Fig. (15) (a) Vertical Hall-effect device with three contacts and single mirror symmetry in the z-plane. (b) The same device in the normalized q-plane. (c) Its conformal transformation on the upper half of the t-plane. (d) Its final transformation on the lower half of the w' -plane: there it is rotated by 180° to Fig. (4b) for W_a' = W₄' = k₂₃ and W_c' = W₆' = k₁₂ .