A hybrid envelope modulator using feedforward control for OFDM WLAN polar transmitter

Author

Lee, Chih-Chang ; Chen, Chun-Jen ; Wu, Szu-Hsien

Author_Institution

SoC Technol. Center, Ind. Technol. Res. Inst., Hsinchu, Taiwan

fYear

2009

fDate

7-9 June 2009

Firstpage

141

Lastpage

144

Abstract

This paper presents a feedforward control for hybrid envelope modulator for applications in 802.11g OFDM WLAN polar transmitter. The feedforward control is constituted by hysteresis comparator and duplicate-linear amplifier that possess low power dissipation. For achieving high speed and high efficiency, the hybrid envelope modulator combines with a linear amplifier and a switch amplifier. Operational transconductance amplifier (OTA) and class-AB output stage are designed for linear amplifier as well as the buck converter is designed for switch amplifier. The chip has been fabricated in 0.35 mum SiGe process and occupies an area of 2 mm² including I/O pads. The die is packaged in LQFP and measurement results show that the output voltage range is from 0 to 3 V under 3.8 V power supply and drives a 5 Omega load up to 1.8 W of maximum output power with 95% of maximum efficiency.

Keywords

Ge-Si alloys; OFDM modulation; feedforward; modulators; radio transmitters; telecommunication control; wireless LAN; IEEE 802.11g; OFDM WLAN polar transmitter; SiGe; buck converter; duplicate-linear amplifier; efficiency 95 percent; feedforward control; hybrid envelope modulator; hysteresis comparator; operational transconductance amplifier; power 1.8 W; size 0.35 micron; voltage 0 V to 3 V; voltage 3.8 V; Buck converters; Hysteresis; OFDM modulation; Operational amplifiers; Power dissipation; Silicon germanium; Switches; Transconductance; Transmitters; Wireless LAN;

fLanguage

English

Publisher

ieee

Conference_Titel

Radio Frequency Integrated Circuits Symposium, 2009. RFIC 2009. IEEE

Conference_Location

Boston, MA

ISSN

1529-2517

Print_ISBN

978-1-4244-3377-3

Electronic_ISBN

1529-2517

Type

conf

DOI

10.1109/RFIC.2009.5135508

Filename

5135508