A 24–30-GHz TRX Front-End With High Linearity and Load-Variation Insensitivity for mm-Wave 5G in 0.13-μm SiGe BiCMOS

A time-division duplex (TDD) transmit/receive (T/R) millimeter-wave (mm-wave) front-end in 0.13-
$\mu \text{m}$
SiGe BiCMOS for fifth generation (5G) is presented. The front-end is composed of a power amplifier (PA), a low noise amplifier (LNA), and a single-pole double-throw (SPDT) switch. At mm-wave bands, the traditional SPDT switch limits the output power of the front-end in transmit mode. In this article, an asymmetric SPDT switch is proposed with high-power-handling capability (simulated OP
$_{\mathrm {1\,dB}} > 28$
dBm), low insertion loss, and compact structure at 24–30 GHz. A balanced architecture is used to implement a high gain and high linearity PA with excellent input/output return losses and load-variation insensitivity. The effect of the feedback capacitor in the base of the cascode stage has been analyzed. The standalone PA achieves OP
$_{\mathrm {1\,dB}}$
/peak
$\text {PAE} > 16.9$
dBm/18.7% across 24–30 GHz and the OP
$_{\mathrm {1\,dB}}$
/peak PAE still exceeds >15.9 dBm/16.3% including the switch loss and compression. 5G NR FR2 64-QAM modulation tests demonstrate the high linearity of the balanced PA. At 28 GHz, the standalone PA shows the EVM of −29.93 dB/−26.06 dB with an average output power (
$P_{\mathrm {avg}}$
) of 10.15 dBm/12.16 dBm. The front-end in transmit mode shows the EVM of −29.63 dB/−26.02 dB with an average output power of 7.76 dBm/9.59 dBm. A wideband LNA is designed and exhibits a measured gain of 26 dB with a 3-dB bandwidth of 19–35 GHz, a noise figure (NF) < 5.3 dB at 24–30 GHz including the switch loss. The proposed front-end achieves high linearity in transmit mode and low NF in receive mode.