  We demonstrate a photonic RF integrator based on an integrated soliton
crystal microcomb source. By multicasting and progressively delaying the input
RF signal using a transversal structure, the input RF signal is integrated
discretely. Up to 81 wavelengths are provided by the microcomb source, which
enable a large integration time window of 6.8 ns, together with a time
resolution as fast as 84 ps. We perform signal integration of a diverse range
of input RF signals including Gaussian pulses with varying time widths, dual
pulses with varying time intervals and a square waveform. The experimental
results show good agreement with theory. These results verify our
microcomb-based integrator as a competitive approach for RF signal integration
with high performance and potentially lower cost and footprint.
