Showing papers by "Bobby Brar published in 2007"
14 May 2007
TL;DR: In this paper, a 30-nm enhancement-mode (E-mode) InGaAs/InAlAs high electron mobility transistors (HEMTs) with an extremely high transconductance (gm) of 2.22 S/mm, a current gain cutoff frequency (fT) of 554 GHz, and a maximum oscillation frequency (mfmax ) of 358 GHz were successfully developed.
Abstract: We have successfully developed 30-nm enhancement-mode (E-mode) InGaAs/InAlAs high electron mobility transistors (HEMTs) with an extremely high transconductance (gm ) of 2.22 S/mm, a current gain cutoff frequency (fT) of 554 GHz, and a maximum oscillation frequency (fmax ) of 358 GHz. The excellent high-speed performance was obtained by using a Pt/Mo/ Ti/Pt/Au buried gate technology, which enabled E-mode operation for very short 30-nm HEMTs while maintaining a low access resistance as well as a low gate leakage current. The effectively short gate-to-channel distance suppressed the short channel effect, resulting in a very high gm independent of the gate length (Lg ) and a greatly reduced output conductance (gd).
17 citations
03 Jun 2007
TL;DR: An indium-phosphide (InP) double-heterojunction bipolar transistor (DHBT) process for compact millimeter-wave power amplifier MMICs has been developed with integrated 15 mum thick layers of BCB dielectric as discussed by the authors.
Abstract: An indium-phosphide (InP) double-heterojunction bipolar transistor (DHBT) process for compact millimeter-wave power amplifier MMICs has been developed with integrated 15 mum thick layers of BCB dielectric. The thick BCB layers provide low-loss millimeter-wave transmission lines with much smaller dimensions compared to conventional microstrip placed directly on the semiconductor substrate. A single layer BCB process with two metal layers is used for microstrip circuits, and a two-layer BCB process (30 mum total thickness) with three metal layers is used for stripline MMICs. The stripline MMICs inherent shielding enables new MMIC packaging concepts such as three dimensional embedded circuits that are enabling for low-cost phased array antennas architectures. A two-stage cascode power amplifier has been fabricated and characterized using microstrip lines on a single thick layer of BCB. The compact 6 mm2 Ka-band PA demonstrated 1.1 Watts of saturated output power at 38 GHz, a dc power added efficiency (PAE) was 28.6%, and a small signal gain of 14.9 dB. The measured die area power density is 18.3 W/cm2. These results demonstrate the potential of thick BCB microstrip and stripline MMICs to enable compact power amplifiers for space constrained millimeter-wave applications.
14 citations
19 Nov 2007
TL;DR: In this paper, an ultra-wideband ultra-low-DC power high gain MMIC low noise amplifier (LNA) with differential RF input using 0.1mum gate length InAs/AlSb metamorphic HEMTs, fabricated and characterized on a GaAs substrate.
Abstract: This paper reports an ultra-wideband ultra-low-DC power high gain MMIC low noise amplifier (LNA) with differential RF input using 0.1-mum gate length InAs/AlSb metamorphic HEMTs, fabricated and characterized on a GaAs substrate. For testing purpose and for generating a differential RF input, a 3-12 GHz wideband on-chip MMIC balun is connected to the differential input. Even with the loss of the balun included, the differential amplifier demonstrated 4 dB typical noise figure with associated gain of 22 dB from 3-12 GHz at a low DC dissipation of 23 mW. Additionally, a single-ended LNA, which the differential LNA is based on, is also fabricated for evaluation. The single-ended LNA demonstrated 1.5 dB typical noise figure with associated gain of 25 dB from 1-16 GHz at a low DC dissipation of 16 mW
9 citations