Modeling and Characterization of Sub-nanosecond Impulse Response of High-Voltage Heterojunction Bipolar Transistors

Sub-nanosecond impulse response of high-voltage InGaAs/GaAs HBTs was characterized by using a time-domain sampling oscilloscope with the cable delay and loss corrected in frequency domain. A peak voltage of 10 V with a width of 200 ps was obtained, which was attributed to the delayed onset of the Kirk effect. The Agilent HBT model was modified to account for the stronger-than-expected field and temperature dependence of the Kirk effect. The modified model correctly predicts the impulse response of the HBT and, hence, can be used in the design and simulation of impulse-based ultra-wideband circuits.