Highly Linear Fully Integrated Wideband RF PA for LTE-Advanced in 180-nm SOI

A highly linear fully integrated RF power amplifier (PA) for advanced long-term evolution (LTE-advanced) is fabricated in a 180-nm standard silicon-on-insulator process. To improve the linearity, several harmonic traps are introduced to minimize the second- and third-order harmonics, and hence, the third-order intermodulation distortion (IMD3). The impact on the linearity of the RF PA of each of the harmonic controls is studied and simulated. Finally, both the linearity of a standalone RF PA and an RF PA with proposed linearity enhancement circuitry is investigated by comparing their measured IMD3. For an LTE uplink signal with 20-MHz signal bandwidth and a 64-QAM 8.7-dB peak-to-average power ratio, the RF PA achieves 21.7% power-added efficiency (PAE) with 11-dB gain while delivering an average output power of 22.4 dBm in LTE-band VII. Simultaneously, the RF PA obeys the stringent spectral mask and the -30-dBc adjacent channel leakage ratio linearity requirement and achieves an error vector magnitude of only 4.05%. The linearized wideband RF PA is also verified for LTE-band I and achieves similar performance from 1.9 to 2.8 GHz. Thanks to the applied linearization technique, the proposed RF PA is able to transmit an LTE-advanced (release 12) signal with a carrier-aggregated bandwidth up to 60 MHz while satisfying the linearity requirements. For a 40-MHz (2 × 20 MHz) and 60-MHz (3 × 20 MHz) LTE-advanced signal at band VII, the RF PA produces an average output power of 19.2 and 17.6 dBm while achieving a PAE of 17.2% and 13.7%, respectively.