压焊点底下介质容抗对HBT高频性能影响

Impact of Capacitive Dielectric Material under the Pads on High-Frequency Characteristics in HBTs

在对采用了同一流片相同制备工艺制得的两个异质结双极晶体管(HBT)高频特性实验测量数据分析比较的基础上,探讨了压焊点(Pad)底下介质容抗对HBT高频性能的影响,结论表明:Pad底下的介质容抗对HBT的高频性能影响比较明显,且高频段[-20dB/decade]直线外推fT、fMAX的规律由于介质容抗的存在会造成较大的误差可不再有效,因而等效电路模型需作相应的修正。

Based on the analysis to the measured data for the high-frequency characteristics of two heterojunction bipolar transistors（HBTs） with the same fabricated process,the influence of capacitive dielectric material under the Pads on the high-frequency characteristics in HBTs has been investigated.The conclusion is made that the capacitive reactance of dielectric material under Pads can have great impacts on the RF performance of HBTs,which should be taken into account to the HBT equivalent circuit modeling,and that the extrapolate rule for fT,fMAX of the –20dB/decade extending line may have enough erroneous because of the capacitive reactance of the dielectric material under Pads.