A CMOS 4-Element Ku-Band Phased-Array Transceiver

This paper presents a Ku-Band fully differential 4-element phased-array transceiver using a standard 180-nm CMOS process. Each transceiver is integrated with a 5-bit phase shifter and 4-bit attenuator for high-resolution radiation manipulation. The front-end system adopts time-division mode, and hence two low-loss T/R switches are included in each channel. At room temperature, the measured root-mean-square (RMS) phase error is less than 5.5°. Furthermore, the temperature influence on passive switched phase shifters is analyzed. Meanwhile, an extra phase-shifting cell is developed to calibrate phase error varying with the operating temperatures. With the calibration, the RMS phase error is reduced by 7° at −45 ℃, and 5.4° at 85 ℃. The RMS amplitude error is less than 0.92 dB at 15−18 GHz. In the RX mode, the tested gain is 9.6±1.1 dB at 16.5 GHz with a noise figure of 10.9 dB, and the input P_1dB is −15 dBm, while the single-channel’s gain and output P_1dB in the TX mode are 11.3±0.4 dB and 9.4 dBm at 16.1 GHz, respectively. The whole chip occupies an area of 5×4.2 mm² and the measured isolation between each two adjacent channels is lower than −23.1 dB.