| Summary: | 碩士 === 國立臺北科技大學 === 電腦與通訊研究所 === 100 === This thesis aims to design a K-band RF front-end using a standard mixed-signal/RF 0.18um CMOS 1P6M process provided by TSMC. The presented circuits including an image/interference-reject low noise amplifier (IR-LNA), a second-order bandpass filter (BPF) with three transmission zeros, and a 90 degree coupler using high slow-wave transmission lines. The IR-LNA consists of a cascode LNA and an image/interference rejection filter. A Q-enhanced technique called semi-active inductor using a tapped-inductor and a NMOS transistor is proposed to improve the image rejection. In order to realize the Q-enhanced inductor, a negative resistance circuit is employed to compensate the resistive losses of inductors. Similarly, the Q-enhanced technique is also employed to reduce the resistive losses of the proposed 2nd BPF. Moreover, a feedback inductor is added between input and output ports to achieve three transmission zeros offering high selectivity. Finally, the 90 degree coupler using high slow-wave transmission lines with superior performances is presented. The characteristics of the guiding structure feature high Q factor and high slow-wave factor by changing the geometry in the ground plane.
Measured results: the measured gain, NF, and P1dB at 22.8GHz of the LNA are 10.46dB, 4.73dB, and -12.63dBm, respectively. The LNA including the notch filter consumes 14.13-mW power consumption. Furthermore, it achieves a 33.46-dB image/interference rejection at 17.9 GHz. The measured insertion loss, noise figure, P1dB, and power consumption of the 2nd BPF are 1.65dB, 13.2dB, -3.5dBm, and 4.2mW at 23.5 GHz. Additionally, the filter achieves a 13.2-dB return loss with a 17% 3-dB bandwidth, and the rejection levels at these transmission zeros are greater than 15.2dB. Compared with conventional image/interference rejection filters and bandpass filters, the two designs combined with the proposed semi-active inductors not only reduce the insertion loss in filters, but also show the better rejection levels. Finally, the 90 degree coupler using the proposed slow-wave transmission line technique shows a low-loss and miniaturized design. The compact area is 0.352 mm2, and the size is merely 0.00225 square wavelenth at 24GHz.
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