  The potential of frequency comb spectroscopy has aroused great interest in
generating mid-infrared frequency combs in the integrated photonic setting.
However, despite remarkable progress in microresonators and quantum cascade
lasers, the availability of suitable mid-IR comb sources remains scarce. Here,
we present a new approach for the generation of mid-IR microcombs through
cascaded three-wave-mixing. By pumping a CdSiP$_2$ microresonator at 1.55
$\mu$m wavelength with a low power continuous wave laser, we generate
$\chi^{(2)}$ frequency combs at 3.1 $\mu$m wavelength, with a span of about 30
nm. We observe ordinary combs states with a line spacing of the free spectral
range of the resonator, and combs where the sideband numbers around the pump
and half-harmonic alternate, forming staggered patterns of spectral lines. Our
scheme for mid-IR microcomb generation is compatible with integrated telecom
lasers. Therefore, it has the potential to be used as a simple and fully
integrated mid-IR comb source, relying on only one single material.
