A novel high-Q inductor based on Si 3D MMIC technology and its application

Abstract

A novel high-Q spiral inductor, implemented on a conductive Si wafer by applying the 3D MMlC structure over it, is proposed. The proposed inductor effectively uses a 1O-pthick polyimide layers and ground plane with a window below the spiral. A Q-factor of 21.7 at 1.88 nH and 5.8 GHz is achieved. A 5 GHz-band LNA is also designed with the new inductors and Si BJT with f , , , of 24 GHz, and the highest-class of performance was predicted with a 20 dB gain and a 2.5 dB noise figure.

Surface micromachined high-performance RF MEMS inductors

“…Since both types of inductors differ in the cores, the dielectric loss becomes the dominant source of the loss at high frequency. Many research papers were reported to reduce the loss by using a layer or multilayer of polyimide to improve the Q-factors of inductors [15][16][17][18][19].…”

MEMS for wireless communications: from RF-MEMS components to RF-MEMS-SiP

“…compared to Si and the use of gold interconnects which are slightly thicker and display a lower resistivity than the aluminum (alloy) interconnects. Introducing nonstandard materials and techniques such as gold, copper or thick (3-5 µm) aluminum, high-resistivity silicon substrates, copperdamascene interconnect technology, thick passivation layers beneath the inductor or special 3D designs consisting of stacked metal layers helps in pushing the Q-factor up to 20-30 for silicon-based technologies [7][8][9][10][11][12][13]. The use of MEMS technology is among the strategies employed to improve onchip inductor performance.…”

“…Inductor Qs for low cost (Bi)CMOS or bipolar technologies, used for application below 10 GHz, are typically limited to around 10 [5,6]. Special processing steps, introduced at the expense of higher processing complexity and cost, help in pushing the Qfactors up to 20-30 [7][8][9][10][11][12][13], still not high enough, however, for many important circuit functions in wireless communication systems. Inductor Qs of at least 30 are desired to design low-loss (less than a few dB) LC-type bandpass filters with a steep roll-off, to meet the stringent phase-noise specifications for VCOs, to improve power transfer matching in PAs and to reduce the noise figure in LNAs.…”