Power gain singularities in transferred-substrate InAlAs-InGaAs-HBTs

Abstract

Deep submicron transferred-substrate heterojunction bipolar transistors exhibit peaking and singularities in the unilateral power gain () at high frequencies. Unbounded has been observed in some devices over a 20-110 GHz bandwidth. Associated with the effect are a strong decrease in collector-base capacitance with increased bias current, and negative conductance in the common-emitter output conductance 22 and positive conductance in the reverse conductance 12. Unbounded is observed in devices operating at current densities as low as 0.56 mA m 2. A potential explanation of the observed characteristics is dynamic electron velocity modulation in the collector-base junction. A theoretical model for the dynamics of capacitance cancellation by electron velocity modulation is developed, and its correlation with experimental data examined.

G-band (140-220-GHz) InP-based HBT amplifiers

“…These effects may not be observed in a standard III-V mesa-HBTs because the reverse transmission characteristics are dominated by the large extrinsic collector-base capacitance. A more detailed discussion of these results will be presented elsewhere [13].…”