A 24.25–29.5-GHz Transmitter with Built-in Automatic Calibration of LO Feedthrough and I/Q Imbalance in 65-nm CMOS

Due to the vast spectra and low latency, millimeter-wave 5 G wireless communication networks have become highly attractive. The 24.25-$29.5-\mathrm{GHz}$ band has been allocated as one of the 5 G new radio (NR) frequency range 2 (FR2) operating bands (i.e., n257, n258, n261). To achieve low error vector magnitude (EVM) in these bands, it is crucial to mitigate local oscillator feedthrough (LOFT) and I/Q imbalance. Compared with traditional methods, built-in automatic calibration for LOFT suppression and image rejection offers significant advantages for fast mass production.