Wide-Bandwidth and High-Linearity Envelope- Tracking Front-End Module for LTE-A Carrier Aggregation Applications

Abstract

The envelope-tracking front-end module (ETFEM) consisting of an envelope-tracking supply modulator (ETSM), a dual-power-mode power amplifier (PA), and a single-pole-double-throw (SPDT) switch is proposed for the Long-Term Evolution-Advanced (LTE-A) intraband carrier aggregation (CA) signal. The linear stage of ETSM is implemented by introducing the dual-path crossover current-reuse mechanism to obtain the measured efficiency 79.6%, 76.4%, 74%, and 72.8% for 7.4-, 9.6-, 11.2-, and 12.3-dB peak-to-average-power ratio (PAPR) 16-QAM LTE-A CA signals with $1 \times 20$ , $2 \times 20$ , $3 \times 20$ , and $4 \times 20$ MHz bandwidths, respectively. A SiGe BiCMOS dual-power-mode PA with two output power modes is realized and incorporated with ETSM to improve the adjacent channel leakage ratio (ACLR) by 11.7, 7.9, and 4.7 dB and the error vector magnitude (EVM) by 7.1%, 6.1%, and 4.1% at 26.8-, 24.3-, and 21.7-dBm output powers for the LTE-A 16-QAM signals with $1 \times 20$ , $2 \times 20$ , and $3 \times 20$ MHz bandwidths at 1.95 GHz, respectively. The SPDT switch integrated with ETSM provides 0.3-dB power loss reduction, 1.1-dB ACLR improvement, and 0.7% EVM enhancement at 12-dBm average input power. The ETFEM operated at 12.5-dB PAPR 64-QAM LTE-A CA signal with $4 \times 20$ MHz bandwidth demonstrates that the improvements of 1.3-dB ACLR and 1% EVM at 13.1-dBm output power are achieved for the wide-bandwidth and high-linearity FEM applications.