From Anantech:
"Band 4 (AWS) could essentially be supported with the power amplifiers and transceiver that already are onboard the Nexus 4,"
AnandTech - Google Nexus 4 Review - Google's new Flagship
Also, ""According to Qualcomm's data sheet the MDM9215 is an LTE modem (LTE FDD/TDD CAT 3, SVLTE-DB, Release 9 DC-HSPA+, TD-SCDMA, GSM/GPRS/EDGE, EGAL"). All the MDM92xx and MDM96xx Gobi chips have LTE. In fact, the MDM9215m specifically is the same modem used in the One X- which clearly does have LTE. What is more commonly claimed is that the Nexus 4 lacks an LTE amplifier. Yet Avago Technologies states that their ACPM-7251 amp supports "UMTS Dual-Band (Band1-UMTS & LTE and Band5 UMTS & LTE)". Again, a chip also used in the One X . Also present are Avago A5702 and A5704 LTE/UMTS power amps."