Title :
A novel SiGe BiCMOS variable-gain active predistorter using current steering topologies
Author :
Tsai, Jeng-Han ; Huang, Tian-Wei
Author_Institution :
Dept. of Electr. Eng., Nat. Taiwan Univ., Taipei, Taiwan
Abstract :
This paper presents the novel design of a 2.4-GHz variable-gain active predistorter (PD) using a 0.35-μm SiGe BiCMOS technology. Current steering topologies are selected for this design to provide dual functions of: (1) an active predistorter for power amplifier linearization; and (2) a variable gain amplifier (VGA) for transmitter power control. Unlike other traditional "passive" predistorters, this active predistorter does not need an additional buffer amplifier to compensate the loss. Furthermore, through the bias voltage control in the low current region, the amount of gain expansion from this predistorter becomes programmable, to compensate for the PA non-linearity. Finally, this variable-gain predistorter could be used as a VGA in a multi-stage power amplifier design and it is well suitable for RF-SOC applications. The PA experimental results of 16-QAM modulated signals show that the compressed constellation can be uniformly spread out into a "square", the spectral re-growth is suppressed by 7-9 dB, and the EVM can be reduced from 9.9 % to 5.7 %.
Keywords :
BiCMOS analogue integrated circuits; Ge-Si alloys; UHF integrated circuits; UHF power amplifiers; linearisation techniques; semiconductor materials; 0.35 micron; 16-QAM modulated signals; 2.4 GHz; BiCMOS predistorter; EVM reduction; PA nonlinearity compensation; RFIC; SiGe; VGA; compressed constellation uniform spreading; current steering topology; low current region bias voltage control; power amplifier linearization; programmable gain expansion; spectral re-growth suppression; transmitter power control; variable gain amplifier; variable-gain active predistorter; BiCMOS integrated circuits; Constellation diagram; Gain; Germanium silicon alloys; Power amplifiers; Power control; Silicon germanium; Topology; Transmitters; Voltage control;
Conference_Titel :
Radio Frequency Integrated Circuits (RFIC) Symposium, 2004. Digest of Papers. 2004 IEEE
Print_ISBN :
0-7803-8333-8
DOI :
10.1109/RFIC.2004.1320682