A CMOS LC‐tank frequency divider with 3D helical inductors

Abstract

AbstractThe design of a frequency divider (FD) employing 3D helical inductors fabricated in the 0.18‐μm 1P6M CMOS technology is reported. The LC resonators consist of two 3D helical inductors and varactors. The aim of using 3D inductor is to reduce chip size, the inductance of inductor is designed to be 2 nH, and the size of the inductor is 155 × 155 μm2. The divide‐by‐2 LC‐tank injection locked FD is performed by adding an injection nMOS between the differential outputs of the divider with the structure of cross‐coupled n‐core VCO that contains a tapped LC resonator. The measurement results show that at the supply voltage of 1 V, the divider free‐running frequency is tunable from 2.496 to 2.04 GHz, and at the incident power of 0 dBm the locking range is about 1.31 GHz (30%), from the incident frequency 3.84–5.12 GHz. The core power consumption is 2.59 mW. The die area is 0.664 × 0.731 mm2. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1477–1480, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22453