根据Real World Technologies公司技术分析师David Kanter日前发布的一份报告指出，苹果 iPad 3 设计存在重大瑕疪──其中所使用的图像处理器(GPU)效能不足，无法负荷 Retina 显示器的高阶需求。他明白指出，苹果在 iPad 3 上市才七个月后即迅速推出搭载三星32nm制程技术图像芯片的新一代 iPad 4，即显示苹果公司已发现且认定了这项设计疏失。
iPad 3采用Apple A5X双核处理器，X代表GPU四核心
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这份分析报告在此时出现，刚好就是媒体正大幅报导苹果准备将部份 A 系列处理器制造产线从三星转移到台积电(TSMC)之际。据报导，台积电将在本季开始试产用于 iPad 4 的 A6X 处理器。
iPad 4采用Apple A6X双核处理器。A5整合了两个SGX543 GPU核心，A5X整合了四个SGX543 GPU核心，A6X的图形性能两倍于A5X，苹果是如何做到的？我们推测，A6X不可能使用刚刚发布的新一代PowerVR核心，苹果可能仍然是提高频率，将GPU频率从A5X的 250MHz提高到500MHz
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从2011年三月起，业界许多传闻即指出苹果将把处理器制造产线从三星转移至台积电进行生产。苹果和三星双方长时间在全球针对专利侵权问题对簿公堂，包括去年在加州的一项法院判决。
就晶圆代工厂的角色来看，三星和台积电都能提供苹果最新的28nm制程，以支持苹果 A系列芯片所需的性能和更低功耗。但一位业界分析师猜测，苹果可能与三星之间存在长期代工服务合约，这便能解释为什么苹果逐步转移其于三星产能的做法。此 外，几乎在2012年大部分的时间里，台积电的28nm制程产能仍十分有限。
本文授权编译自EE Times，版权所有，谢绝转载
第二页：iPad 3上市七个月后下架的理由
第三页：iPad 3令苹果陷于流失用户的风险中
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• 传苹果联手台积电美国建芯片厂，加速去三星化
• iPad Mini缺货都是“去三星化”惹的祸
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Real World Technologies公司的Kanter说，对于苹果而言，利用最新的制程技术才是关键。 A5X 的高成本与功耗无疑地正是苹果为什么在 iPad 3 上市七个月后马上就决定下架 iPad 3 的理由之一。
苹果在今年三月发表 iPad 3 ，同时迅速采用了三星的‘Retina’显示器。然而， A5X 芯片中的图像处理器采用三星“传统的 SiON 闸极电介质45nm制程”，无法因应新款2,048×1,536显示器分辨率的更先进的要求，Kanter表示。
“为了因应这一趋势，AMD与Nvidia早在2012年1月即已推出台积电代工制造的高阶28nm GPU ，不过产能并不大，”Kanter说。
当三星32nm高K金属闸极制程出现后，苹果便能加速量产具有更高绘图性能的 A6X 芯片，从而推动 iPad 4 在9月上市。
“A6X 不仅提供较前一代芯片更好的绘图性能，同时也大幅缩小了芯片尺寸至123平方毫米，”Kanter说。
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本文授权编译自EE Times，版权所有，谢绝转载
第三页：iPad 3令苹果陷于流失用户的风险中
相关阅读：
• 传苹果联手台积电美国建芯片厂，加速去三星化
• iPad Mini缺货都是“去三星化”惹的祸
• 苹果iPad助阵，三星面板龙头地位岌岌可危pNVesmc
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Kanter 使用FLOPs/像素的比值来衡量苹果的平板电脑绘图效能，他指出， iPad 3 可实现198 FLOPS/像素的效能，远低于iPad 2的381 FLOPS/像素比。“就实际应用来看，这意味着任何能在 iPad 2 上顺利进行 3D 的应用，可能无法在 Retina 显示器上表现出来。”
iPad 3与iPad 2显示器效果对比
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Kanter认为，苹果公司为了保持领先的优势，抢先在 Google Nexus 10 等竞争对手的平板电脑产品上市前采用 Retina 显示器，最后却推出一款GPU效能不足且设计有瑕疪的 iPad 3 平板电脑，也自陷于流失部份用户的风险中。
本文授权编译自EE Times，版权所有，谢绝转载
编译：Susan Hong
参考英文原文：IPad 3 called 'unbalanced' as Apple, TSMC rumors fly，by Rick Merritt
相关阅读：
• 传苹果联手台积电美国建芯片厂，加速去三星化
• iPad Mini缺货都是“去三星化”惹的祸
• 苹果iPad助阵，三星面板龙头地位岌岌可危pNVesmc
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IPad 3 called 'unbalanced' as Apple, TSMC rumors fly
Rick Merritt
SAN JOSE, Calif. – The Apple iPad 3 is an unbalanced design with an underpowered graphics processor for its high-end display, according to an analysis released Wednesday (Jan. 2) by technology watcher David Kanter. Apple’s quick move to the iPad 4 with a graphics chip bolstered in part by Samsung’s new 32-nm process technology showed that Apple recognized the fault, he said.
The analysis emerges as reports circulate again that Apple is preparing to shift at least some of the manufacturing of its A series processors from Samsung to Taiwan Semiconductor Manufacturing Co. TSMC will start trial production this quarter of the A6X processor used in the iPad 4, according to several reports citing Taiwan newspapers.
Rumors have circulated since March 2011 that Apple will switch from Samsung to TSMC for foundry work. Apple and Samsung are locked in legal battles around the world over patent infringement including one resolved last year in a San Jose trial.
As foundries, Samsung and TSMC both could offer Apple the latest 28 nm processes to bolster performance and lower power for the A series chips. One analyst speculated that Apple may have a long term supply contract for foundry services at Samsung, explaining its slow shift away from its smartphone and tablet competitor. Through much of 2012, TSMC had limited availability of its 28-nm process.
Access to the latest process technology is key for Apple, said Kanter, principal of Real World Technologies. “The high cost and power consumption of the A5X was undoubtedly one of the reasons why Apple opted to discontinue the iPad 3 a mere seven months" after it was launched, he said.
Apple moved quickly to adopt the so-called Retina display from Samsung in the iPad 3 released in March. However, the graphics processor in the A5X chip Apple used--made in a 45-nm Samsung process using “conventional SiON gate dielectrics”--could not adequately feed the new 2048×1536 display, Kanter said.
Superior graphics
“To put this in perspective, AMD and Nvidia were already shipping high-end 28-nm GPUs fabbed by TSMC as early as January 2012, although not in particularly high volumes,” Kanter said.
When Samsung’s 32-nm high-K metal gate process became available, Apple was able to rev up production of the A6X chip with superior graphics to drive the iPad 4 launched in September.
“Not only did the A6X offer substantially better graphics performance than the previous generation, but the die size is also considerably smaller, at around 123 mm2,” Kanter wrote.
Kanter used a ratio of FLOPs/pixel to measure Apple’s tablet graphics performance, noting the iPad 3 delivered 198 FLOPs/pixel, far less than the 381 FLOPs/pixel of the iPad 2. “Practically speaking, this means that any 3D applications which were moderately taxing on the iPad 2 could not take advantage of the Retina display."
By adopting the Retina display before competing tablets such as the Google Nexus 10, Apple retained a leadership advantage at the risk of disappointing some users with an under-power GPU in an unbalanced system, Kanter said.
责编：Quentin
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