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 A 0.3 V, Rail-to-Rail, Ultralow-Power, Non-Tailed, Body-Driven, Sub-Threshold Amplifier

2021 ◽  
Vol 11 (6) ◽  
pp. 2528 ◽  
Author(s):  
Francesco Centurelli ◽  
Riccardo Della Sala ◽  
Giuseppe Scotti ◽  
Alessandro Trifiletti
Keyword(s):  
Supply Voltage ◽  
Cmos Technology ◽  
Gain Bandwidth ◽  
Common Mode ◽  
Input Stage ◽  
Fully Differential ◽  
Common Mode Voltage ◽  
Rail To Rail ◽  
The Common ◽  
Ultralow Power

A novel, inverter-based, fully differential, body-driven, rail-to-rail, input stage topology is proposed in this paper. The input stage exploits a replica bias control loop to set the common mode current and a common mode feed-forward strategy to set its output common mode voltage. This novel cell is used to build an ultralow voltage (ULV), ultralow-power (ULP), two-stage, unbuffered operational amplifier. A dual path compensation strategy is exploited to improve the frequency response of the circuit. The amplifier has been designed in a commercial 130 nm CMOS technology from STMicroelectronics and is able to operate with a nominal supply voltage of 0.3 V and a power consumption as low as 11.4 nW, while showing about 65 dB gain, a gain bandwidth product around 3.6 kHz with a 50 pF load capacitance and a common mode rejection ratio (CMRR) in excess of 60 dB. Transistor-level simulations show that the proposed circuit outperforms most of the state of the art amplifiers in terms of the main figures of merit. The results of extensive parametric and Monte Carlo simulations have demonstrated the robustness of the proposed circuit to PVT and mismatch variations.

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.

scholarly journals A New Approach to the PWM Modulation for the Multiphase Matrix Converters Supplying Loads with Open-End Winding

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 466
Author(s):  
Pawel Szczepankowski ◽  
Natalia Strzelecka ◽  
Enrique Romero-Cadaval
Keyword(s):  
Pulse Width Modulation ◽  
Harmonic Distortion ◽  
Simulation Software ◽  
Common Mode ◽  
New Approach ◽  
Matrix Converters ◽  
Load Voltage ◽  
Common Mode Voltage ◽  
The Common ◽  
Open End Winding

This article presents three variants of the Pulse Width Modulation (PWM) for the Double Square Multiphase type Conventional Matrix Converters (DSM-CMC) supplying loads with the open-end winding. The first variant of PWM offers the ability to obtain zero value of the common-mode voltage at the load’s terminals and applies only six switches within the modulation period. The second proposal archives for less Total Harmonic Distortion (THD) of the generated load voltage. The third variant of modulation concerns maximizing the voltage transfer ratio, minimizing the number of switching, and the common-mode voltage cancellation. The discussed modulations are based on the concept of sinusoidal voltage quadrature signals, which can be an effective alternative to the classic space-vector approach. In the proposed approach, the geometrical arrangement of basic vectors needed to synthesize output voltages is built from the less number of vectors, which is equal to the number of the matrix converter’s terminals. The PWM duty cycle computation is performed using only a second-order determinant of the voltages coordinate matrix without using trigonometric functions. A new approach to the PWM duty cycles computing and the load voltage synthesis by 5 × 5 and 12 × 12 topologies has been verified using the PSIM simulation software.

scholarly journals Opposite Triangle Carrier with SVPWM for Common-Mode Voltage Reduction in Dual Three Phase Motor Drives

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 282
Author(s):  
Seon-Ik Hwang ◽  
Jang-Mok Kim
Keyword(s):  
Electromagnetic Interference ◽  
Pulse Width Modulation ◽  
Motor Drives ◽  
Common Mode ◽  
Pwm Inverter ◽  
Common Mode Voltage ◽  
Voltage Vector ◽  
Three Phase ◽  
The Common ◽  
Zero Voltage

The common-mode voltage (CMV) generated by the switching operation of the pulse width modulation (PWM) inverter leads to bearing failure and electromagnetic interference (EMI) noises. To reduce the CMV, it is necessary to reduce the magnitude of dv/dt and change the frequency of the CMV. In this paper, the range of the CMV is reduced by using opposite triangle carrier for ABC and XYZ winding group, and the change in frequency in the CMV is reduced by equalizing the dwell time of the zero voltage vector on ABC and XYZ winding group of dual three phase motor.

scholarly journals Bandwidth and Common Mode Optimization for Current and Voltage Sources in Bioimpedance Spectroscopy

2021 ◽  
Vol 12 (1) ◽  
pp. 135-146
Author(s):  
Tobias Menden ◽  
Jascha Matuszczyk ◽  
Steffen Leonhardt ◽  
Marian Walter
Keyword(s):  
Patient Safety ◽  
Current Source ◽  
The Body ◽  
Voltage Source ◽  
Bioimpedance Spectroscopy ◽  
Laboratory Measurements ◽  
Output Impedance ◽  
Frequency Range ◽  
Common Mode ◽  
High Bandwidth

Abstract Bioimpedance measurements use current or voltage sources to inject an excitation signal into the body. These sources require a high bandwidth, typically from 1 kHz to 1 MHz. Besides a low common mode, current limitation is necessary for patient safety. In this paper, we compare a symmetric enhanced Howland current source (EHCS) and a symmetric voltage source (VS) based on a non-inverting amplifier between 1 kHz and 1 MHz. A common mode reduction circuit has been implemented in both sources. The bandwidth of each source was optimized in simulations and achieved a stable output impedance over the whole frequency range. In laboratory measurements, the output impedance of the EHCS had its -3 dB point at 400 kHz. In contrast, the VS reached the +3 dB point at 600 kHz. On average over the observed frequency range, the active common mode compensation achieved a common mode rejection of -57.7 dB and -71.8 dB for the EHCS and VS, respectively. Our modifications to classical EHCS and VS circuits achieved a low common mode signal between 1 kHz and 1 MHz without the addition of complex circuitry, like general impedance converters. As a conclusion we found VSs to be superior to EHCSs for bioimpedance spectroscopy due to the higher bandwidth performance. However, this only applies if the injected current of the VS can be measured.

scholarly journals Optimization of TSPWM for Common-Mode Voltage Reduction in Vehicular Electric Drive System

2021 ◽  
Vol 13 (1) ◽  
pp. 5
Author(s):  
Shang Jiang ◽  
Yuan Wang
Keyword(s):  
Electric Drive ◽  
Drive System ◽  
Modulation Method ◽  
Time Interval ◽  
Common Mode ◽  
Common Mode Voltage ◽  
Electric Drive System ◽  
The Common ◽  
Modulation Methods ◽  
Zero Voltage

Common-mode voltage can be reduced effectively by optimized modulation methods without increasing additional costs. However, the existing methods cannot satisfy the requirements of the vehicular electric-drive application. This paper optimizes the tri-state voltage modulation method to reduce the common-mode voltage for vehicular electric drive system applications. Firstly, the discontinuous switching issue during sector transition is analyzed. Under the limit of two switching times in one period, multiple alignments combination is proposed to address that issue. Secondly, the zero-voltage time intervals in different modulation ranges are explored. This paper proposes an unsymmetric translation method to reconstruct the voltage vector, and then the minimum zero-voltage time interval is controlled to enough value for safe switching. Finally, the proposed methods have been validated through experiments on a vehicular electric drive system. The results show that the common-mode voltage can be reduced effectively in the whole range with the optimized tri-state voltage modulation method.

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