| Summary: | 碩士 === 長庚大學 === 電子工程學研究所 === 97 === The low noise amplifier (LNA) is one of the key sub-circuits in the front-end of the receiver. A 3.1-10.6 GHz low noise amplifier with feedback topology is proposed for Ultra-Wideband system in this thesis. The advantage of feedback topology is wideband, good stability and uniformity. We also used parallel LC to extend bandwidth and noise-canceling configuration to minimize the noise for achieving low power consumption, high gain and low noise.
The first stage is the capacitance-resistance feedback cascode topology that provides high gain, wider bandwidth, better stability and well reverse isolation. The middle stage is an inductor-capacitor parallel configuration (LB//CB) to pull up high frequency gain. The output stage is a simple current buffer that gives broadband out impedance of 50 for measurement purposes. Additionally, we also used the noise-canceling technique to minimize the noise for LNA circuit. The circuit is fabricated using 0.18 m CMOS technology for high gain, low power and low noise with a chip size 0.53 mm2 including the probe pads.
A CMOS UWB LNA with a feedback topology and noise-canceling technique has been designed. This UWB LNA exhibited a high 11 dB gain, low 3.6 dB NF, input reflect loss less than -6.5 dB, output return loss less than -14 dB and the input IIP3 is -7 dBm from 3.1 to 10.6 GHz, while only 10.3 mW power dissipation. The fabricated LNA satisfies UWB LNA system requirements.
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