We present a novel nonlinear transmission line (NLTL) pulse generator using dual-NLTL, true-time-delay, waveform-alignment technique, realized in Gallium Arsenide (GaAs) monolithic microwave integrated circuit (MMIC) technology. The diodes in these two NLTLs have opposite polarities in layout. Therefore, they are responsible for sharpening the two signals' rising and falling edges separately. A simple, low-cost, wideband combiner is adopted to combine the two fine aligned waveforms without introducing much distortion to the wideband signal. As a result, a sharp pulse is obtained with both edges compressed. With a sinusoidal signal as the input to the fabricated MMIC, a fall time of around 12 ps and rise time of 14 ps were measured at the output. This MMIC is a candidate for pulse or comb generators in many commercial and military applications.

No abstract

The hole multiplication factor in pnp InAlAs/InGaAs single heterojunction bipolar transistors (HBTs) has been measured as a function of the base-collector bias. The hole impact ionization coefficient beta (p) has been estimated taking into account the Early effect, I-CBO, and thermal effects. Numerical corrections for dead space were made. The importance of considering second order effects is highlighted, showing that rough approximations can lead to an overestimation of the coefficient beta (p). At low electric fields, the extracted coefficient agrees with the most recent photomultiplication measurements available in the literature, At high electric fields, hole impact ionization coefficient is estimated up to values previously not reported in the literature (beta (p) approximate to 10(4) cm(-1))

No abstract

No abstract