Design of Wideband Power Amplifier for Small Cell Applications

本研究以Chebyshev低通阻抗轉換網路為匹配架構，設計C類寬頻功率放大器(power amplifier，簡稱PA)，涵蓋LTE(Long Term Evolution)頻段1至頻段4。其中匹配電路的L、C元件，以高、低阻抗微帶線的全傳輸線式匹配，和以高阻抗接地共面波導與SMD(Surface Mount Device，簡稱SMD)0402電容的半傳輸線式匹配兩種方式等效。量測此兩種匹配形式的寬頻PA，於一階匹配阻抗點相近的情況下，當輸入為單頻CW(continuous-wave)訊號且功率為18 dBm時，在頻段1.4GHz至2.6GHz內輸出功率在25-29 dBm之間，汲極效率在50-75%之間。半傳輸線式匹配寬頻PA較本研究的全傳輸線式匹配寬頻PA有較好的諧波抑制效果，比較匹配電路面積，半傳輸線式匹配PA相較於本研究的全傳輸線式匹配PA減少了91%的面積。In this research, Chebyshev type of low-pass impedance transformation network is chosen as the matching structure for the design of broadband class C power amplifiers (PAs) which can cover LTE Band I to Band IV. To approximate inductors and capacitors in the low pass transformation network, high- and low- impedance microstrip lines are used in the all-distributed matching type of PA, and high CPWG(coplanar waveguide with ground) and SMD 0402 capacitors are used in the semi-lumped matching type of PA. With similar first order input and output impedances between the two matching types of PAs, the experiment results show that both of the PAs are realized from 1.4 to 2.6 GHz(60%) with a measured drain efficiency of 50%-75% and output power of 25-29 dBm. The semi-lumped matching type of PA has better harmonic suppression than the all-distributed matching type of PA, and furthermore, the area of the semi-lumped matching type of PA circuit is smaller than the one of the all-distributed matching type of PA by 91%