The fabrication and characterization of an 11-stage ring oscillator utilizing integrated enhancement- and depletionmode (E/D-mode) high-electron mobility transistors (HEMT's) in the lattice-matched InAlAs/InGaAs/InGaAs material system is demonstrated. The 0.5-ìçé gate length depletion-mode HEMT's (D-HEMT's) used in the circuit exhibit a threshold voltage (VT) of -365 mV with a standard deviation of 19 mV, while the enhancement-mode HEMT's (E-HEMT's) with identical gate length display a VT of 195 mV with a standard deviation of only 9 mV. The unity current gain cutoff frequency (ft) for both devices is 70 GHz. The extremely high uniformity of the threshold voltages of these devices allowed for the implementation of a ring oscillator utilizing direct coupled FET logic (DCFL). At a supply voltage of 0.4 V, a room temperature propagation delay time (τpd) of 22.4 ps/stage, and a corresponding power dissipation of 120 μW/stage is measured, yielding a power delay product (PDP) of 2.65 fJ/stage. To the best of the authors' knowledge, this is the first demonstration of a circuit employing E/D-HEMT technology in the lattice-matched InP-based material system.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering