Title :
Linearity characteristics of GaAs HBTs and the influence of collector design
Author :
Iwamoto, Masaya ; Asbeck, Peter M. ; Low, Thomas S. ; Hutchinson, Craig P. ; Scott, Jonathan Brereton ; Cognata, Alex ; Qin, Xiaohui ; Camnitz, Lovell H. ; D´Avanzo, Donald C.
Author_Institution :
Dept. of Electr. & Comput. Eng., California Univ., San Diego, La Jolla, CA, USA
fDate :
12/1/2000 12:00:00 AM
Abstract :
The linearity characteristics of GaAs heterojunction bipolar transistors (HBTs) are studied through measurement and analysis. Third-order intermodulation distortion behavior of HBTs is examined on devices with various epilayer designs and at various bias points, loads, and frequencies. Calculations from an analytical model reveal a strong bias and load dependence of third-order intercept point (IP3) on the nonlinearities from transconductance and the voltage dependence of base-collector capacitance. However, a simple model is not able to predict the fine details of IP3 with bias. A large-signal HBT model with an accurate description of the base-collector charge is shown to account for the measured trends. The base-collector charge function accounts for the modulation of base-collector capacitance with current, electron velocity modulation, and the Kirk effect (base pushout) for GaAs-based HBTs. A detailed study of the influence of collector design on linearity is also presented
Keywords :
III-V semiconductors; UHF bipolar transistors; equivalent circuits; gallium arsenide; heterojunction bipolar transistors; intermodulation distortion; microwave bipolar transistors; semiconductor device measurement; semiconductor device models; GaAs; GaAs HBTs; GaAs heterojunction bipolar transistors; IP3; Kirk effect; analytical model; base pushout; base-collector capacitance; base-collector charge; bias dependence; bias points; collector design; electron velocity modulation; epilayer designs; intermodulation distortion behavior; large-signal HBT model; linearity characteristics; load dependence; nonlinearities; third-order IMD behavior; third-order intercept point; transconductance; voltage dependence; Analytical models; Capacitance; Distortion measurement; Frequency; Gallium arsenide; Heterojunction bipolar transistors; Intermodulation distortion; Linearity; Transconductance; Voltage;
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
