2.2 A fully integrated reconfigurable wideband envelope-tracking SoC for high-bandwidth WLAN applications in a 28nm CMOS technology

Envelope tracking (ET) has become popular for enhancing battery life in mobile communication devices that employ high peak-to-average power ratio (PAPR) signals. Most of the published ET systems have focused either on narrow-bandwidth standards, 20MHz WLAN, or LTE [1-3]. However, as the demand for higher bandwidths and data-rates increases, so does the need for wideband ET solutions. Furthermore, to support modulations with different PAPR and transmit powers, the PA will likely require seamless switching between a continuous ET mode and a fixed-supply mode (as with a low drop-out regulator, i.e. a LDO). Hence, fast reconfigurability is needed, which most published ET systems lack. This paper describes a fully integrated, reconfigurable WLAN ET system with digital baseband in a 28nm CMOS technology for bandwidths up to 40MHz. The ET modulator directly interfaces with a battery (Vbat) and is fully integrated within a complete WLAN transceiver with RF, digital, and frequency synthesizer circuitry.