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This paper describes a re-useable circuit module for a 90° phase shifter, sometimes called a "Hilbert transformer", which has been demonstrated on a 0.35-micron CMOS process. The 10-pole circuit is entirely analogue in operation, and achieves measured amplitude and phase accuracy compatible with >50 dB sideband suppression. Statistical design techniques assure good functional yields. Total current consumption is 236 microamps at 3.3 V, and chip area is 1.42 square mm, excluding bond pads. Applications include low power, low cost SSB receivers, more advanced communications architectures in GSM, DCS and G3, and sonar.