A 2-to-18 GHz Power Amplifier With 31-dB Gain and ±0.5 dB In-Band Ripple Using Segmented Matching in 0.18- μ m SiGe BiCMOS

This paper proposes an ultra-wideband power amplifier (PA) covering theS-C-X-Kubands, realized in the HHGRACE 0.18-μm SiGe BiCMOS process. A frequency-domain characteristic-based segmented matching strategy is adopted, which leverages the substantial frequency-dependent variation of inductive/capacitive reactance within the operating band—particularly the inductive reactance of choke coils—to separately construct targeted low- and high-frequency impedance matching networks. Measurement results show that the PA achieves an ultra-wide bandwidth of 2–18 GHz (160% fractional bandwidth) with a gain of 31 dB at 10 GHz and a small gain ripple of ±0.5 dB. It maintainsS11S22OP1dB) of 14.7 dBm, a maximum saturated output power (PSAT) of 15.7 dBm and a peak power-added efficiency(PAE)of 14.88% at 8 GHz. The PA features a compact core area of 0.245 mm². Compared to state-of-the-art designs, the proposed PA realizes ultra-wide bandwidth, high gain, flat gain response, and compact size, making it suitable for modern ultra-wideband communication systems.