A CMOS auto-calibrated I/Q generator for Sub-GHz ultra low-power transceivers

An ultra low-power 0.3-1 GHz auto-calibrated in-phase/quadrature generator has been designed and fabricated in a 90-nm CMOS technology. The circuit generates quadrature signals by means of master-slave dividers and the calibration is performed by using a delay-locked loop. The phase correction technique is embedded in the dividers and in the limiting amplifiers and is based on resistively-tunable circuits. The phase error is lower than 3.5 degrees with respect to process tolerances and is low-sensitive to temperature and supply variations. The phase error can be greatly attenuated by tuning the reference voltage of the delay-locked loop through a digital word. This results in a phase error lower than 1 degree with frequency, temperature, and supply variations. The circuit current consumption is 0.5 mA from a 1.2-V supply.