scholarly journals Open-Loop Class-BD Audio Amplifiers with Balanced Common-Mode Output

Electronics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1381
Author(s):  
Wojciech Kołodziejski ◽  
Stanisław Kuta ◽  
Jacek Jasielski
Keyword(s):  
Experimental Studies ◽  
Open Loop ◽  
Modulation Scheme ◽  
Output Stage ◽  
Radiation Emission ◽  
Common Mode ◽  
Audio Amplifiers ◽  
Gate Control ◽  
Output Filter ◽  
Gate Drivers

This paper presents new architectures and implementations of original open-loop Class-BD audio amplifiers with balanced Common-Mode output. The output stage of each proposed amplifier includes the typical H-bridge with four MOSFETs and four additional MOSFET switches that balance and keep the Common-Mode output constant. The presented amplifiers employ the extended NBDD PWM or PSC PWM modulation scheme. When the output stage is built only on NMOSFET transistors, gate drivers require a floating power supply, using a self-boost charge pump with capacitive isolation of the control signal. The use of complementary MOSFETs in the output stage greatly simplifies gate control systems. The proposed amplifiers were compared to the typical Class-BD configuration, using the optimal NBDD modulation with respect to audio performance of the Differential-Mode (DM) and Common-Mode (CM) outputs. Basic SPICE simulations and experimental studies have shown that the proposed Class-BD amplifiers have similar audio performance to the prototype with the optimal NBDD modulation scheme, while at the same time having a balanced constant voltage CM output, thus eliminating the main contributor to radiation emission. As a result, the filtering of the DM output signals can be greatly simplified, while the filtering of the CM output signals can be theoretically eliminated. Practically, due to the timing errors added by the gate drivers, spikes are generated at the CM output, which are very easy to filter out by the reduced LC output filter, even at very low L.

scholarly journals A 4-μW 0.8-V Rail-to-Rail Input/Output CMOS Fully Differential OpAmp

1970 ◽  
pp. 22
Author(s):  
M.R. Valero ◽  
S. Celma ◽  
N. Medrano
Keyword(s):  
Low Power ◽  
Low Voltage ◽  
Cmos Technology ◽  
Open Loop ◽  
Threshold Region ◽  
Input Output ◽  
Output Stage ◽  
Common Mode ◽  
Ultra Low Power ◽  
Rail To Rail

This paper presents an ultra low power rail-to-rail input/output operational amplifier (OpAmp) designed in a low cost 0.18 μm CMOS technology. In this OpAmp, rail-to-rail input operation is enabled by using complementary input pairs with gm control. To maximize the output swing a rail-to-rail output stage is employed. For low-voltage low-power operation, the operating transistors in the input and output stage are biased in the sub-threshold region. The simulated DC open loop gain is 51 dB, and the slew-rate is 0.04 V/μs with a 10 pF capacitive load connected to each of the amplifier outputs. For the same load, the simulated unity gain frequency is 131 kHz with a 64º phase margin. A common-mode feed-forward circuit (CMFF) increases CMRR, reducing drastically the variations in the output common mode voltage and keeping the DC gain almost constant. In fact, their relative error remains below 1.2 % for a (-20ºC, +120ºC) temperature span. In addition, the proposed OpAmp is very simple and consumes only 4 μW at 0.8 V supply.

Design of a New Low Power Fully Differential Amplifier with Settling Time Enhancement Characteristics

2015 ◽  
Vol 24 (06) ◽  
pp. 1550078 ◽  
Author(s):  
Seid Jafar Hosseinipouya ◽  
Farhad Dastadast
Keyword(s):  
High Performance ◽  
Settling Time ◽  
Cmos Process ◽  
Output Stage ◽  
Common Mode ◽  
Class Ab ◽  
Fully Differential ◽  
Op Amp ◽  
Transconductance Amplifier ◽  
Adaptive Biasing

High performance of fully differential operational transconductance amplifier is designed and implemented using a 0.18-μm CMOS process. The implemented op-amp uses common mode feedback (CMFB) circuit operating in weak inversion region which does not affect other electrical characteristics due to eliminating common mode (CM) levels automatically leading to improve CM rejection ratio (CMRR) of the amplifier significantly. Moreover, the output stage has class-AB operation so that its current can be made larger due to increasing the output current dynamically using adaptive biasing circuit. Additionally, the AC currents of the active loads have been significantly reduced using negative impedances to increase the gain of the amplifier. The results show the GBW 2.3 MHz, slew rate 2.6 V/μs and 1% settling time 150 ns with a capacitive load of 15 pF. This amplifier dissipates only 6.2 μW from a 1.2 V power supply.

A Space Vector Modulation Scheme of the Quasi-Z-Source Three-Level T-Type Inverter for Common-Mode Voltage Reduction

2018 ◽  
Vol 65 (10) ◽  
pp. 8340-8350 ◽  
Author(s):  
Changwei Qin ◽  
Chenghui Zhang ◽  
Alian Chen ◽  
Xiangyang Xing ◽  
Guangxian Zhang
Keyword(s):  
Modulation Scheme ◽  
Space Vector Modulation ◽  
Space Vector ◽  
Common Mode ◽  
Common Mode Voltage ◽  
Vector Modulation

Open-Loop Gate Control for Optimizing the Turn-ON Transition of SiC MOSFETs

2019 ◽  
Vol 7 (2) ◽  
pp. 1126-1136 ◽  
Author(s):  
Yang Han ◽  
Haifeng Lu ◽  
Yongdong Li ◽  
Jianyun Chai
Keyword(s):  
Open Loop ◽  
Turn On ◽  
Gate Control

scholarly journals Experimental studies of the air flow power action on the elements of protective mats

2019 ◽  
Vol 97 ◽  
pp. 05007
Author(s):  
Maria Umahseva ◽  
Yuliya Bryanskaya ◽  
Pavel Bazhin
Keyword(s):  
Power Flow ◽  
Aerodynamic Resistance ◽  
Experimental Studies ◽  
Resistance Coefficient ◽  
Open Loop ◽  
State University ◽  
Subsonic Wind Tunnel ◽  
Flow Power ◽  
The Impact ◽  
Positive Effect

The results of experimental studies to determine the coefficients of aerodynamic resistance in the flow of flexible protective concrete mats located on a horizontal plane are presented. The characteristics of the impact of the power flow on the system of flexible protective mats of various modifications in the aerodynamic laboratory of Moscow State University of Civil Engineering are specified. The experiment was carried out on a subsonic wind tunnel with an open loop using a rigid six-axis force and moment sensor. According to the results of the experiment, it was concluded that the resistance coefficient for the modification of mats with rounding of the upper part of the elements decreases. It has a positive effect on the performance characteristics of this model and increases the lifespan of a structure protected by this modification of coatings.

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