恒定输出的D类音频放大器

美国国家半导体公司推出内置升压转换器的Boomer音频放大器LM48510。无需加设外置升压转换器。即使电池渐渐耗尽以致电压下降，输出功率也可稳定保持在原先较高的水平。     

新型D类放大器优化数字电视音频表现

数字电视与便携式音频产品是驱动目前音频市场的两大动力。数字电视的特点是,它需要一个简单的影院系统,同时又能实现出色的音频效果。针对数字电视的这一特点,CirrusLogic公司最近推出一个面向数字电视和家庭影院的D类数字放大器解决方案——CS44130功率级IC。 CS44130集成了4个D类放大器,由于采用 N P沟道结构,它的抗EMI性能优于N N沟道架构的同类产品。Cirrus Logic的专利技术Pop-     

无滤波器D类音频放大器

无滤波器的D类音频放大器NCP2820能通过5V电源为一个4Q桥式连接负载（BTL）提供2．65W的连续平均功率，或为8Q桥式连接负载提供1．4W功率，而总谐波失真加噪声（THD＋N）小过1％。输入电压为2．5～5．5V，效率为90％，关断电流为0．42μA。可消除启动或关断时的噪声，使用A加权滤波器能确保获得净化的音频输出。     

高效D类立体声音频放大器TPA005D02

ＴＰＡ００５Ｄ０２是一种用于音频系统的高效、高保真度Ｄ类放大器。本文介绍了它的工作原理、性能特点以及与它相匹配的输出滤波器设计。     

高效率D类音频放大器MAX9700/9712

MAX9700/9712是MAXIM公司的两款低EMI、免滤波、高效率单声道D类音频放大器, MAX9712能够以高于85%的效率为8Ω负载提供0.5W的功率,MAX9700转换效率更是达到90%以上,可为8Ω负载提供1.2W的功率。采用MAXIM专有的低EMI调制方案省去了输出滤波器和散热器,从而节省电路板空间,延长     

低EMI、D类音频放大器及其应用

本文介绍了新型D类音频放大器(MAX9700/MAX9712)的功能、特点,及其应用方案。     

集成化D类音频放大器

集成化D类音频放大器是一类较为新型的半导体集成电路，本文就其工作原理，结构特性和应用领域等方面，作了一些简要的讨论与介绍。     

用D类放大器提高音频放大效率

D类采用脉宽调制(PWM)信号取代AB类放大器通常采用的线性信号。PWM信号包括音频信号以及PWM开关频率与谐波。D类音频放大器比AB类放大器效率高得多,因为输出MOSFET可从极高阻抗转变为极低阻抗,从而在作用区操作只有几纳秒。利用上述技术,输出级上损失的功率极低。此     

集成化D类音频放大器

集成化D类音频放大器是一类较为新型的半导体集成电路，本文就其工作原理、结构特性和应用领域等方面，作了一些简要的讨论与介绍。     

带集成输出级的无滤波器D类立体声音频放大器SSM2302

Analog Devices’公司生产的SSM2302单片机IC是一种集成了输出级的无滤波器高性能D类立体声音频放大器。SSM2302利用2．5-5．0V的单电源工作，适用于移动电话、MP3播放机、手持游戏机和教育玩具等电池供电的消费类电子产品。     

D类放大器的散热考虑

与AB类放大器相比,D类放大器有更好的效率和热性能,但实现一个D类放大器仍然需要注意良好的电气设计与热设计方法。大多数工程师使用一种连续的正弦波输入信号,在实验室中评估D类放大器的性能。尽管正弦波用于测量时很方便,但对放大器热负荷却是一种最糟的情况。如果你用近乎最大输出功率的连续正弦波驱动一个D类放大器,则放大器会经常进入热关断状态。     

D类音频功率放大器的评估及应用

现今几类基本功放拓扑中,AB类功率放大器已经被广泛的应用于各种音频产品,包括手机、mp3播放器和PMP系统中。考虑到AB类功率放大器能够提供高品质的信号放大性能,因此非常适合耳机和一些小功率喇叭的应用。但是由于更多、更新的便携式产品对     

便携式音频功率放大器综述

便携式电子产品的发展推动了各种元器件的不断改进。本文以便携式音频功率放大器这一类器件的发展概况作一些介绍。     

A power supply error correction method for single-ended digital audio class D amplifiers

