Reducing inductive effects in radio frequency integrated circuits.

摘要

The continuous scaling of silicon CMOS technology has improved the performance of CMOS integrated circuits (ICs) enough to enable operation at radio frequencies (RF). Consequently, increasingly large portions of RFICs are being made in CMOS technology due to widespread availability and relatively low cost. Examples include wireless networks, GPS, cellular phones, and Bluetooth.;With the advent of silicon RFICs, circuit designers have been taking advantage of inductance to build many different RF circuit blocks from voltage-controlled oscillators (VCOs) to tuned amplifiers. Consequently, on-chip inductors have become key components in RF circuits and can be clearly seen on many chip layouts. However, the higher frequencies and higher levels of integration that accompany scaling begin to exacerbate some unwanted inductive effects. In particular, inductors in close proximity exhibit magnetic crosstalk that results in more interference, and interconnect shows more loss at higher operating frequencies. These effects are significant in modern communication circuits where interference or loss in signal power directly hampers circuit operation.;This work investigates techniques to reduce these unwanted inductive effects in an IC environment. A new inductor structure, the quadrupole inductor, results in less crosstalk and is used in a VCO to demonstrate improved isolation from neighboring interferers. Also, a slotted ground shields are used in conjunction with coplanar waveguides (CPWs) to create low-loss interconnect. Results from this research show that the quadrupole inductor can reduce crosstalk by 30 dB and CPWs with slotted ground shields exhibit a low loss of -0.42 dB/mm at 45 GHz.