I. Introduction
The growing interest in millimeter-wave transceivers for consumer, radar, and imaging applications has motivated work on various CMOS building blocks operating at 60 GHz and beyond [1]–[5]. the maximum speed of such circuits is typically limited by the quality factor, Q, of inductors or transmission lines: a higher Q would permit the use of a smaller inductance to resonate with transistor capacitances, thus achieving a higher speed. This limitation proves serious as skin effect and substrate loss in CMOS technology prohibit linear scaling of the Q with frequency, leading to values that tend to saturate for frequencies above 60 GHz. for example, [6] reports a Q of 12 for 180-pH inductors at 60 GHz, and [7] a Q of 17 for 400-pH inductors at 50 GHz.