PLANAR COIL AND PLANAR TRANSFORMER

摘要

A coil is so disposed as to minimize the loss in a restricted space. A planar coil is provided with a disc-shaped insulating layer (10) and N (N is an integer of 2 or more) turns of wiring (11) formed by arranging a planar conductor helically on one face of the insulating layer (10). The planar coil is characterized in that the radius ri(n) of the inner portion of the wiring (11) of the n-th turn (n is an integer of 1 to N) from the central part and the radius ro(n) of the outer portion are so determined that value (A) expressed by the Formula (1) takes on the minimum, when values rmin, D and Wtotal satisfy ri(1) = rmin, ri(n+1) - ro(n) = D and ro(N) - ri(1) = Wtotal. A = SIGMA <N>n-1{log(ro(n)/ri(n))}<-1> - - - (1).