A 2.7-V dual-frequency single-sideband mixer [for PCS]

The single-sideband (SSB) mixer is attractive since it can provide either upper or lower sideband output through an electronic control. However, it is essential for the dual-band SSB mixer to achieve high sideband rejections in both frequency bands. The sideband rejection depends on the system specifications and actual off-chip filters used in the handset, and is typically -35 dB or lower. This paper describes the design of a 0.8/2-GHz BiCMOS dual-frequency single-sideband mixer. A phase tracking technique is employed to combat the inaccuracy of quadrature shifters due IC process variations and to achieve high sideband rejections (<-35 dB) for both frequencies.