1. Field of the Invention
The invention relates to the design and manufacture of an electronic circuit, and more particularly to a method for producing a semiconductor device using a logic simulation approach to simulate a multi-peak resonant tunneling diode (RTD)-based electronic circuit and a large signal multi-peak RTD SPICE model employed in the logic simulation approach.
2. Description of the Related Art
Currently, research in the use of resonant tunneling diodes (RTD) in electronic circuits, such as frequency multipliers, analog-to-digital converters and multi-valued memories (MVM), is becoming more intense. Circuit simulators are usually employed in the design and manufacture of RTD-based electronic circuits in view of the great expense that would be incurred if an actual physical prototype of the electronic circuit is needed before one can determine if the electronic circuit would operate in the intended manner. SPICE is an example of a circuit simulation program used to predict the operation of a circuit design. SPICE simulates a circuit model by employing equations which attempt to define mathematically the operation of the various circuit components in the circuit design, and provides output signal information as a result of the simulation.
Presently, there are two available RTD models for SPICE. The first is an RTD switch model described in a publication by T. H. Kuo and H. C. Lin entitled "Large-signal Resonant Tunneling Diode for SPICE3 Simulation," IEDM Tech. Dig., 1989, pp. 567-570. The second is described in a publication by Z. X. Yan and M. J. Deen entitled "A New Resonant-Tunnel Diode-Based Multi-valued Circuit Using a MESFET Depletion Load," IEEE J. Solid-State Circuits, 1992, SC-27, (8), pp. 1198-1202.
The RTD switch model described in the first publication has a relatively complicated construction that becomes more and more complex as the number of peaks in the current-voltage characteristic curve of the RTD increases. This makes it inconvenient to provide circuit information to a computer loaded with the SPICE3 circuit simulation program, and may result in convergence problems during simulation.
In the second publication, a single-peak RTD is modeled by a parasitic resistance in series with the parallel combination of a voltage-controlled current source and an intrinsic capacitance. The voltage-controlled current source is implemented in SPICE using the look-up table's statement, which contains RTD measured characterizing data. A multi-peak RTD, however, is modeled as a series combination of at least two single-peak RTDs, thereby resulting in a complicated model that makes it difficult to input circuit information to a computer loaded with the SPICE program. Furthermore, convergence problems may also occur during simulation due to the complexity of the multi-peak RTD model that is in use. In addition, the look-up table's statement, which is a built-in feature of SPICE, does not accurately define the operation of a multi-peak RTD.