George I. Haddad

Learn More
Many semiconductor quantum devices utilize a novel tunneling transport mechanism that allows picosecond device switching speeds. The negative differential resistance characteristic of these devices, achieved due to resonant tunneling, is also ideally suited for the design of highly compact, self-latching logic circuits. As a result, quantum device(More)
The resonant tunneling diode (RTD) has been widely studied because of its importance in the field of nanoelectronic science and technology and its potential applications in very high speed/functionality devices and circuits. Even though much progress has been made in this regard, additional work is needed to realize the full potential of RTD's. As research(More)
First augmented circuit simulator version was named NDR SPICE (1994) and was added with simple mechanisms like forced convergence routine to recover from oscillatory (non-convergence) situations in DC simulation. The second version, named QSPICE (1999), was augmented with homotopy-based convergence routine, named RTD-stepping as well as a novel limiting(More)
Devices from three major groups of two-terminal devices, i.e., transit-time diodes, transferred-electron devices, and quantum-well devices, have been employed successfully to generate RF power at frequencies above 200 GHz. At frequencies up to 300 GHz, Si IMPATT diodes yielded the highest RF power levels from any fundamental solid-state source, e.g., 50 mW(More)
An ultrafast 32-bit pipelined correlator has been implemented using resonant tunneling diodes (RTDs) and hetero-juncfion bipolar transistors (HBTs). The negative differential resistance (NDR) characteristics of RTDs is the basis of logic gates with the self-latching property that eliminate pipeline area and delay overheads which limit throughput in(More)
23 mm antenna), the two field components become comparable. For a 21 ϫ 21 mm antenna with the proposed type of slot, we found that the antenna generates left-hand circular polarization [9]. The 3-dB axial-ratio bandwidth obtained was 2.8%. The impedance bandwidth is much wider. Note that if the slots are reversed, right-hand circular polarization results(More)
transmission line can be achieved by varying the size of the centre conductor [15]; here, the size of the outer conductor is fixed. The centre conductor of the resulting suspended coaxial transmission line is shown in Figure 2(a), with the cross-sections of the 50⍀ line and the stubs shown in Figure 2(b). The input and output of the suspended transmission(More)
The feasibility and potential of laser sources based on intersubband transitions in quantum wells and strained layers will be presented. The basic schemes and proposed structures for both electrically and optically pumped devices are discussed. Both conduction band and valence band quantum wells as well as strained layers may be used as the active layer of(More)
Resonant tunneling diodes (RTDs) have intriguing properties which make them a primary nanoelectronic device for both analog and digital applications. We propose a bistable RTD-based cell for the cellular neural network (CNN) which exhibits superior performance in terms of circuit complexity, and processing speed compared to standard cells.
  • 1