Apple iPhone 4
We have confirmed that the iPhone's A4 processor has 512 MB RAM, unlike the iPad's more limited 256 MB. This decision may have been made fairly late in Apple's development cycle, because early leaked prototype phones only had 256 MB.
The all-new iPhone 4 features upgrades from the 3GS including:
• A redesigned glass & stainless steel body that shaves 3.5 mm off the width and is 3 mm thinner than the 3GS.
• Choice of black or white coloring
• Retina display featuring four times the pixel density of the 3GS
• iOS 4 for multi-tasking
• 5 MP, 720p capturing rear-facing and VGA front-facing cameras 
An iPhone first: Interestingly enough, the storage capacity is not etched on the outer case of the iPhone 4. We'd expect our 32 GB iPhone 4 to fulfill its promise and give us, well, 32 GB. Unfortunately it has an actual capacity of 29.06 GB. Given the fact that 301 MB of "other" data is being stored in memory, this leaves the user with 28.77 GB of free space.
In terms of OS, the iPhone 4 comes preinstalled with the newly released iOS 4, build 8A293. The iPhone 4 is Model A1332. Interestingly, that's a lower number than the A1337 iPad 3G.
Like the iPhone 3G and 3GS, there are two silver Phillips #00 screws at the bottom of the phone. In a departure from the design of the 3G and 3GS, removing the screws releases the rear case, not the front glass. This design makes switching out the rear panel trivial, but unfortunately means that replacing the iPhone 4 front panel will likely be rather challenging.
Removing rear panel gives us a pretty good look at the iPhone 4's innards. Holy battery! The inside of this thing is dominated by its juice-provider. It's pretty apparent that real estate was very limited inside the iPhone 4's 115.2 x 58.6 x 9.3 mm footprint. You can also see pressure contact on the inner face of the rear panel for what appears to be an antenna.
The 3.7V 1420 mAh Li-Polymer battery allows for up to 7 hours of talk time on 3G or up to 14 hours on 2G. The battery connector is different than the one in the 3G and 3GS. Fortunately, the battery is not soldered to the logic board. This will make battery replacement on the iPhone 4 fairly easy to accomplish.
The EMI shield comes off after five screws are removed to reveal lots of important connectors. Upon further inspection, it looks like the EMI shield actually acts as the Wi-Fi antenna. The long screw at the top and center grounds the antenna.
The logic board is heavily embedded under wires and EMI shields. While we're not too busy, let's talk RAM. Unlike the iPhone 3GS and iPad, which are both equipped with 256 MB, the iPhone 4 has a whopping 512 MB! The increase in RAM allows for a larger amount of cached data allowing for a smoother and faster user experience.
Behold a beauty in the iPhone 4: a rear-facing 5 MP camera with 720p video at 30 FPS, tap to focus feature, and LED flash. This is a huge upgrade from the 3.2 MP camera found in the iPhone 3GS.
Apple has integrated the UMTS, GSM, GPS, Wi-Fi, and Bluetooth antennas into the stainless steel inner frame. The dual purpose stainless steel inner frame/antenna assembly addresses possibly the two biggest flaws concerning previous iterations of the iPhone: continuous dropped calls and lack of reception. Apple has gone a step further and tuned the phone to utilize whichever network band is less congested or has the least interference for the best signal quality, regardless of the actual signal strength. Early reports suggest this feature, while buggy in its early stages, will greatly improve the phone's reliability on AT&T's fragile network.
So What Makes That Thing Tick!?
Lurking deep within the phone, the A4 processor, manufactured by Samsung, is the centralized unit that provides the iPhone 4 with the much needed computing power. Replacing the Samsung S5PC100 ARM A8 600 MHz CPU used in the 3GS, the new iPhone uses the ARM Cortex A8 core, much like its bigger sibling, the iPad. The iPad's A4 is clocked at 1 Ghz. The new Samsung Wave S8500 smartphone uses the same Cortex A8 core! Just to the left of the A4 package, the AGD1 is the new 3 axis gyroscope that we believe is designed and manufactured by ST Micro for Apple. The package marks on this device do not appear to be the currently available commercial part, L3G4200D.
• Skyworks SKY77542 Tx–Rx iPAC FEM for Dual-Band GSM/GPRS: 880–915 MHz and 1710–1785 MHz bands
• Skyworks SKY77541 GSM/GRPS Front End Module
• STMicro STM33DH 3-axis accelerometer
• TriQuint TQM676091
• Samsung K9PFG08 flash memory
• Cirrus Logic 338S0589 audio codec (Apple branded)
• AKM8975 - newest magnetic sensor that promises to improve the performance over the prior generation
• Texas Instruments 343S0499 Touch Screen Controller
• 36MY1EE NOR and mobile DDR
• Wi-Fi, Bluetooth, and GPS are all provided by Broadcom and located beneath EMI shields on the front side of the board
• Broadcom BCM4329FKUBG 802.11n with Bluetooth 2.1 + EDR and FM receiver
• Broadcom BCM4750IUB8 single-chip GPS receiver
And Talk?!
Up next we find the second microphone, which is used to cut out ambient noise and improve sound quality when talking on the phone. You can also see the ambient light sensor and the proximity sensor which are mounted right above the earpiece. The front-facing VGA camera. While the 5 megapixel camera on the rear of the iPhone 4 is ideal for video recording, the smaller camera on the front optimizes use of Apple's FaceTime for mobile-to-mobile video calls.
Apple is following in the footsteps of the Nexus One by using dual microphones to help improve audio quality and suppress background noise. Interestingly, the two microphones are positioned at the two far ends of the phone. The microphone at the top of the iPhone is most likely utilized for capturing background noise to be analyzed by internal circuitry and used to cancel any noise put into the main microphone other than the user's voice.
You can also see the ambient light sensor which adjusts the iPhone's brightness as lighting conditions change. The proximity sensor sits right next to the ambient light sensor. This will turn the display off when you bring the phone up to your ear thus preventing any touch interaction while it's pressed up against ear.
www.ifixit.com
Posted by Janine E. Mooney, Editor
November 22, 2011
Wireless Design & Development
