As many observers point to a fourth quarter release for Apple's anticipated iPhone 5, analysis of the current HTC Thunderbolt lends clues to what can be expected.

Of particular interest is fact that the Thunderbolt is the one of the leading 4G -- or post 3G networking using phones, and the top seller at Verizon.

The 4G Long Term Evolution (LTE) wireless chips required for the faster speeds in the Thunderbolt cost an extra $39.75, according to industry researcher IHS.

It estimates based on its tear down of the device. That brought the total cost to $262, making it highest BOM [bill of materials] cost of any smartphone IHS has ever torn down, rivaling the expense of media tablets.

This means that Apple could face significant hurdles rolling 4G technology into its own forthcoming iPhone 5.

Either Apple could chooses to forgo 4G technology all together, or make some compromises because of the size and price of the chip.

First, the iPhone's minuscule printed circuit board (PCB) will have to grow in size in order to support the first-generation LTE baseband processor as well as all the supporting chipset, explained firms senior analyst, Wayne Lam.

Second, the next iPhone's BOM value certainly will increase substantially compared to the iPhone 4 if LTE is implemented in the same manner as in the HTC Thunderbolt.

The current BOM for the iPhone 4  costs $171.35 to make, the firm estimates, based on units examined in February. That would rise to $211.10 using the same silicon for 4G as is seen in the Thunderbolt, significantly cutting down on margins and potentially raising the shelf-price of the device.

Apple executives have publically complained about the poor designs of current LTE chips. With that, Apple could opt to use someone else entirely.

Qualcomm's SnapDragon MSM8960 is a newer version of the the 8655 part used in the Thunderbolt.

 It combines LTE, the EVDO standard for existing CDMA networks, and the GSM standard used at AT&T, in one chip.

I would imagine the caveat would have to be added that strict cost of components may vary between Apple and HTC, given Apple's purchasing power in the semiconductor market, Lam says.