Title :
A DC-21 GHz Low Imbalance Active Balun Using Darlington Cell Technique for High Speed Data Communications
Author :
Weng, Shou-Hsien ; Chang, Hong-Yeh ; Chiong, Chau-Ching
Author_Institution :
Dept. of Electr. Eng., Nat. Central Univ., Jhongli, Taiwan
Abstract :
A DC-21 GHz low imbalance active balun using a 2 mum InGaP/GaAs HBT process is presented in this letter for high speed data communications. A Darlington cell is adopted to enhance 3 dB bandwidth of the proposed active balun. A feedback capacitor is designed to compensate the phase error between differential output ports caused by the different number of stages. The proposed active balun achieves a broad bandwidth of 21 GHz, an average small signal gain of 2.5 dB, a maximum amplitude imbalance of 1.2 dB, and a phase error of less than 5deg. The measured group delays of the balun are lower than 30 ps with low variation. Moreover, an eye diagram with a pseudorandom bit stream of up to 12.5 Gbps is presented. The active balun is appropriate for high speed data communications due to its low imbalance and group delay.
Keywords :
III-V semiconductors; baluns; data communication; gallium arsenide; heterojunction bipolar transistors; high-speed techniques; indium compounds; Darlington cell technique; HBT process; InGaP-GaAs; bandwidth 21 GHz; feedback capacitor; gain 2.5 dB; group delay measurement; high-speed data communication; low-imbalance active balun; size 2 mum; Active balun; MMIC; darlington cell; heterojunction bipolar transistor (HBT); microwave;
Journal_Title :
Microwave and Wireless Components Letters, IEEE
DOI :
10.1109/LMWC.2009.2032017