A 5/6 GHz Compact, Dual-Band, and Highly Linear Wi-Fi 6E SiGe HBT Power Amplifier Using Q-Modulated Switched Capacitor Interstage Matching Network and Optimized Output Stage

This Work presents a compact, highly linear SiGe HBT power amplifier (PA) for Wi-Fi 6E application. To cover the entire $5 / 6 \mathrm{GHz}$ band, a Q modulated switched capacitor interstage matching network, a broadband transformer balun, and an optimized output stage layout are co-designed With these circuit design techniques, the proposed PA maintains similar small/large signal performance at $5 / 6 \mathrm{GHz}$ band. The two-stage PA is fabricated in $0.35-\mu \mathrm{m}$ SiGe HBT Bi-CMOS technology, with its chip DIE size of $0.73 \mathrm{~mm}^{2}$. Measured small signal gains are $27.0 / 27.0 \mathrm{~dB}$ at $5 / 6 \mathrm{GHz}$ band, with gain variation less than 0.12 dB at any 80 MHz channel bandwidth(BW). Linear output power ($P_{\text {AVG }}$) is $18.2 / 18.7 / 18.1 / 18.3 / 17.9 / 17.9 \mathrm{dBm}$ ($E V M=-32 \mathrm{~dB}$) at $5250 / 5570 / 5850 / 6025 / 6585 / 6985 \mathrm{MHz}$ under an 802.11ac MCS9 VHT80 signal. The SiGe PA also supports 802.11ax MCS11 VHT160 signal with $\mathbf{P}_{\text {AVG }}$ of 7.1 dBm, at EVM $=-38 \mathrm{~dB}$.