基于LC巴伦的伪差分功率放大器设计

Design of pseudo-differential power amplifier based on LC balun

为了在局部热点区域实现系统容量的成倍提升,需要能支持高频、大带宽工作的无线网络基础设施进行超密集组网,采用GaAs HBT工艺设计出适用于5G微基站的4.8~5.0 GHz三级高增益、大输出功率放大器。利用伪差分结构来抑制接地寄生电感的影响,通过片外低损耗LC巴伦完成单端与差分对之间的转换,结合有源自适应偏置网络与RC负反馈电路,并应用宽带匹配与预失真补偿的方法,基于ADS仿真验证了在中心频点4.9 GHz处可实现35.8 dB的功率增益与33.5%的峰值功率附加效率,且工作频带内能输出不低于35 dBm的饱和功率,可满足典型应用场景对网络信号无缝覆盖的要求。

In order to greatly improve the system capacity in local hotspots,the wireless communication infrastructure that can support high-frequency and wideband operation is required for ultra-dense networking.A 4.8~5.0 GHz three-stage high-gain and large-output power amplifier is designed using GaAs heterojunction bipolar transistor(HBT)process to be targeted for 5G microcells.The pseudo-differential structure is adopted to suppress the influence of ground parasitic inductance,while the conversion between single-ended and differential pairs is completed by off-chip low-loss LC balun.In conjunction with active adaptive bias network and RC negative feedback circuit,meanwhile applying the methods of wideband matching and predistortion compensation,ADS(Advanced Design System)simulations verified that the proposed power amplifier can achieve 35.8 dB power gain with 33.5%peak power-added efficiency at a center frequency of 4.9 GHz,and deliver not less than 35 dBm saturated output power in the operating band,which can meet the requirements of seamless coverage of network signals in typical application scenarios.