Browsing by Author "Tseng, S. -C."

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Gain enhancement techniques for CMOS LNA and mixer
(2006-10-01)
Su, J. -Y.
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Meng, C. C.
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Li, Y. -H.
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Tseng, S. -C.
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Huang, G. -W.
Two major techniques for gain improvement of the CMOS low noise amplifier (LNA) and mixer are presented. First, the inductive interstage matching is applied to design a cascode amplifier for increasing the power transfer between the common source (CS) and common gate (CG) stages. Second, a super source follower (SSF) is utilized in a P-type micromixer for increasing the conversion gain of the mixer. A series of investigations are performed for demonstrating the feasibilities of the proposed techniques. The LNA and mixer designs based on the proposed techniques are realized using 0.35 im IP4M CMOS technology. Then their measured results are compared with those of a preliminary design, which fully integrates a conventional cascode amplifier and a P-type micromixer. The gain of the LNA is increased 2.1 dB and the noise figure is maintained at the same value of the preliminary design. On the other hand, the conversion gain of the super source follower (SSF) of the micromixer output is improved about 9.5 dB. Such improvements reveal great potential of the proposed design techniques on the gain enhancement for the LNA and mixer. Then, the measured results of the preliminary design show the return-loss of 25 dB, the isolation of better than 30 dB, and the conversion gain of 4.8 dB in the 2.4 GHz ISM hand. (C) 2006 Wiley Periodicals, Inc.
GaInP/GaAs HBT wideband transformer Gilbert downconverter with low voltage supply
(2008-01-17)
Tseng, S. -C.
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Meng, C. C.
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Wu, C. -K.
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電信工程研究所
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Institute of Communications Engineering
A low-voltage wideband downconverter along with an integrated transformer RF balun using the 2 mu m GaInP/GaAs HBT technology is demonstrated. This transformer is a symmetric type and plays a role as a single-to-differential balun. Without the parasitic between the transformer and the substrate, the transformer can work at higher frequencies. This transformer downconverter operates from 1.5 to 14 GHz with around 20 dB conversion gain and 1.8 GHz IF 3 dB bandwidth. The frequency range of the mixing operation is wide and covers the digital video broadcasting via satellite (DVB-S) bands. This mixer is therefore useful for DVB-S applications.
INTERCONNECTION LOSS FROM SUBSTRATE EFFECTS ON LNA PERFORMANCE AND DESIGN ACCURACY
(2009-01-01)
Tseng, S. -C.
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Meng, C. C.
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Liao, H. -Y.
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Lin, Y. -C.
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Teng, Y. -H.
A 5.2 GHz 0.18-mu m SiGe BiCMOS low noise amplifier is implemented with guided-wave interconnections in this letter. These interconnections reduce the substrate skin and proximity effects and hence are suitable for high frequency circuits. The guided interconnections bring 1.7-dB gain and 0.55-dB noise figure enhancement for the low noise amplifier. In addition, accurate and simple design methodology relies on the complete models of components and interconnections when the poststimulation from the rc extraction is not enough for the high,frequency circuit design. The measurement results give excellent agreements with the schematic simulation. (C) 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 144-146, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23968