Inside the A4 processor
Having established the A4 characteristics are consistent with some of the rumored innovations, our next step was to begin analysis at the silicon and firmware level to determine what, if any, patented improvements are implemented in the chip. We used various means to study the chip itself including a functional layout analysis which reveals the processor silicon down to silicon substrate level and exposes the various building blocks of the processor. We also ran some proprietary benchmarking tests.
Our functional layout analysis identified various memory blocks and logic areas. Identification of processor core, however, takes more than locating memory blocks and logic areas. Through various benchmarking testing, UBM TechInsights was able to find out the details of the A4 processor in the table below.
According to information provided by ARM, a Cortex-A8 core implemented with 65nm process technology is capable of achieving 1GHz operation. Given that the A4 is a 45nm process part, the processor appears to have been optimized to strike a balance between performance and power consumption. Also it was confirmed that the A4 processor has support for ARM's Neon media instruction set extensions.
With further analysis, including chip-level reverse engineering, we may be able to identify whether innovations such as Intrinsity’s patented cell libraries were used to optimize the critical paths in the ARM core itself.
Our findings thus far confirm a predictable march forward in processing power through advancing core technology, reduced process geometries, and a careful architectural balance between speed and power consumption. Our findings also point out the somewhat muted impact that further CPU power reduction would bring to the table.
Until display technologies make big moves downward in power consumption the consumer experience of battery life may be driven as much or more by the LED drivers, opto-mechanical design of the back-lighting, display settings and wireless connectivity employed versus the CPU itself.
Young Choi is a Senior Manager at UBM TechInsights responsible for business planning, device segment roadmaps, analysis and technical marketing.