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 0.3 V Rail-to-Rail Ultra-Low-Power OTA with Improved Bandwidth and Slew Rate

2021 ◽  
Vol 11 (2) ◽  
pp. 19
Author(s):  
Francesco Centurelli ◽  
Riccardo Della Sala ◽  
Pietro Monsurrò ◽  
Giuseppe Scotti ◽  
Alessandro Trifiletti
Keyword(s):  
Low Power ◽  
Low Voltage ◽  
Supply Voltage ◽  
Cmos Process ◽  
Slew Rate ◽  
Large Signal ◽  
Output Stage ◽  
Ultra Low Power ◽  
Input Stage ◽  
Rail To Rail

In this paper, we present a novel operational transconductance amplifier (OTA) topology based on a dual-path body-driven input stage that exploits a body-driven current mirror-active load and targets ultra-low-power (ULP) and ultra-low-voltage (ULV) applications, such as IoT or biomedical devices. The proposed OTA exhibits only one high-impedance node, and can therefore be compensated at the output stage, thus not requiring Miller compensation. The input stage ensures rail-to-rail input common-mode range, whereas the gate-driven output stage ensures both a high open-loop gain and an enhanced slew rate. The proposed amplifier was designed in an STMicroelectronics 130 nm CMOS process with a nominal supply voltage of only 0.3 V, and it achieved very good values for both the small-signal and large-signal Figures of Merit. Extensive PVT (process, supply voltage, and temperature) and mismatch simulations are reported to prove the robustness of the proposed amplifier.

Design of the variable frequency oscillator in DC-DC converter

Circuit World ◽  
2019 ◽  
Vol 45 (2) ◽  
pp. 80-85
Author(s):  
Tian Lei ◽  
Nan Gong ◽  
Li Wang ◽  
Qin Qin Li ◽  
Heng Wei Wang
Keyword(s):  
Supply Voltage ◽  
Operating Frequency ◽  
Maximum Deviation ◽  
Variable Frequency ◽  
Cmos Process ◽  
Power Supply Voltage ◽  
Output Stage ◽  
Content Type ◽  
Oscillator Frequency ◽  
Light Load

Purpose Because of the logic delay in the converter, the minimum turn on time of the switch is influenced by the constant time. When the inductor current gets to the threshold of the chip, the control signal will delay for a period. This makes the inductor current rising with the increasing of the clock and leads to the load current out of control. Thus, this paper aims to design an oscillator with a variable frequency protection function. Design/methodology/approach This paper presents an oscillator with the reducing frequency applied in the DC-DC converter. When the converter works normally, the operating frequency of the oscillator is 1.5 MHz. So the inductor current has enough time to decay and prevent the power transistor damaging. After the abnormal condition, the converter returns to the normal operating mode automatically. Findings Based on 0.5 µm CMOS process, simulated by the HSPICE, the simulation results shows that the frequency of the oscillator linearly decreases from 1.5 MHz to 380 KHz when the feedback voltage less than 0.2 V. The maximum deviation of the oscillator frequency is only 6 per cent from −50°C to 125°C within the power supply voltage of 2.7-5.5 V. Originality/value When the light load occurs at the output stage, the oscillator frequency will decrease as the load voltage drops. The test results shows that when the circuit works in the normal condition, the oscillator frequency is 1.5 MHz. When the load decreased, the operating frequency is dropped dramatically.

1.2 V CMOS output stage with improved drive capability

1999 ◽  
Vol 35 (5) ◽  
pp. 358 ◽  
Author(s):  
G. Palumbo
Keyword(s):  
Output Stage

AN IMPROVED DIFFERENTIAL COMPARATOR WITH FIELD EFFECT DIODE OUTPUT STAGE

2005 ◽  
Vol 14 (05) ◽  
pp. 931-937 ◽  
Author(s):  
IRAJ SHEIKHIAN ◽  
FARSHID RAISSI
Keyword(s):  
Field Effect ◽  
Output Stage ◽  
Chip Area ◽  
The Third ◽  
Large Current ◽  
The Third Terminal ◽  
On Line ◽  
Soi Technology

In a field effect diode, carriers of a p–n junction can be modulated on-line. The p and n regions are created by two oppositely biased, and closely spaced, gates in CMOS SOI technology. Using gates as the third terminal, the field effect diode can operate as a switch or as an amplifying element. In this paper, a conventional differential comparator is designed and its performance is compared with a circuit which uses field effect diodes in its output stage. It is shown that the large current sinking and supplying capability of the field effect diode causes this comparator to operate faster than the conventional circuit, consumes less power and covers less chip area.

HIGH-SLEW RATE LOW-QUIESCENT CURRENT RAIL-TO-RAIL CMOS BUFFER AMPLIFIER FOR FLAT PANEL DISPLAYS

2011 ◽  
Vol 20 (07) ◽  
pp. 1277-1286 ◽  
Author(s):  
MERIH YILDIZ ◽  
SHAHRAM MINAEI ◽  
EMRE ARSLAN
Keyword(s):  
Power Supply ◽  
Monte Carlo Analysis ◽  
Cmos Process ◽  
Flat Panel Displays ◽  
Slew Rate ◽  
Flat Panel ◽  
Output Stage ◽  
Rail To Rail ◽  
Buffer Amplifier ◽  
Quiescent Current

This work presents a high-slew rate rail-to-rail buffer amplifier, which can be used for flat panel displays. The proposed buffer amplifier is composed of two transconductance amplifiers, two current comparators and a push-pull output stage. Phase compensation technique is also used to improve the phase margin value of the proposed buffer amplifier for different load capacitances. Post-layout simulations of the proposed buffer amplifier are performed using 0.35 μm AMS CMOS process parameters and 3.3 V power supply. The circuit is tested under a 600 pF capacitive load. An average settling time of 0.85 μs under a full voltage swing is obtained, while only 3 μA quiescent current is drawn from the power supply. Monte Carlo analysis is also added to show the process variation effects on the circuit.

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