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Unformatted text preview: 1290 IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 34, NO. 9, SEPTEMBER 1999 Design of a 32.7-GHz Bandwidth AGC Amplifier IC with Wide Dynamic Range Implemented in SiGe HBT Kenichi Ohhata, Toru Masuda, Eiji Ohue, and Katsuyoshi Washio Abstract— A wide-bandwidth automatic gain control (AGC) amplifier IC was developed using a self-aligned selective-epitaxial SiGe heterojunction bipolar transistor (HBT). A transimpedance load circuit was used, and its damping factor was optimized to achieve a wide bandwidth of 32.7 GHz. Capacitor peaking was introduced to the second variable-gain amplifier in order to obtain a wide gain dynamic range of 19 dB. The amplifier IC has a noise figure of 18 dB and an eye pattern at 25 Gb/s. Index Terms— Automatic gain control (AGC) amplifier, opti- cal transmission system, SiGe heterojunction bipolar transistor (HBT). I. INTRODUCTION T HE recent popularity of the Internet and multimedia communications has greatly increased the demand for high-speed communication systems. Optical transmission sys- tems operating at 10 Gb/s have been developed for large capacity networks to meet this demand, and a transmission system as fast as 40 Gb/s is just now being developed. Several component IC’s for a 40-Gb/s system have been reported, which use various high-speed devices such as Si bipolar tran- sistors , heterojunction bipolar transistors (HBT’s) based on SiGe – and InP/InGaAs , GaAs MESFET’s , and high electron mobility transistors (HEMT’s) . SiGe HBT is one of the most promising of these devices because it is inexpensive and highly reliable. Automatic gain control (AGC) amplifier IC’s are key com- ponents in optical-fiber transmission systems. Both wide band- width and wide dynamic range are indispensable for an AGC amplifier IC. A packaged AGC amplifier with a bandwidth of 26 GHz and a dynamic range of 6 dB, developed using AlGaAs/GaAs HBT’s with a cutoff frequency of 76 GHz, has been reported ; however, both its bandwidth and dynamic range were insufficient for the 40-Gb/s system. In general, the minimum bandwidth needed in a bit rate is about 3/4 ; therefore, a bandwidth of more than 30 GHz is required in a 40-Gb/s system. We recently reported on a Si-based AGC amplifier having a wide bandwidth of 32.7 GHz and a dynamic range of 19 dB , which uses self-aligned selective-epitaxial SiGe HBT’s . Manuscript received January 5, 1999; revised March 24, 1999. K. Ohhata is with Hitachi Device Engineering Co., Ltd., Tokyo 185-8601 Japan (e-mail: [email protected]). T. Masuda, E. Ohue, and K. Washio are with the Central Research Laboratory, Hitachi, Ltd., Kokubunji, Tokyo 185-8601 Japan....
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This note was uploaded on 08/06/2008 for the course ECE 145 taught by Professor Rodwell during the Fall '07 term at UCSB.
- Fall '07