超寬頻無線網路應用之低功率互補金氧半射頻前端接收器設計

Abstract

本論文針對超寬頻(UWB)無線網路應用提出低功率互補式金氧半(CMOS)射頻前端接收器之設計。本文提出之低雜訊放大器(LNA)採用兩級堆疊交錯調整之共射級放大器架構，其中兩級分別諧振於不同頻率，以達成低功耗和超寬頻之設計目標。經由0.18-μm CMOS 製程進行電路實作，量測出2.4G-9.4GHz的超大頻寬與7.3mW的極低功耗，同時具有9.7dB的最大功率增益、4.17dB的最低雜訊值和-3.5dBm的第三階互調線性度，驗證此兩級堆疊交錯調整之低雜訊放大器電路架構之優點。將此優異低雜訊放大器架構應用於超寬頻射頻前端接收器，加上被動式混波器，以符合低功耗與低閃爍雜訊之要求，並且增加一組偏壓接地之低雜訊基頻放大器，以補償被動式混波器之增益損失，進而有助於提升整體射頻接收器之雜訊績效。此超寬頻射頻前端接收器參考多頻帶正交頻率多重分割技術規格草案的第一頻帶組需求，運作頻帶從3GHz到5GHz，並以射頻/基頻共同模擬來驗證其低雜訊，高增益以及良好線性度之特性。

This thesis presents a low-power design of a direct conversion CMOS RF receiver front-end for ultra-wideband (UWB) wireless applications. To achieve low power consumption and wide operating bandwidth, the proposed LNA employing stagger tuning technique consists of two stacked common-source stages with different resonance frequencies. A circuit implementation in 0.18-μm CMOS process shows a 2.4-9.4-GHz bandwidth. The amplifier provides a maximum forward gain (S21) of 9.7 dB while drawing 7.3 mW from a 1.8-V supply. A noise figure as low as 4.17 dB and an IIP3 of –3.5 dBm have been measured. In this thesis, design optimization for the power-constrained stacked amplifiers in wide bandwidth applications is also presented. The novel topology of low power UWB LNA is applied to the RF front-end design for the UWB direct conversion receiver. In the RF front-end, a wideband passive mixer is designed for the purpose of low power, little flicker noise and high linearity after the LNA. A baseband amplifier biased at ground level is designed with consideration of low noise for compensating the gain loss of the passive mixer and consequently help improving overall noise performance of the receiver. The UWB receiver front-end referenced to the band group #1 of the Multi-Band OFDM with operation frequency range 3-5 GHz demonstrates low noise figure, low power, high gain, and wide bandwidth. It is also verified by a RF/Baseband co-simulation.