A microwave (MW) synthesizer is a key component of high-performance coherent population trapping (CPT) atomic clocks, which are competitive candidates as miniature, low-power-consumption atomic clocks. In this work, we demonstrated a microwave synthesizer and a self-adaption system to satisfy the requirement of short term and mid-long term frequency stability of CPT clocks. From the experimental results, the absolute phase noise of the microwave synthesizer was measured as −110 dBc/Hz at 200 Hz. The off-resonant light shift limitation for CPT clock can achieve better than $2 \times10^{-14}$ based on our microwave synthesizer and self-adaption system. The proposed low-phase-noise microwave synthesizer and self-adaption system presented can also be used in other high-performance microwave atomic sensors and standards.
