Browsing by Author "Teng, Ya-Hui"

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2.4/5.7-GHz CMOS Dual-Band Low-IF Architecture Using Weaver-Hartley Image-Rejection Techniques
(2009-03-01)
Meng, Chin-Chun
;
Wu, Tzung-Han
;
Syu, Jin-Siang
;
Yu, Sheng-Wen
;
Tsung, Kuan-Chang
A 2.4/5.7-GHz dual-band Weaver-Hartley architecture, using 0.18-mu m CMOS technology, is demonstrated in this paper. The 2.4-GHz signal is set to be the image signal when the desired signal is at 5.7 GHz, and vice versa. Since the Weaver and Hartley systems are combined into this architecture, the demonstrated architecture rejects not only the first image signal, but also the secondary image signal. The image-rejection ratios of the first image signal and the secondary image signal are better than 40 and 46 dB, respectively. In this paper, a diagrammatic explanation is employed to obtain the image-rejection mechanisms of the Weaver-Hartley architecture.
Characteristics of GaAs transformers for RFIC applications
(2008-11-01)
Meng, Chinchun
;
Teng, Ya-Hui
;
Syu, Jin-Siang
;
Lin, Yi-Chen
;
Jhong, Jhin-Ci
In this article, stacked transformers, coupling stacked transformers, interleave transformers, and symmetrical transformers on GaAs substrate are systematically studied. Two kinds of stacked transformer are under study. One has the symmetrical electric property while the other one has a better quality factor for the primary port. The stack transformers have achieved the highest coupling coefficient (similar to 0.9) at the cost of lower self-resonance frequency. The interleave transformers have the identical electrical properties for the primary and the secondary ports. However, the layout is incompatible with the differential operation. Oil the other hand, the symmetrical transformer is compatible with the differential operation (aid call have the center-tapped biasing option. The data established here provides a useful design library for the GaAs RFIC. (C) 2008 Wiley Periodicals, Inc.
Characteristics of Integrated RF Transformers on GaAs Substrate
(2007)
Meng, Chinchun
;
Teng, Ya-Hui
;
Lin, Yi-Chen
;
Jhong, Jhin-Ci
;
Yen, Ying-Chieh
Stacked transformers, coupling stacked transformers, interleave transformers and symmetrical transformers on GaAs substrate are systematically studied in this paper. Two kinds stacked transformer are under study. One has the symmetrical electric property while the other one has a better quality factor for the primary port. The stack transformers have achieved the highest coupling coefficient (similar to 0.9) at the cost of lower self-resonance frequency. The interleave transformers have the identical electric properties for the primary and the secondary ports. However, the layout is incompatible with the differential operation. On the other hand, the symmetrical transformer is compatible with the differential operation and can have the center-tapped biasing option. The data established here provide a useful design library for the GaAs RFIC.
Large Improvement in Image Rejection of Double-Quadrature Dual-Conversion Low-IF Architectures
(2010-07-01)
Syu, Jin-Siang
;
Meng, Chin-Chun
;
Teng, Ya-Hui
;
Liao, Hua-Yu
;
電機工程學系
The reasons for a degradation of image-rejection performance in double-quadrature-double-quadrature and single-quadrature-double-quadrature dual-conversion low-IF downconverters are fully discussed in this paper. Polyphase filters (PPFs) are inserted at proper positions to minimize the effects of device/signal mismatches, and thus improve the image rejection without calibration. Both a 0.35-mu m SiGe heterojunction bipolar transistor 5.2-GHz double-quadrature-double-quadrature downconverter with an RF PPF and a 0.18-mu m CMOS 2.2/4.8-GHz single-quadrature-double-quadrature downconverter with a switched-band low-noise amplifier (LNA) and a narrowband inter-stage PPF are demonstrated. Compared with our previous work, the 5.2-GHz downconverter achieves a 15-dB improvement in image-rejection ratio (IRR) of the first image signal (IRRR(1)) even without a pre-selection filter or LNA. Additionally, the dual-band downconverter has a 25-dB improvement in IRR of the second image signal (IRRR(2)), which nearly reaches the theoretical limit of a four-stage PPF covering 20-40 MHz.
X-Band Weaver-Hartley Low-IF Downconverter With a Resonant LC Load
(2009)
Syu, Jin-Siang
;
Meng, Chinchun
;
Teng, Ya-Hui
;
Huang, Guo-Wei
;
電子工程學系及電子研究所
An X-band Weaver-Hartley dual-conversion low-IF downconverter is demonstrated in this paper using 0.35-mu m SiGe heterojunction bipolar transistor (HUT) technology. The first image signal is shifted away from the IF band due to the complex Weaver architecture while the second image signal is eliminated by a polyphase filter in the following Hartley architecture. In this work, a resonant LC load is employed at the first-stage mixer to improve both gain and linearity. As a result, the demonstrated downconverter achieves a conversion gain of 8 dB, single-sideband noise figure of 18 dB, IP(1dB) of -9 dBm, and IIP(3) of 0 dBm, respectively, while consuming 75 mW at a 3.3-V supply. Moreover, the first and second image-rejection ratios are better than 43 and 40 dB when IF frequency ranges from 15 to 100 MHz.