| Summary: | 博士 === 國立成功大學 === 微電子工程研究所碩博士班 === 99 === Wireless telecommunications research has experienced a remarkable renaissance in the last decade. Low cost, low power and a compact-size are the essential requirements for modern RF frond-end systems. To accomplish a successful design that meets all of these requirements, circuit design techniques and advanced process technology are necessary.
In the RF frond-end system, low-noise amplifiers, baun, and oscillators are essential components. LNA is used to amplify RF input signals, and its performance must be kept sufficiently high to minimize the requirements for circuits’ parameters from the following stages. In research on LNA, the design, fabrication, and measured performance of LNAs operating at the S-band and UWB will be presented. In this dissertation, 2.4 GHz high linearity LNA with Image-rejection is proposed. The active filter is used for high selection of image band and reducing the chip size. The linearity of 2.4-GHz Image-Rejection LNA is improved by employing derivative superposition (DS) technique with PMOS auxiliary stage and rejecting the gm3 for high input third-order intercept point (IIP3). Then an UWB LNA using active shunt-feedback technique has been proposed. By employing active shunt-feedback technique, the UWB LNA achieves wideband input matching characteristic and uses fewer devices to reduce the chip size. The output matching of the proposed UWB LNA uses a center-tapped inductor for second-order matching design.
An ultra-wideband active balun using standard 0.18 μm CMOS process has been presented in chapter 4. The measurement shows that the active balun using parallel common-gate and common-source generates a 50 Ω real part and achieves wideband input matching from 3.1 GHz to 10.6 GHz. The phase behaviors are dominated by CS and CG. The amplitude imbalances are dominated by the bias and size of CG and CS and amplitude imbalances is less than 0.5 dB. In order to solve the issue of the active balun which is the high power consumption, the current-reused structure is used.
Finally, in chapter 5, CMOS second-order LC VCOs are designed and discussed. Two ways to design the LC tank with a high Q passive center-tapped inductor and an active inductor for IEEE 802.11a/b/g applications. A 5.37 GHz second harmonic suppressed cross-coupled CMOS VCO using circuit is presented firstly. Following, a high performance 2.33 GHz cross-coupled CMOS VCO using active filtering circuit is presented. Measured results demonstrate that low phase noise has been achieved by second harmonic suppression of cross-coupled CMOS VCO. The large-signal simulation results prove that the second harmonic signal distorts to the fundamental signal.
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