Title :
Sub-ft gain resonance of InP/InGaAs-HBTs
Author :
Rohner, M. ; Willén, Bo ; Jäckel, H.
Author_Institution :
Electron. Lab., Swiss Fed. Inst. of Technol., Zurich, Switzerland
fDate :
2/1/2002 12:00:00 AM
Abstract :
Advanced npn-InP/InGaAs HBTs are often operated at high current levels for optimum high-speed performance. Because of velocity modulation effects, these transistors may operate in base-pushout although measurements of the cut-off frequency ft indicate the opposite. We show that the low mobility of the holes has a strong effect on the transistor operation in this regime, which is only revealed from a dynamic analysis: The unilateral power gain peaks far below ft followed by a -40 dB/dec roll-off. The effect was thoroughly analyzed and as a result, we present a simple equivalent circuit model that successfully describes transistors operating in pushout up to very high frequencies
Keywords :
III-V semiconductors; equivalent circuits; gallium arsenide; heterojunction bipolar transistors; hole mobility; indium compounds; semiconductor device models; InP-InGaAs; InP/InGaAs HBT; base-pushout; cut-off frequency; dynamic analysis; equivalent circuit model; gain resonance; high-frequency operation; high-speed operation; hole mobility; roll-off; unilateral power gain; velocity modulation; Cutoff frequency; Density measurement; Electrons; Frequency measurement; Helium; Indium gallium arsenide; Indium phosphide; Resonance; VHF circuits; Velocity measurement;
Journal_Title :
Electron Devices, IEEE Transactions on
