Capacitative degradation of the common-mode rejection of differential amplifier circuits

1976 ◽  
Vol 14 (3) ◽  
pp. 350-355 ◽  
Author(s):  
R. L. G. Kirsner

The paper proposes a method based on new principle for removal of common mode voltages (CMVs) present in the differential signals # . These CMVs can be reduced nearly to zero without using any components with tight tolerances which is achieved using a new balancing technique. It is proved that the performance of the circuit depends only on the ratios and not on the individual values of the resistors because of which the performance of the circuit is not affected over the wide range of temperature. The circuit based on this principle was designed, constructed, tested and results are reported in this paper. Unlike the conventional techniques which use filters for removal of the common mode signals in specific band of the frequencies, the method reported here removes common mode signals of all known and unknown frequencies. Using this method, it is possible to extract very low values of the differential signals in the range of few microvolts where common mode voltages can be as high as few volts. It is possible to improve the effective common mode rejection ratio (CMRR) of any differential amplifier by a factor of more than 103 to 104 with this method.


Author(s):  
Hiroshi Hamada ◽  
Takuya Tsutsumi ◽  
Adam Pander ◽  
Hideaki Matsuzaki ◽  
Hiroki Sugiyama ◽  
...  

Frequenz ◽  
2020 ◽  
Vol 74 (7-8) ◽  
pp. 263-270
Author(s):  
Cao Zeng ◽  
Xue Han Hu ◽  
Feng Wei ◽  
Xiao Wei Shi

AbstractIn this paper, a tunable balanced-to-balanced in-phase filtering power divider (FPD) is designed, which can realize a two-way equal power division with high selectivity and isolation. A differential-mode (DM) passband with a steep filtering performance is realized by applying microstrip stub-loaded resonators (SLRs). Meanwhile, six varactors are loaded to the SLRs to achieve the center frequency (CF) and bandwidth adjustment, respectively. U-type microstrip lines integrated with stepped impedance slotline resonators are utilized as the differential feedlines, which suppress the common-mode (CM) intrinsically, making the DM responses independent of the CM ones. A tuning center frequency from 3.2 to 3.75 GHz and a fractional bandwidth (12.1–17.6%) with more than 10 dB return loss and less than 2.3 dB insertion loss can be achieved by changing the voltage across the varactors. A good agreement between the simulated and measured results is observed. To the best of authors' knowledge, the proposed balanced-to-balanced tunable FPD is first ever reported.


Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 466
Author(s):  
Pawel Szczepankowski ◽  
Natalia Strzelecka ◽  
Enrique Romero-Cadaval

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.


Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 282
Author(s):  
Seon-Ik Hwang ◽  
Jang-Mok Kim

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.


2007 ◽  
Author(s):  
Zdzislaw H. Klim ◽  
Marek Balazinski
Keyword(s):  

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