A circuit technique improving the image rejection of RF front-ends

This work presents a technique to reduce the phase errors of quadrature signals. The proposed concept is demonstrated on a 2.4-GHz single-sideband up-converter in a 0.35-/spl mu/m BiCMOS process. The quadrature LO signals are obtained on-chip by means of two coupled oscillators, achieving a figure-of-merit of 186 dB. The image-rejection ratio improves by 7 to 11dB across the 28% LO tuning range with respect to a conventional design. The whole circuit dissipates 47 mW.