適用於802.11a/b/g 無線區域網路之CMOS前端發射器設計

Abstract

這篇論文依據IEEE 802.11a/b/g standard的規範，提出雙頻前端發送器的規格。同時採用聯電 CMOS 0.18微米混合信號製程，分別針對高線性度及低功率的考量完成兩個5GHz直接轉換(Direct-Conversion)前端發射器設計。量測結果顯示，高線性度的前端發射器在低頻(BB/1MHz)信號及本地振盪(LO/5.25GHz)輸入下，升頻後輸出之高頻(RF/5.251GHz)信號，可獲得功率轉換增益8.6dB，同時在輸入功率-5.3dBm之1dB壓縮點(P1dB)有最大輸出功率2.3dBm，及擁有6.3 dBm IIP3及13 dBm OIP3的高線性度。此電路在1.8V供應電壓下消耗68mW功率，可滿足802.11a 54Mb/s 64QAM信號傳送mask的要求。最後，並以此5GHz電路模組完成了雙頻前端發送器設計，該發送器為了節省功率及降低面積，共用單一一個升頻混波器加上兩個前端放大器分別對5GHz及2.4GHz頻段信號作放大，模擬結果分別在2.4GHz操作下達到7dB轉換增益，並在輸入功率1dB壓縮點(P1dB)-5dBm下有最大輸出功率1dBm，而在5.25GHz操作下達到7.1dB轉換增益，並在輸入功率1dB壓縮點(P1dB)-5.3dBm下有最大輸出功率0.4dBm，皆符合雙頻發送器的規格規範，該電路在1.8V供應電壓下消耗44mW功率。

Based on IEEE 802.11a/b/g standards, the specification of dual-band transmitter front-end has been specified. Two 5GHz CMOS RF transmitters front-end have been implemented by UMC 0.18um CMOS mixed-mode technology. One is designed for high linearity while another is designed for low power applications. The transmitters adopted the same direct-conversion architecture and composed of a quadrature single-side band mixer and a pre-amplifier. With inputting 1MHz base band (BB) signals and 5.25GHz local oscillator (LO) signals, after up-conversing, the output frequency locates at 5.251 GHz. The measurement results exhibit that the TXFE for high linearity design achieves enough conversion gain of 8.6 dB for specification, and obtains high linearity performance of 6.3 dBm IIP3 and 13 dBm OIP3. Moreover, the maximum output power is 2.3dBm for input 1dB compression point of -5.3 dBm (P1dB). This transmitter could meets the transmit spectrum mask for 802.11a 54Mb/s, 64QAM signals with consuming 68mW at 1.8V power supply. Finally, based on this 5GHz transmitter architecture, the dual-band transmitter front-end has been proposed. To improve the power consumption and decrease the circuit area, a novel architecture adopted single mixer and followed by two pre-amplifiers. Simulation results indicate that this design achieves 7.0dB conversion gain, and obtains the maximum output power of 1dBm for -5dBm P1dB for 2.4 GHz operation while achieves 7.1dB conversion gain, and obtains the maximum output power of 0.4dBm for -5.7dBm P1dB for 5.25 GHz operation which could meet the specifications of dual-band transmitter front-end. This dual-band transmitter consumes only 44mW at 1.8 power supply.