A 28-GHz High Linearity Up-Conversion Mixer Using Second-Harmonic Injection Technique in 28-nm CMOS Technology

A 28-GHz high linearity active up-conversion mixer using 28-nm CMOS is presented in this letter. To enhance the modulated output power level under high-order modulation with IM3 improvement in the high IF input power region, the second-order intermodulation (IM2) signal injection technique is adopted. The positive third-order intermodulation (IM3) signal is generated by mixing the IM2 signal and IF input signal with transistors in the transconductance stage biasing in triode region. Therefore, by combining these opposite IM3 signal at the output of transconductance stage, the IM3 distortion can be alleviated. Besides, the proposed mixer achieves an IM3 distortion improvement in a wide IF power range. The measurement results demonstrate conversion gain (CG) of -6.4 dB and output 1-dB compression point (OP1 dB) of -2.2 dBm with 19 mW. The two-tone measurement results exhibit 10.2 dBm output third-order intercept point (OIP3). Furthermore, with the modulation measured results using single-carrier 256-QAM signal, the proposed mixer also exhibits a distinguished output power enhancement when the linearizer turns on. To the best of the author's knowledge, this design is the first demonstration and implemented of an IM2 signal injection technique in millimeter-wave frequency, which also improves the output power level of the high-order modulation measurement.