一具有線性補償電路之2.4GHz CMOS功率放大器

Abstract

本篇論文主旨在設計一個具有線性補償電路之功率放大器，其規格設定為Bluetooth。所下三顆分別為: 用來比較用之傳統功率放大器、具有PMOS補償電路及共模消除電路之功率放大器及具有gm3線性補償電路之功率放大器。這三個晶片皆是使用標準點25微米1P5M 互補式金氧半導體製程，其中，具有gm3線性補償電路之功率放大器正在製作中。量測結果顯示，傳統功率放大器的晶片可以在2.7GHz的頻率下提供20.39 dBm的輸出功率，同時有著24%的效率;使用2.5V電源的情況下，功率放大器晶片之工作電流為156mA， 在輸出等於20dBm下，兩訊號(two-tones) IM3 量測值約為-16.26dBc，550kHz頻寬下ACPR值為21dB。由量測的結果可驗証，這個功率放大器的規格適合工作在短距離無線傳輸的應用上，而且可以符合Bluetooth class 1的輸出功率規格(20dBm)及線性度要求規格。但具有PMOS補償電路及共模消除電路之功率放大器由於打線電感(bondwires)效應變動影響，量測結果顯示出振盪現象產生，雖仍可量到輸出訊號及功率增益，對線性度而言，頻譜已經很髒無法量測，故無法測量出線性度特性。 由Post-Simulation可知，此兩種具有線性補償之功率放大器，在輸出訊號功率皆等於20dBm時，可以減少1~3dB的三階相互調變訊號(third-order intermodulation distortion, IM3) ，在有共模訊號(common-mode signal)存在的情況下，由於此兩電路可提供較高的共模抑制比(Common-mode rejection ratio, CMRR), 故可降低約3dB IM3值。

This thesis is proposed for designing a CMOS power amplifier with linear compensation. All designs are targeted on the standard of Bluetooth v1.0b. Three power amplifiers are conventional power amplifier, power amplifier with PMOS compensation and common-mode cancellation, and improved gm3 power amplifier. Two of these power amplifiers are designed, proposed, and measured. The improved gm3 power amplifier is in process. All are fabricated in a standard 0.25μm single-poly-five-metal CMOS process. The conventional power amplifier chip can provide 20.39dBm output power with 24% drain efficiency at 2.7GHz. The operating dc current of conventional one is 156mA from 2.5V power supply. At output power equal 20dBm, the IM3 under two-tone test is about -16.26dBc. The ACPR is about 21dB at 550kHz bandwidth. Through measured results, the performance of the proposed CMOS RF power amplifier has been verified to be well suitable for short-range communication applications and can meet Bluetooth output power level class 1(20dBm) and linearity specifications. Unfortunately, the chip with PMOS compensation and common-mode cancellation has oscillation phenomena since the design consideration non-proper. Although it still can measure out the output power and power gain, but the results are not correct enough. From post-simulation results it can be found that these two types of power amplifier with linear compensation circuit would decrease 1~3dB output third-order intermodulation distortion at output power level equal 20dBm. When a common-mode signal exists, these two types of PA can increase 3dB IM3 values because of high CMRR value.