  We demonstrate a photonic RF Hilbert transformer for broadband microwave
in-phase and quadrature-phase generation based on an integrated frequency
optical comb, generated using a nonlinear microring resonator based on a CMOS
compatible, high-index contrast, doped-silica glass platform. The high quality
and large frequency spacing of the comb enables filters with up to 20 taps,
allowing us to demonstrate a quadrature filter with more than a 5-octave (3 dB)
bandwidth and an almost uniform phase response.
