Abstract
A linear-switch mode hybrid envelope tracking (ET) supply modulator utilizing adaptive biasing and gain enhanced current mirror operational transconductance amplifier (OTA) with class AB output stage in parallel with a switching regulator is presented. In comparison to a conventional OTA design with similar quiescent current consumption, proposed approach improves positive and negative slew rate from 50 to 93.4 V/μs and-87 to-152.5 V/μs , respectively, dc gain from 45 to 67 dB while consuming same amount of quiescent current. The proposed hybrid supply modulator achieves 83% peak efficiency, power-added efficiency (PAE) of 42.3% at 26.2 dBm for a 10-MHz 7.24-dB peak-to-average power ratio (PAPR) long-term evolution (LTE) signal and improves PAE by 8% at 6 dB back off from 26.2-dBm power amplifier (PA) output power with respect to fixed supply. With a 10-MHz 7.24-dB PAPR quadrature-phase shift keying LTE signal the ET PA system achieves adjacent channel leakage ratio (ACLR) of-37.7 dBc and error vector magnitude (EVM) of 4.5% at 26.2-dBm PA output power, while with a 10-MHz 8.15-dB PAPR 64QAM LTE signal the ET PA system achieves ACLR of-35.6 dBc and EVM of 6% at 26-dBm PA output power without digital predistortion. The proposed supply modulator core circuit occupies 1.1-mm2 die area, and is fabricated in a 0.18-$\mu \text{m}$ CMOS technology.
Original language | English (US) |
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Article number | 7888538 |
Pages (from-to) | 3245-3256 |
Number of pages | 12 |
Journal | IEEE Transactions on Microwave Theory and Techniques |
Volume | 65 |
Issue number | 9 |
DOIs | |
State | Published - Sep 2017 |
Keywords
- Adaptive biasing
- envelope tracking (ET)
- gain enhancement
- high slew rate
- long-term evolution (LTE)
- power amplifier (PA)
ASJC Scopus subject areas
- Radiation
- Condensed Matter Physics
- Electrical and Electronic Engineering