Apple's iPhone 4 shares many components with the iPad
Apple iPad screen resolution is only 1024 by 768
Apple A4 processor found in iPad and iPhone 4
Apple’s latest iPhone 4 contains many of the same components at the new iPad including Apple’s A4 processor although the iPhone uses the latest package-on-package with 512 Mbytes of Mobile DDR SDRAM from Samsung. That doubles on-chip memory by a factor of 2. Packing everything into the iPhone 4 is the usual phone design challenge but is it surprising how much similarity to the iPad other than screen size. The iPad is 9.7-in with a resolution of 1024 by 769 versus whereas the iPhone is only 3.5–in but with a resolution of 960 by 640. This actually makes the iPhone 4 a crisper display with a higher pixel density. The iPhone 4 uses a Low-Temperature Polysilicon (LTPS) and In-Plane Switching (IPS) technology LCD display.
From some perspectives, the iPhone is significantly more powerful than the iPad given not one but two cameras on the iPhone. The main OmniVision OV5650 5-Mpixel camera has a 5x zoom and has an LED flash. The camera on the same side as the display has a VGA resolution of 640 x 480 and is designed for video conferencing. Texas Instruments provides the touch screen controller for the iPhone 4 versus the less expensive three chip solution used in the iPad.
iSupply estimates that the iPhone bill of materials (BOM) runs about $187 in parts. The BOM for the first iPhone was $217. A detailed teardown was done by Chipworks that delves down to the package and die markings.
The iPhone 4 brings the positioning support from the iPad including STMicroelectronics L3G4200D digital gyroscope and LIS331DLH accelerometer. 3D Accelerometers are common in smartphones but this is the first gyroscope to be included with a phone. The AKM AK8975 magnetic compass sensor has been improved compared to the iPad.
Infineon continues to provide the baseband and transceiver chips with quad-band GSM support. The Broadcom BCM4329 delivers low power 802.11n, Bluetooth, and FM radio support. Broadcom also supplies the GPS chip, the BCM4750. Audio support comes from Cirrus Logic’s 343S0589. The iPhone 4 has a 1400mAh lithium ion battery.
Sharing components obviously makes the phone less expensive for Apple to build. The continuity between platforms also makes it easier for developers to target both the iPad and iPhone. In general, they only differ in the number of pixels on the display and they are pretty close on that count.