Ku波段微波单片集成电路6位数字衰减器设计

基于GaAs 0.25 μm增强/耗尽型（E/D）赝配高电子迁移率晶体管（pHEMT）工艺，研制了一款Ku波段6位数字衰减器微波单片集成电路（MMIC）。该6位数字衰减器由6个基本衰减位级联组成，可实现最大衰减量为31.5 dB、步进为0.5 dB的衰减量控制。采用简化的T型衰减结构，实现了0.5 dB和1 dB的衰减位。16 dB衰减位采用开关型衰减拓扑，在提高衰减平坦度的同时，有效降低其附加相移。测试结果表明，在12～18 GHz的频率内，数字衰减器衰减64态均方根误差（RMS）小于0.25 dB，附加相移为−0.5°～＋9.5°，插入损耗小于4.9 dB，输入输出驻波比均小于1.5∶1。芯片尺寸为3.00 mm×0.75 mm。该芯片电路具有宽频带、高衰减精度、小尺寸的特点，主要用于微波相控阵收发组件、无线通讯等领域。

Design of Ku-band 6 bit digital attenuator of microwave monolithic integrated circuit

A Ku-band 6 bit digital attenuator of microwave monolithic integrated circuit (MMIC) was developed based on GaAs E/D pseudomorphic high electron mobility transistor (pHEMT) process. The 6 bit digital attenuator was made up of six base states. It could obtain maximum attenuation of 31.5 dB with the attenuation step of 0.5 dB. 0.5 dB and 1 dB attenuation bits were realized by adopting simplified T-type structure. In the 16 dB attenuation bit, a switched-path-type topology was employed to improve the attenuation flatness and reduce the additional phase shift effectively. The measurement results show that in the range of 12−18 GHz, the 64-state root mean square (RMS) error is less than 0.25 dB, the phase variation is from −0.5° to ＋9.5°, the insertion loss is less than 4.9 dB and the input and output voltage standing wave ratios are both less than 1.5∶1. The chip size is 3.00 mm×0.75 mm. The MMIC chip has the characteristics of wide bandwidth, high attenuation accuracy and small size. It can be mainly used in fields such as microwave phased array radar transceiver components and communication.