What GPS IC do cell phones use
Usually the GPS in the phones are a) really integrated in the radio chipset and b) often software driven. I don't think a mere human could get his hands on such mass production/consumer tech.
By the way, and this could help with your module, most modules have their antenna undertuned so it will actually work at max performance only when in a plastic enclosure (the plastic is kinda part of the antenna system).
Of course, there are also just modules that suck:D