| Summary: | A 24-GHz direct-conversion transmitter is proposed for in-cabin radar applications. The proposed RF transmitter consists of an <i>I</i>/<i>Q</i> up-conversion mixer, an <i>I</i>/<i>Q</i> local (LO) oscillator generator, and a power amplifier. To improve the linearity of the <i>I</i>/<i>Q</i> up-conversion mixer, an inverter transconductor with third-order intermodulation (IM3) distortion cancellation is proposed. To improve the <i>I</i>/<i>Q</i> balancing performance of the <i>I</i>/<i>Q</i> LO generator, a poly-phase filter, including parasitic line inductance, is proposed. By employing a highly linear <i>I</i>/<i>Q</i> up-conversion mixer and a balanced <i>I</i>/<i>Q</i> LO generator, the 24-GHz direct-conversion transmitter achieves high linearity and <i>I</i>/<i>Q</i> balancing characteristics. It is fabricated in a 65-nm CMOS process and consumes 150 mW. It shows an OP1dB of 8.6 dBm, an LO leakage of −48 dBc, and an image rejection ratio of −49 dBc for the entire operating band from 24 GHz to 24.5 GHz.
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