An octal amplitude shift keying (ASK) modulation circuit working at 10 GHz was designed in a 0.18 μm CMOS process. By using the structural characteristics of distributed amplifier, a set of switches were added to change the signal transmission path and control the amplitude and phase of the output signal, and the octal amplitude shift keying modulation of the signal was realized, which effectively improved the frequency band utilization of the signal transmission. The simulation results showed that the data rate of the modulation circuit could reach 3 Gbit/s with the carrier frequency of 10 GHz, and the energy consumption per bit was 12 pJ. The average power consumption was 36.35 mW.