  Microwave photonics (MWP), harnessing the tremendous bandwidth of light to
generate, process and measure wideband microwave signals, are poised to spark a
new revolution for the information and communication fields. Within the past
decade, new opportunity for MWP has emerged driven by the advances of
integrated photonics. However, despite significant progress made in terms of
integration level, a fully on-chip MWP functional system comprising all the
necessary photonic and electronic components, is yet to be demonstrated. Here,
we break the status quo and provide a complete on-chip solution for MWP system,
by exploiting hybrid integration of indium phosphide, silicon photonics and
complementary metal-oxide-semiconductor (CMOS) electronics platforms. Applying
this hybrid integration methodology, a fully chip-based MWP microwave
instantaneous frequency measurement (IFM) system is experimentally
demonstrated. The unprecedented integration level brings great promotion to the
compactness, reliability, and performances of the overall MWP IFM system,
including a wide frequency measurement range (2-34 GHz), ultralow estimation
errors (10.85 MHz) and a fast response speed (0.3 ns). Furthermore, we deploy
the chip-scale MWP IFM system into realistic application tasks, where diverse
microwave signals with rapid-varying frequencies at X-band (8-12 GHz) are
accurately identified in real-time. This demonstration marks a milestone for
the development of integrated MWP, by providing the technology basis for the
miniaturization and massive implementations of various MWP functional systems.
