A 24-GHz High-Isolation CMOS On–Off Keying Modulator With Reduced Input Impedance Variation

In this letter, a 24-GHz high-isolation ON-OFF keying (OOK) modulator with reduced input impedance variation in a 65-nm CMOS technology is proposed. A modified magnetic coupled triple-cascode configuration with a series inductor and two shunt transistors, which can simultaneously improve the ON/OFF isolation and reduce the input return loss variation between the ON- and OFF-states, is designed and analyzed for the first time. Based on this configuration, the OOK modulator achieves a 45.7-dB ON/OFF isolation and maintains better than 10-dB return loss for both the ON- and OFF-states. In addition, a data rate of 3.3 Gbps is achieved.