Envelope tracking power amplifier with dual-mode supply modulator for LTE applications

This paper presents an envelope tracking power amplifier (ET PA) using a dual-mode supply modulator for handset applications. The supply modulator has a combined structure with a linear amplifier and a switching amplifier. The dual-mode supply modulator operates in high power mode and low power mode by converting the supply voltage of the linear amplifier to 5 V and 2.5 V, respectively. For 1.74-GHz long term evolution signal with 10-MHz bandwidth and 6.44 dB peak-to-average power ratio, the ET PA delivers a power-added efficiency (PAE) of 39.8% and an evolved universal terrestrial radio access adjacent channel leakage ratio of −35.7 dBc at an average output power of 27 dBm. The ET PA also delivers a PAE of 22.6% at an average output power of 18 dBm, which is 6.6% higher than that of the conventional ET PA and 13.1% higher than that of the stand-alone PA.