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万里无云千丈见底
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作者 周彦武 《视听技术》 1997年第1期78-79,共2页
一、书架箱的哲学 现代书架箱有一种值得商榷的设计倾向,一方面采用那些振膜或折环具有较高阻尼的单元,另一方面提高线圈电感的品质因数Q值,一般提升至0.8~1.0,目的是希望挤出更多的低频。再有的就是提高书架箱的灵敏度,希望有更大的... 一、书架箱的哲学 现代书架箱有一种值得商榷的设计倾向,一方面采用那些振膜或折环具有较高阻尼的单元,另一方面提高线圈电感的品质因数Q值,一般提升至0.8~1.0,目的是希望挤出更多的低频。再有的就是提高书架箱的灵敏度,希望有更大的低频声压输出能力,还有的采用正面开倒相孔的箱体,目的是为了有更好的低频响应。 展开更多
关键词 金嗓子 清晰度 小功率放大器 品质因数 无云 频率响应 书架 高阻尼 设计倾向 后反射
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话说书架箱
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作者 叶新海 《视听技术》 1997年第8期52-53,共2页
什么是书架箱? 说起书架箱,人们自然而然会联想到与它相对应的落地箱。落地箱指体积较大,尤其是有一定高度的音箱,一般直接摆放在地上使用。那么以此类推,书架箱是不是摆在书架上使用的音箱呢?其实书架箱并非指放在书架上使用,而是那些... 什么是书架箱? 说起书架箱,人们自然而然会联想到与它相对应的落地箱。落地箱指体积较大,尤其是有一定高度的音箱,一般直接摆放在地上使用。那么以此类推,书架箱是不是摆在书架上使用的音箱呢?其实书架箱并非指放在书架上使用,而是那些体积较小尤其是高度相对较小、摆放灵活的小音箱的统称。“书架箱”是音响界一个主要的误称,这一名称来源于英文“NookshelfLoudspeaker”,直译成中文就是“ 展开更多
关键词 书架 失真度 低音喇叭 低频响应 灵敏度指标 极低频 小口径 小功率放大器 箱体容积 最大输出
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Wavelet network based predistortion method for wideband RF power amplifiers exhibiting memory effects 被引量:1
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作者 JIN Zhe SONG Zhi-huan HE Jia-ming 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第4期625-630,共6页
RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryl... RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryless predistortion cannot linearize PAs effectively. After analyzing PA memory effects, a novel predistortion method based on wavelet networks (WNs) is proposed to linearize wideband RF power amplifiers. A complex wavelet network with tapped delay lines is applied to construct the predistorter and then a complex backpropagation algorithm is developed to train the predistorter parameters. The simulation results show that compared with the previously published feed-forward neural network predistortion method, the proposed method provides faster convergence rate and better performance in reducing out-of-band spectral regrowth. 展开更多
关键词 Power amplifiers. Predistortion. Memory effects. Wavelet networks
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Robust MSE precoder for imperfectly known MIMO wireless correlated channel 被引量:1
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作者 马鹏飞 赵慧 王文博 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第1期36-40,共5页
Aimed at that only one form of channel statistic information is utilized in traditional robust precoder schemes: either the channel mean or the transmit antenna correlation in multiple-input multiple-output (MIMO) wir... Aimed at that only one form of channel statistic information is utilized in traditional robust precoder schemes: either the channel mean or the transmit antenna correlation in multiple-input multiple-output (MIMO) wireless system, this paper proposes robust precoder designs which exploit both of statistic information to minimize the equalization mean-square error (MSE) with power constraint. Two different power constraints are studied. Besides the usual sum power constraint over all antennas, the per-antenna power constraint is imposed at transmitter in this paper. Since each antenna has its own amplifier, individual power constraint on each antenna is more realistic. Especially in MIMO-OFDM systems, the Peak-to-Average Ratio (PAR) is one of main practical problems. Simulations show that the proposed schemes have better performance than traditional normalized zero forcing schemes for imperfectly known correlated channel. Moreover, per-antenna power constraint can efficiently decrease the demand of dynamic range of power amplifier on each transmit antenna, especially in MIMO-OFDM systems. 展开更多
关键词 preeoder convex optimization imperfect channel knowledge multiple-input multiple-output MIMO) systems
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UHF power amplifier design in 0.35μm SiGe BiCMOS
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作者 宋家友 Li Zhiqun Wang Zhigong 《High Technology Letters》 EI CAS 2009年第2期147-150,共4页
A two-stage power amplifier operated at 925 MHz was designed and fabricated in Jazz' s 0.35μmSiGe BiCMOS process.It was fully integrated excluding the inductors and the output matching network.Under a single 3.3V... A two-stage power amplifier operated at 925 MHz was designed and fabricated in Jazz' s 0.35μmSiGe BiCMOS process.It was fully integrated excluding the inductors and the output matching network.Under a single 3.3V supply voltage,the off-chip bonding test results indicated that the circuit has a smallsignal gain of more than 24dB,the input and output reflectance are less than- 24dB and-10dB,re-spectively,and the maximal output power is 23.5 dBm.At output power of 23.1 dBm,the PAE(poweradded efficiency)is 30.2%,the IMD2 and IMD3 are less than- 32 dBc and-46 dBc,respectively.The chip size is 1.27mm ×0.9mm. 展开更多
关键词 power amplifier SIGE BICMOS heterojuncfion bipolar transistor
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15W后级功放
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作者 双成 《音响技术》 1995年第5期1-1,共1页
关键词 中点电位 小功率放大器 集成电路 扬声器保护 零点漂移 动态范围 晶体管参数 失真因素 差分放大 输入阻抗
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