A 24-30 GHz Balanced PA With High Linearity for mm-Wave 5G in 130 nm SiGe BiCMOS

In this paper, a balanced power amplifier (PA) which was fabricated in a 130 nm SiGe BiCMOS technology is presented for millimeter-wave (mm-wave) fifth generation (5G) application. In the phase array systems, the impedance of the antenna varies as the beam scans, which deteriorates the performance of the PA, especially the linearity. The proposed balanced PA with excellent input and output return losses, high gain, and high linearity owns load-variation insensitivity. The output powers of the PA with different loads are analyzed in detail. A quadrature coupler is designed in a spiral shape with a compact area and low insertion loss for the balanced PA. On-wafer measurements show a measured small-signal gain of 25.9 dB in 24–30 GHz with a 3-dB bandwidth of 18 GHz (15.5-33.5 GHz). The measured OP
1dB
and Psat are 19.62 and 21.56 dBm, respectively, with the peak power added efficiency (PAE) of 15.6% at 28 GHz. With 5G NR FR2 64-quadrature amplitude modulation (QAM) signals, the measured P
avg
of 11.7 dBm and an ACLR of -32.4 dBc are achieved at the EVM of -26 dB without digital pre-distortion (DPD). The DC power supply voltage is 3.3 V. The total chip size is 1.19 X 1.1 mm
²
. The measurement results show that the proposed balanced PA fulfills remarkable linearity, power gain, and competitive bandwidth with a compact chip size.