一种正电控制大衰减量的6bit单片数控衰减器

Positive-Bias-Controlled MMIC Digital Attenuator with Large Attenuation

分析了单片数控衰减器的衰减原理,设计了一款DC～2 GHz的大衰减量的6 bit数控衰减器。并通过数模混合设计,采用基于GaAs工艺的场效应管驱动器结构将正TTL电平转换为衰减器负的控制电平,成功实现了正电控制,对单片电路进行了仿真与优化,采用GaAs工艺技术完成了流片。测试结果表明,在DC～2 GHz频带内,衰减步进1 dB,最大衰减量63 dB,插入损耗小于1.7 dB,衰减精度小于±0.1 dB@1 dB～4 dB;小于±0.8 dB@8 dB～32 dB;小于±1.3 dB@48 dB～63 dB,两个端口在所有态下的驻波比小于1.2∶1。单片数控衰减器芯片尺寸为3.0 mm×2.0 mm,控制电压为0和5 V。

A 6 bit digital attenuator with large attenuation of DC - 2 GHz was designed and the attenuation principle of monolithic digital attenuator was analyzed. Through the digital-analog hybrid design method, TTL level was converted to negative control level by a GaAs FET driver, positive-bias control was realized. The attenuator circuit fabrication based on the GaAs technology. Test results show that the attenuator works from DC to 2 GHz. It has a 63 dB attenuation range in 1 dB increments, and reference state insertion loss less than 1.7 dB. The attenuation accuracy is less than ±0. 1 dB from 1 dB to4 dB, less than ＋0.8 dB from 8 dB to 32 dB, less than ±1.3 dB from 48 dB to 63 dB and the voltage standing wave ration （VSWR） of the two ports is less than 1.2：1 in all states. The size of the final circuit is 3.0 mm - 2.0 mm. The control voltages are 0 V and 5 V.