Dual Bias Modulator for Envelope Tracking and Average Power Tracking Modes for CMOS Power Amplifier

Abstract

This paper presents a dual-mode bias modulator (BM) for complementary metal oxide semiconductor (CMOS) power amplifiers (PAs). The BM includes a hybrid buck converter and a normal buck converter for an envelope tracking (ET) mode for high output power and for an average power tracking (APT) mode for low output power, respectively. The dual-mode BM and CMOS PA are designed using a 0.18-㎜ CMOS process for the 1.75 ㎓ band. For the 16-QAM LTE signal with a peakto-average power ratio of 7.3 ㏈ and a bandwidth of 5 ㎒, the PA with the ET mode exhibited a poweradded efficiency (PAE) of 39.2%, an EVM of 4.8%, a gain of 19.0 ㏈, and an adjacent channel leakage power ratio of -30 ㏈c at an average output power of 22 ㏈m, while the stand-alone PA has a PAE of 8% lower at the same condition. The PA with APT mode has a PAE of 21.3%, which is an improvement of 13.4% from that of the stand-alone PA at an output power of 13 ㏈m.