intrinsically robust to the Radio Frequency (RF) interference affecting the input of the current generator, differently to what happens to the output current of a conventional mirror under the same conditions.

MIXED MODE UNIVERSAL FILTER

2013 ◽  
Vol 22 (01) ◽  
pp. 1250064 ◽  
Author(s):  
NEETA PANDEY ◽  
SAJAL K. PAUL
Keyword(s):  
Mixed Mode ◽  
Cmos Technology ◽  
Output Impedance ◽  
Universal Filter ◽  
Output Current ◽  
Voltage Signal ◽  
Low Pass ◽  
Band Pass ◽  
Electronically Tunable ◽  
High Pass

The configuration with electronic tunable characteristics that can work in mixed mode may be useful from IC realization viewpoint and application adaptability. This paper proposes an electronically tunable mixed mode universal filter based on multiple output current controlled current conveyor (MOCCCII) and this single topology without any alteration can be used in all four modes i.e., voltage (VM), current (CM), transimpedance (TIM) and transadmittance (TAM). The architecture uses four MOCCCIIs and two grounded capacitors; and can realize universal filter functions — low pass (LP), band pass (BP), high pass (HP), notch (NF) and all pass (AP) for all four modes. Moreover the input impedance is high and output impedance is low for voltage signal and vice-versa for current signal, hence the proposed topology is suitable for cascading for all four modes. The workability of the proposed circuit has been verified via SPICE simulations using AMS 0.35 μm CMOS technology.

Design and implementation of low-power CMOS biosignal amplifier for active electrode in biomedical application using subthreshold biasing strategy

2019 ◽  
Vol 18 (01) ◽  
pp. 1941017
Author(s):  
G. Kalpana ◽  
Raja Krishnamoorthy ◽  
P. T. Kalaivaani
Keyword(s):  
Low Power ◽  
Integrated Circuit ◽  
Digital Signal Processor ◽  
Biomedical Application ◽  
Research Work ◽  
Cmos Technology ◽  
Motion Artifacts ◽  
Skin Impedance ◽  
Cochlear Prosthesis ◽  
Active Electrode

Active Electrodes (AEs) are electrodes which have integrated bio-amplifier circuitry and are known to be less susceptible to motion artifacts and environmental interference. In this work, a low-power and high-input impedance amplifier for active electrode application is implemented based on subthreshold biasing strategies. In this proposed Application Specific Integrated Circuit (ASIC) device was versatile and numerical to achieve a high degree of programmability. It could be adapted to any other external part of one cochlear prosthesis, the sound analyzer that could be driven by a Digital Signal Processor (DSP). This research work also discusses the measurement of the electrode-skin impedance mismatch between two electrodes while concurrently measuring a bioelectrical signal without degradation of the performance of the amplifier, the efficient, noise-optimized analysis of bioelectrical signals utilizing two-wired active buffer electrodes. The reduction of power-line interference when using amplifying electrodes employing autonomous adaption of the gain of the subsequent differential amplification. The amplifier’s features include offset compensation, Common Mode Rejection Ratio (CMRR) improvement in software and a bandwidth extending down to DC. The proposed active electrode amplifier is designed using 90 nm CMOS technology. Simulation results exhibit up to the change in noise immunity and lessening in power utilization contrasted with the traditional bio-amplifier design at a similar delay.

Design and Simulation of Low-Power Multistage Amplifiers

2011 ◽  
Vol 378-379 ◽  
pp. 655-658
Author(s):  
Ming Yuan Ren
Keyword(s):  
Low Power ◽  
Cmos Technology ◽  
Frequency Compensation ◽  
Transient Responses ◽  
Gain Bandwidth ◽  
Silicon Area ◽  
Multistage Amplifiers ◽  
Capacitive Load ◽  
The Stability ◽  
Multistage Amplifier

This paper presents a low-power multistage amplifier with a novel capacitor-multiplier frequency compensation (CMFC) technique. The proposed compensation strategy can allow the circuit to occupy less silicon area and to drive large capacitive loads more effectively. Moreover, smaller physical capacitance results in higher gain-bandwidth product (GBW) and improved transient responses. Furthermore, the capacitor multiplier stage (CMS) embedded in CMFC creates a left-half plane (LHP) zero, which boosts the phase margin and enhances the stability of the amplifier. Implemented in a commercial 0.5-μm CMOS technology and driving 500pF capacitive load, a three-stage CMFC amplifier achieves over 120dB gain, 1.699MHz GBW and 1.625V/μS average slew rate, while only dissipating 330μW under 3.3V supply.

