Resistor string with equal resistance resistors and converter

Abstract

An integrated circuit includes a string of substantially similarly-shaped resistive cells, each cell having a first resistive portion and a second resistive portion, the string having an overall orientation and at least one cell, preferably substantially all cells, and more preferably all cells have their respective centerlines oriented at non-orthogonal angles, preferably about 45 degrees, relative to the overall orientation. The cells are contiguous such that a resistor is formed by the first resistive portion of one cell and the second resistive portion of an adjacent cell. The cells preferably have a substantially hexagonal shape and are arranged into substrings. If the string includes a folding point, substrings immediately adjacent to the folding point should include an odd number, preferably three, of cells, and substrings not adjacent to the folding point should comprise an even number, preferably two, of cells. Preferably, the hexagonally shaped cells include two longer sides and four shorter sides, each cell having a tap substantially centrally positioned along one of its longer sides, a resistor being formed between the taps of any two adjacent cells. The taps are preferably arranged to form a grid such that each tap is aligned with at least one other tap substantially parallel to the overall orientation and each tap is aligned with at least one other tap substantially perpendicular to the overall orientation. A converter, such as a digital-to-analog converter (DAC) or an analog-to-digital converter (ADC) includes such a resistor string.