A CMOS multiphase shifting network with RC-CR filter and bias-level-scaled active interpolator

A CMOS multiphase shifting network is described, which is developed for the use in a subharmonic mixing based direct-conversion receiver of 5–6 GHz wireless LAN. Accurate phase shift and amplitude matching are simultaneously achieved with a third-order RC–CR filter followed by the active interpolators whose bias levels are scaled for accurate phase shift. Implemented in a 0.18 μm CMOS process, the phase shifting network provides octa-phase local oscillator (LO) signals spaced by 45°. The measured accuracy of the phase shift and amplitude matching are better than 0.8° and 0.4%, respectively. The phase shifting network excluding LO buffers dissipates 13 mW from a 1.8 V supply voltage. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 118–121, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22033