Title :
Unilateral power gain limitations due to dynamic base widening effects
Author :
Willén, B. ; Rohner, M. ; Jäckel, H.
Author_Institution :
Dept. of Electron., R. Inst. of Technol., Kista, Sweden
Abstract :
It is shown that the maximum frequency of oscillation of an InP-HBT may be limited by the low velocity of the holes when operated in the base push-out regime since modulation of the extended base will be delayed by the hole transit time, having an effect also on the electron current. The resulting delay of the current response causes a peaking of the unilateral power gain followed by a -40 dB/decade roll-off, being a source for a strong overestimation of the extrapolated cut-off frequency when neglected. An extended equivalent small-signal circuit is proposed that takes these effects into account.
Keywords :
III-V semiconductors; equivalent circuits; heterojunction bipolar transistors; hole mobility; indium compounds; semiconductor device models; InP; InP HBT; base push-out; current response delay; cut-off frequency; dynamic base widening; electron current; equivalent circuit; hole transit time; hole velocity; maximum frequency of oscillation; roll-off; small-signal model; unilateral power gain; Charge carrier processes; Charge carriers; Circuits; Current density; Cutoff frequency; Delay effects; Doping; Heterojunction bipolar transistors; Indium phosphide; Phase modulation;
Journal_Title :
Electron Device Letters, IEEE
