A transformer (100, 180, 500) is described. The transformer comprises a top conductive coil (106, 206, 506), a bottom conductive coil (102), and a dielectric layer (104, 504) separating the top conductive coil from the bottom conductive coil. The top conductive coil comprises an outermost portion (110, 510) having multiple segments (142, 144, 148). The segments are configured to reduce the peak electric field in a region of the dielectric layer near the outer edge of the top conductive coil. The top conductive coil may comprise a first lateral segment (142), and a second lateral segment (144) that is laterally offset with respect to the first lateral segment. The first lateral segment may be closer to the center of the top conductive coil than the second lateral segment, and may be closer to the bottom conductive coil than the second lateral segment. The transformer may be formed using microfabrication techniques.