Lightly doped emitter HBT for low-power circuits

Dept. of Electr. Eng. & Comput. Eng., California Univ., San Diego, La Jolla, CA
IEEE Microwave and Guided Wave Letters 12/1997; 7(11):377 - 379. DOI: 10.1109/75.641426
Source: IEEE Xplore


We report an approach to reduce the base-emitter capacitance in
AlGaAs-GaAs heterojunction bipolar transistors (HBT's) by adding a
lightly doped emitter (LDE) region together with appropriate planar
(δ) doping region to a conventional base-emitter junction. This
improves both the ft and β for low collector current
density (Jc) operation while preserving the high peak ft
at high Jc. When applied to a current mode logic
128/129 programmable prescaler, the LDE HBT results in a reduction in
power dissipation and improved bandwidth without any circuit

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