Title :
Analysis and optimization of third order intermodulation distortion mechanisms in AlGaAs/GaAs heterojunction bipolar transistors
Author :
Samelis, A. ; Pavlidis, D.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Michigan Univ., Ann Arbor, MI, USA
Abstract :
The third-order intermodulation distortion (IMD3) mechanisms of HBTs (heterojunction bipolar transistors) are analyzed using Volterra series theory. The third-order nonlinear currents generated by the device nonlinearities are evaluated for this purpose. Second-harmonic loading is addressed in view of IMD3 optimization while, at the same time, maintaining high gain through conjugate matching at the fundamental frequency. It is shown that IMD3 depends on a complex process involving interactions between various nonlinear elements and is highly sensitive to C/sub bc/ generated nonlinear current. The interaction of the latter with the other HBT elements significantly affects the IMD3. Optimum IMD3 occurs at high second-harmonic reflection coefficients corresponding to open load conditions. An IMD3 improvement of up to 27 dBm can be obtained by proper loading.<>
Keywords :
III-V semiconductors; aluminium compounds; equivalent circuits; gallium arsenide; heterojunction bipolar transistors; intermodulation; semiconductor device models; solid-state microwave devices; AlGaAs-GaAs; HBTs; IMD analysis; IMD3; Volterra series theory; conjugate matching; device nonlinearities; heterojunction bipolar transistors; large signal modelling; optimization; second harmonic loading; second-harmonic reflection coefficients; third order intermodulation distortion; third-order nonlinear currents; Character generation; Contracts; Frequency; Gallium arsenide; Heterojunction bipolar transistors; Intermodulation distortion; Linearity; Reflection; Solid state circuits; Transfer functions;
Conference_Titel :
Microwave Symposium Digest, 1992., IEEE MTT-S International
Conference_Location :
Albuquerque, NM, USA
Print_ISBN :
0-7803-0611-2
DOI :
10.1109/MWSYM.1992.188321
