摘要:

For discretionary channel routing problems, some but not all the pins in the channel are required to be connected by their respective nets. It is solved in two phases: a selection phase, in which a set of pins that must be connected for each net is identified, and a connection phase, in which selected pins are interconnected to their respective nets. A new selection phase algorithm based on a simple score function is proposed. Its overall performance on examples taken from previous literature is better than that of four existing techniques.

DOI:10.1049/ip-i-1.1988.0009

出版商:IEE    

年代:1988

数据来源: IET

摘要:

A large-signal field analysis of an O-type travelling-wave amplifier employing a practical focusing-field arrangement is presented, based on a coupled Eulerian-Lagrangian formulation of the problem. The resulting three-dimensional electron trajectories give rise to a beam that varies with the axial co-ordinate and time. It is shown that the boundary conditions on the moving (a prioriunknown) beam boundary can be automatically satisfied by redefining the charge and current densities for all values of the radial co-ordinate. The key step in the analysis is a representation of the field components as functions of the electron-arrival time and the electronradial position, through a sequence of Green's functionals for the slow-wave circuit. Substitution of this representation into the electron ballistic equations reduces the latter to a fixed-point problem for a pair of operators in an appropriate function space. The fixed point, and therefore the solution for the electromagnetic field components, can be obtained by standard successive approximation techniques. Finally, it is shown that when the radial component of the focusing magnetic field vanishes and its axial component becomes constant, the electron trajectories degenerate to straight lines parallel to the tube axis.

DOI:10.1049/ip-i-1.1988.0011

出版商:IEE    

年代:1988

数据来源: IET

摘要:

Optical annealing and zirconium diboride barrier layers have been optimised for Ni, Au, Ge alloyed ohmic contacts ton-GaAs. Contact resistances of below 0.06 Ωmm with a standard deviation of 0.02 Ωmm were attained across a 50 mm diameter wafer. MESFETs produced using this new technology have shown very good characteristics and minimal degradation after temperature stressing at 300°C for 100 h. Fully-functional yields of 32% were obtained for high speed MSI circuits with 15 mm gate width. The very stable and low contact resistance of these optically annealed zirconium diboride contacts combined with the high yield and good circuit performance demonstrate the suitability of these contacts for use in GaAs high-speed circuits.

DOI:10.1049/ip-i-1.1988.0012

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The turnon and turnoff transients of Schottky-barrier diode are determined by analysis based on thermionic emission across the metal-semiconductor barrier and a displacement current within the space charge region. The results of the analysis are compared to those from device simulator and are shown to be in excellent agreement. 10%; time constants for both turnon and turnoff transients are shown to be strongly controlled by the SBDs depletion capacitance reverse bias.

DOI:10.1049/ip-i-1.1988.0013

出版商:IEE    

年代:1988

数据来源: IET