A semiconductor structure, comprising: a semiconductor substrate; a well region on the semiconductor substrate, having a first conductive type; a radio frequency circuit, comprising at least one FIN field-effect transistor having a plurality of first fins and a plurality of first polys on the well region, wherein the first polys are perpendicular to the first fins; a pair of guard rings (320, 330) disposed on respective sides of the RF circuit adjacent to the RF circuit, wherein each of the guard rings comprises a plurality of second fins (360, 370) and a pair of second polys (325, 335) on the well region, wherein the second fins (360, 370) have the first conductive type, wherein the second polys (325, 335) are perpendicular to the second fins (360, 370); a first isolation region on the well region directly disposed between the RF circuit and the first guard ring, a second isolation region on the well region, wherein the second isolation region is directly disposed between the RF circuit and the other guard ring; a first dummy poly arranged between the RF circuit and the first guard ring on the first isolation region; and a second dummy poly arranged between the RF circuit and the other guard ring on the second isolation region; wherein the first and second dummy polys (340A, 340B) are arranged parallel to the first and second polys (325, 335); wherein the first and second dummy polys (340A, 340B) overlap the first and second isolation regions, respectively; wherein the first fins are arranged parallel to the second fins (360, 370), and wherein the first fins are separated from the second fins (360, 370) by the first and second isolation regions. a semiconductor substrate; a well region on the semiconductor substrate, having a first conductive type; a radio frequency circuit, comprising at least one FIN field-effect transistor having a plurality of first fins and a plurality of first polys on the well region, wherein the first polys are perpendicular to the first fins; a pair of guard rings (320, 330) disposed on respective sides of the RF circuit adjacent to the RF circuit, wherein each of the guard rings comprises a plurality of second fins (360, 370) and a pair of second polys (325, 335) on the well region, wherein the second fins (360, 370) have the first conductive type, wherein the second polys (325, 335) are perpendicular to the second fins (360, 370); a first isolation region on the well region directly disposed between the RF circuit and the first guard ring, a second isolation region on the well region, wherein the second isolation region is directly disposed between the RF circuit and the other guard ring; a first dummy poly arranged between the RF circuit and the first guard ring on the first isolation region; and a second dummy poly arranged between the RF circuit and the other guard ring on the second isolation region; wherein the first and second dummy polys (340A, 340B) are arranged parallel to the first and second polys (325, 335); wherein the first and second dummy polys (340A, 340B) overlap the first and second isolation regions, respectively; wherein the first fins are arranged parallel to the second fins (360, 370), and wherein the first fins are separated from the second fins (360, 370) by the first and second isolation regions.