In single-ended digital audio class D amplifiers (CDAs), the errors caused by power supply noise in the power stages degrade the output performance seriously. In this article, a novel power supply error correction method is proposed. This method introduces the power supply noise of the power stage into the digital signal processing block and builds a power supply error corrector between the interpolation filter and the uniform-sampling pulse width modulation (UPWM) lineariser to pre-correct the power supply error in the single-ended digital audio CDA. The theoretical analysis and implementation of the method are also presented. To verify the effectiveness of the method, a two-channel single-ended digital audio CDA with different power supply error correction methods is designed, simulated, implemented and tested. The simulation and test results obtained show that the method can greatly reduce the error caused by the power supply noise with low hardware cost, and that the CDA with the proposed method can achieve a total harmonic distortion + noise (THD + N) of 0.058% for a –3 dBFS, 1 kHz input when a 55 V linear unregulated direct current (DC) power supply (with the –51 dBFS, 100 Hz power supply noise) is used in the power stages.     

3-state BTL closed-loop PWM Class D amplifiers

One of the shortcomings of a number of Class D amplifiers (CDAs) designs is their susceptibility to supply noise, quantified by Power Supply Rejection Ratio (PSRR). Reported investigations thereto to-date remain incomplete/over-simplified, particularly the assumption that the AC ground is noise-less and a simplified fully-differential integrator model. In this paper, the effect of supply noise in the AC ground to PSRR is analytically investigated, and the associated analytical expressions derived. Of specific interest, the analysis is applied to the ubiquitous 3-state Bridge-tied-load (BTL) closed-loop PWM CDA, taking into consideration not only the effect of the non-ideal AC ground, but also the effect of the resistor and capacitor mismatch based on a realistic fully-differential integrator model. Further, the PSRR analysis of 3-state BTL closed-loop CDAs has to date been limited to the single-feedback topology and in this paper, extended to the double-feedback topology. These analyses and derived equations herein are useful as they provide valuable insights to CDA designers into the PSRR mechanisms—for example, the counter-intuitive observation that the CDA with 1st-order integrators provides similar or better PSRR than the CDA with 2nd-order integrators if both CDAs are designed to the same carrier attenuation—including the effect of various circuit parameters, and ensuing trade-offs. The derived analytical expressions are verified by means of HSPICE simulations and on the basis of practical measurements on discretely-realized CDAs.     

A design methodology for high-order class-D audio amplifiers

This paper presents a design methodology for high-order class-D amplifiers, based on their similarity with sigma–delta ( $\Upsigma\Updelta$ ) modulators, for which established theory and toolboxes are available. The proposed methodology, which covers the entire design flow, from specifications to component sizing, is validated with three design examples, namely a second-order, a third-order, and a fourth-order class-D amplifier. Moreover, the third-order class-D amplifier has been integrated on silicon and characterized, further confirming the validity of the whole design flow. The achieved results demonstrate that high-order class-D amplifiers can achieve total-harmonic-distortion (THD) performance compatible with the specifications of high-end audio applications (THD  ≈ 90 dB), which would be unfeasible with conventional first-order class-D amplifiers.     

Class D audio power amplifier with fine hysteresis control

A new simple and efficient control method for a class D audio power amplifier is presented. The new fine hysteresis control method can control the switching frequency freely and guarantees stability for any load condition without having any outside compensation circuit at all.     

Integrated overcurrent protection system for class-D audio power amplifiers

A fully integrated overcurrent protection system is presented suitable for application in integrated class-D audio power amplifiers. Accurate overcurrent detection is used based on parallel measurement of the voltage drop across the DMOS power transistors. A logic circuit enables continuous current limiting during overload situations. Actual short circuits can be distinguished from load impedance minima using a simple short-circuit discrimination method.     

Switched-capacitor filters using unity-gain amplifiers

Switched-capacitor networks realizing second-order filter characteristics are presented. Realization is achieved with unity-gain amplifiers as buffers. The circuits have small sensitivities, good dynamic range and a reasonable spread of capacitor values. The filters can be used for high-Q realization and a relatively high frequency range.     

RC-active filters using unity-gain amplifiers

A new active-filter configuration consisting of RC elements and a single unity-gain amplifier is suggested. The method may realise many useful 2nd-order transfer functions with a small number of RC elements.