An E-band CMOS Direct Conversion IQ Transmitter for Radar and Communication Applications

This paper presents an E-band direct conversion IQ transmitter (TX) with IQ calibration for joint radar-communications system. To generate high-quality digitally modulated signal and frequency-modulated continuous-wave (FMCW) radar chirp signal, I/Q calibration capability is integrated in the TX with a miniaturized hybrid coupler and variable capacitors. The measured image rejection ratio and LO feedthrough suppression, which are critical for both communication and FMCW signal generation, are better than 36 and 23 dB, respectively, in the range of 74–83 GHz. The TX successfully generates not only a 24-Gb/s 16-QAM modulated signal but also a FMCW modulated signal with 1 GHz bandwidth. Moreover, as the LO frequency is tuned from around 74 GHz to 83 GHz, 16-QAM with EVM around −22 dB is measured. The output P1dB and conversion gain of the TX are 9.8 dBm and 12 dB, respectively.