scholarly journals Design of current sources for load common mode optimization

2018 ◽  
Vol 9 (1) ◽  
pp. 59-71
Author(s):  
Vinicius G Sirtoli ◽  
Kaue F Morcelles ◽  
Volney C Vincence
Keyword(s):  
Voltage Drop ◽  
Current Source ◽  
Output Impedance ◽  
Output Current ◽  
Common Mode ◽  
Measurement Systems ◽  
Fully Differential ◽  
Common Mode Voltage ◽  
The Common ◽  
Bioimpedance Measurement

Abstract Bioimpedance measurement systems often use the Howland current sources to excite the biological material under study. Usually, difference or instrumentation amplifiers are used to measure the resulting voltage drop on this material. In these circuits, common mode voltage appears as artifacts in the measurement. Most researches on current sources are focused on improving the output impedance, letting other characteristics aside. In this paper, it is made a brief review on the load common mode voltage and output swing of various topologies of Howland current sources. Three circuits are proposed to reduce load common mode voltage and enhance load capability by using a fully differential amplifier as active component. These circuits are equated, simulated and implemented. The three proposed circuits were able to deliver an output current with cut-off frequency (-3dB) higher than 1 MHz for loads as big as 4.7 kΩ. The worst measured load common mode voltage was smaller than 24 mV for one of the circuits and smaller than 8 mV for the other two. Consequently, it could be obtained increases in the Common Mode Rejection Ratio (CMRR) up to 60 dB when compared to the Enhanced Howland Current Source (EHCS).

scholarly journals Optically isolated current source

2019 ◽  
Vol 6 (1) ◽  
pp. 18-21
Author(s):  
F. J. Pettersen ◽  
J. O. Høgetveit
Keyword(s):  
Current Source ◽  
Operational Amplifiers ◽  
Output Impedance ◽  
Output Current ◽  
Passive Components ◽  
Medical Settings ◽  
Spice Model ◽  
High Linearity ◽  
Small Load ◽  
Bioimpedance Measurement

Abstract There is a need for isolated current sources for use in selected bioimpedance measurement circuits. The requirement for good isolation is particularly important in medical settings because of safety concerns. A new circuit for producing voltage-controlled current is presented. Measurements have been made on a prototype and simulations have been done on a SPICE model. The presented circuit is an H-bridge where the output devices are the output photodiodes of high-linearity optocouplers. Five operational amplifiers, four high linearity optocouplers, and passive components are used. Output current capability is ±35 μA with an output impedance that is more than 1 M Ω. It is possible to achieve bandwidths above 1 MHz for small load impedances. This circuit is well suited for medical applications thanks to the isolation in the optocouplers.

An Efficient Architecture for Accurate and Low Power CMOS Analog Multiplier

2020 ◽  
pp. 2150045
Author(s):  
Tohid aghaei ◽  
Ali Naderi Saatlo
Keyword(s):  
Low Power ◽  
Power Dissipation ◽  
Harmonic Distortion ◽  
Cmos Technology ◽  
The Body ◽  
Body Effect ◽  
Low Power Dissipation ◽  
Low Power Cmos ◽  
Amplitude Modulator ◽  
Four Quadrant

A new analog four-quadrant multiplier in CMOS technology is proposed using translinear loops (TLs). The novelty of the work includes an improved structure resulting in high precision output, low power consumption and low body effect error. The higher accuracy is achieved using a symmetrical arrangement of the proposed multiplier, where the errors on the two sides of circuit are subtracted from each other. The simple structure, as well as the sharing bias branch in the squaring circuits, leads to the low power dissipation of the multiplier circuit. In addition, the proposed circuit is thoroughly analyzed in terms of the body effect error and the results are presented. In order to validate the performance of the circuit, the designed multiplier is used in two useful applications: frequency doubler and amplitude modulator. The post layout simulation results of the circuit are performed using Cadence Virtuoso and HSPICE with level 49 parameters (BSIM3v3) of TSMC 0.18[Formula: see text][Formula: see text]m technology. The results show a nonlinearity of 0.93%, a total harmonic distortion (THD) of 0.98% at a frequency of 1[Formula: see text]MHz, a [Formula: see text]3[Formula: see text]dB bandwidth of 736[Formula: see text]MHz and a maximum power dissipation of 0.0619[Formula: see text]mW.

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