A fully integrated 10-Gb/s tapped delay Hilbert transformer for optical single sideband

A 10-Gb/s SiGe HBT tapped delay Hilbert transformer (HT) integrated circuit (IC) is described. The four tap filter uses an integrated LC transmission line with a total delay of 180ps, and the HT has a nominal group delay of 120ps. The circuit is fabricated in a 47-GHz f/sub T/ SiGe HBT process and consumes 112mW from a -3.3-V supply. Measured s-parameters and time domain waveforms are shown to agree with theory. Measurements of a 10-Gb/s optical single sideband system indicate that 7dB of broadband sideband suppression is obtainable using the IC.