Table lookup method based on grid and kd-tree composite structure

Abstract

The invention belongs to the field of integrated circuits and relates to a table lookup method based on a grid and kd-tree composite structure. The table lookup method includes firstly uniformly dividing grids on a definition domain plane, positioning coordinate points to be solved in some grids, constructing a data structure of the kd-tree at the grid positions, further subdividing the definition domain plane, positioning the plane in a more accurate coordinate range, and finally functional values of the coordinate points to be solved by the bilinear interpolation method. The table lookup method has faster lookup and positioning speed, the obtained result is more accurate, and tests indicated that a table lookup model with the composite structure can obtain more accurate result than that with a single structure and is shorter in lookup computing time. The table lookup method has higher application value in the small signal analysis and simulation stage of a simulation circuit.

Description

technical field [0001] The method belongs to the field of integrated circuits, and specifically relates to a table search method based on a mixed structure of a grid and a multidimensional tree. Background technique [0002] With the rapid development of integrated circuit technology, the operating frequency of integrated circuits has reached several GHz, the number of monolithic integrated circuit transistors has reached hundreds of millions, and the feature size has entered 22 nanometers [1]; When the simulation scale becomes larger, therefore, higher requirements are put forward for the simulation speed and memory overhead. [0003] In the traditional transistor circuit simulation process, the actual transistor current value is the result of calculating the response of the port voltage value, and after many iterations of convergence, while for the real-time circuit simulation system, the process of applying excitation and measuring the port response is too Time-consuming...

AI Technical Summary

Problems solved by technology

[0004] The table lookup model is currently a brand-new method for circuit simulation modeling. The earliest table lookup model is used in the fast timing simulation tool MOTIS for digital circuits [3-4], by storing a three-dimensional table to store the value of the port voltage , use linear interpolation method to solve I d [5-6], for the rough simulation of digital circuits, this method can provide acceptable simulation accuracy, but for the small signal simulation of analog circuits, because it needs to ensure the accuracy of a large number of parameters, the memory required by the table lookup method is greatly increase, and linear interpolation will lead to discontinuous results when differential [7], so the table lookup method has a lot of room for improvement. At present, the most considered is to reduce the I d Dependence with three variables, that is, reduce the dimension of the three-dimensional table to two-dimensional under the premise of ensuring accuracy

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