Ratioed capacitances in integrated circuits
AssigneeU.S. Philips Corporation
InventorKenneth W. Moulding
Life of this patent
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Abstract
In an integrated circuit in which the capacitances of a pair of capacitors are arranged to be in a ratio k by choosing the areas of corresponding plates of the two capacitors to be in this ratio, and the plates are shaped so that the total lengths of their boundaries are also in this ratio so as to reduce the sensitivity of k to manufacturing tolerances, this sensitivity is further reduced by arranging that the ratios between the numbers of 90.degree. corners exhibited by the respective plates, and the numbers of 270.degree. corners exhibited by the respective plates, are each also substantially equal to k. To make this possible an aperture is arranged to be present in each plate.
Claims8
An integrated circuit including a first capacitor and a second capacitor, the first capacitor comprising a first continuous plate, a second continuous plate and a first layer of dielectric material of a given composition and thickness for spacing apart the first and second plates, the first continuous plate having an area defined by a boundary, the second capacitor comprising a third continuous plate, a fourth continuous plate and a second layer of dielectric material having a composition and thickness equal to those of the first layer and spacing apart the third and fourth plates, the first continuous plate having an area k times greater than the area of the third plate defined by a boundary which is k times longer than the boundary of the third plate where k is greater than unity, wherein the first plate is provided with an aperture defining a portion of the boundary, and the boundary of that plate comprises convex portions subtending a summation of internal angles and concave portions subtending a summation of external angles which is equal to the summation of internal angles, the third plate is provided with an aperture defining a portion of the boundary, and the boundary of that plate comprises convex portions subtending a summation of internal angles and concave portions subtending a summation of external angles which is equal to the summation of internal angles, and wherein the summation of internal angles and the summation of external angles of the first plate are substantially k times the summation of internal angles and the summation of external angles of the third plate.
Dependencies are inferred from the claim text.