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Hole-initiated avalanche multiplication is investigated using an AlGaAs/InGaAs p-n-p heterojunction bipolar transistor (HBT). Both experimental measurements and theoretical calculation are used to determine the avalanche multiplication factor. A large departure is observed at low electric field when comparison is made between the measured data and theoretical results obtained from the standard ionization model. The comparison shows that the conventional impact ionization model, based on local electric field, substantially overestimates the hole avalanche multiplication factor M[sub p]-1 in the AlGaAs/InGaAs p-n-p HBT, where a significant dead space effect occurs in the collector space-charge region. A simple correction model for the dead space is proposed, that allows the multiplication to be accurately predicted, even in a heavily doped structure. Based on this model, multiplication characteristics for different threshold energy of the hole are calculated. A threshold energy of 2.5 eV was determined to be suitable for describing the hole-initiated impact ionization process. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

An InGaP/GaAs heterojunction bipolar transistor (HBT) power amplifier is developed for WCDMA user equipment, specifically, band-1-power class-2 application. The HBT power amplifier demonstrates maximum output power Pout of 29.4 dBm and power-added efficiency (PAE) of 48% at a frequency of 1.95 GHz. When operated according to the WCDMA standard, it achieves Pout of 27 dBm and PAE of 32.4%. The adjacent channel leakage power ratio (ACLR) is -33 dBc. A compact microstrip resonant cell (CMRC) circuit is implemented on the HBT amplifier in order to further improve the PAE, ACLR, and IM3 performances. This results in improvements of 8 dB and 6% for the ACLR and PAE, respectively. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 84–88, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20908 [ABSTRACT FROM AUTHOR]

Presents a study which investigated the temperature dependence of the current gain for GaAs-based heterostructure-emitter bipolar transistors. Theoretical analysis; Methods; Results and discussion; Conclusion.

The thermal stability of current gain in InGaP/GaAsSb/GaAs double-heterojunction bipolar transistors (DHBTs) is investigated. The experimental results show that the current gain in the InGaP/GaAsSb/GaAs DHBTs is nearly independent of the substrate temperature at collector current densities >10 A/cm2, indicating that the InGaP/GaAsSb/GaAs DHBTs have excellent thermal stability. This finding suggests that the InGaP/GaAsSb/GaAs DHBTs have larger emitter-base junction valence-band discontinuity than traditional GaAs-based HBTs. [ABSTRACT FROM AUTHOR]