This letter presents a 5.15–6.425-GHz GaAs HBT power amplifier (PA) for emerging Wi-Fi 6E applications. As a wider range of the operating frequency is specified, a stagger-tuning neutralized differential PA architecture is proposed to extend the bandwidth. In addition, both the linearity and efficiency of the PA are improved using a continuous-mode harmonically tuned network for Class-F operation. The average gain of the proposed PA reaches 33 dB at 4.9–6.7 GHz. With the 80-MHz MCS11 802.11ax signal, the output power meeting error vector magnitude (EVM) of $-$ 40 dB reaches 18–20 dBm with maximum power-added efficiency (PAE) of 9.3% at 5.15–6.425 GHz.

This paper presents a monolithic microwave integrated circuit (MMIC) low noise amplifier (LNA) that is compatible with n257 (26.5–29.5 GHz) and n258 (24.25–27.5 GHz) frequency bands for fifth-generation mobile communications system (5G) and millimeter-wave radar. The total circuit size of the LNA is 2.5 × 1.5 mm2. To guarantee a trade-off between noise figure (NF) and small signal gain, the transmission lines are connected to the source of gallium nitride (GaN)-on-SiC high electron mobility transistors (HEMT) by analyzing the nonlinear small signal equivalent circuit. A series of stability enhancement measures including source degeneration, an RC series network, and RF choke are put forward to enhance the stability of designed LNA. The designed GaN-based MMIC LNA adopts hybrid-matching networks (MNs) with co-design strategy to realize low NF and broadband characteristics across 5G n257 and n258 frequency band. Due to the different priorities of these hybrid-MNs, distinguished design strategies are employed to benefit small signal gain, input-output return loss, and NF performance. In order to meet the testing conditions of MMIC, an impeccable system for measuring small has been built to ensure the accuracy of the measured results. According to the measured results for small signal, the three-stage MMIC LNA has a linear gain of 18.2–20.3 dB and an NF of 2.5–3.1 dB with an input–output return loss better than 10 dB in the whole n257 and n258 frequency bands.

A broadband GaN MMIC power amplifier (PA) with compact dimensions of 1.94 × 0.83 mm² is presented for 5G millimeter-wave communication. To guarantee output capability at the operating band edges where serious performance degradation is likely to occur, the appropriate large-signal matching model and optimal impedance domain need to be carefully determined through load-pull analysis. Broadband matching networks (MNs) in the lowpass form are thereafter developed based on the Chebyshev filter synthesis theory. Using high-pass interstage MN in conjunction with parallel RC lossy circuits to compensate for the transistor’s negative gain roll-off slope ensures a flat frequency response. The input MN is designed as a band-pass filter due to the reactance extracted from the input side of the stabilized device exhibiting series LC resonance characteristics. Measured on-wafer pulsed results for the proposed three-stage PA demonstrate up to 30.9 dBm of output power, more than 28.6 dB of small-signal gain, and a peak power-added efficiency (PAE) of 35.6% at 27 GHz. Both uniform gain and saturated output power (P_sat) are achieved across 24–30 GHz with fluctuations of less than 0.8 dB.

This letter presents a millimeter-wave power amplifier (PA) monolithic microwave integrated circuit (MMIC) for 5G new radio (NR) phased array base stations. The balanced/unbalanced-mode broadband power combining is used in the proposed PA to obtain higher linearity and efficiency at the 5G-n257/n258/n261 bands. Fabricated in a 0.15- $\mu$ m GaAs pHEMT process, the PA delivers 22-dBm saturated output power ( $P_{\mathrm{OUT}})$ with maximum power-added efficiency (PAE) of 36.5% under a 3-V supply at 23–30 GHz. With the 5G NR FR2 200-MHz 1-CC 64-QAM modulated signal, the PA achieves an average $P_{\mathrm{OUT}}$ of 13.5/12.5 dBm and PAE of 7.5%/7.6% with rms error vector magnitude (EVM) of $-$ 28/ $-$ 25 dB in balanced/unbalanced mode.

This paper presents the design procedure of an efficient compact monolithic microwave integrated circuit power amplifier (MMIC PA) in a 0.1 μm GaN-on-Si process for 5G millimeter-wave communication. Load/source-pull simulations were conducted to correctly create equivalent large-signal matching models for stabilized power cells and to determine the optimal impedance domain. The shorted stub with bypass capacitors minimizes the transistor’s output reactance, simplifying the matching objective to an approximate real impedance transformation (IT). With miniaturization as the implementation guide, explicit formulas and tabulated methods based on mathematical analysis were applied to synthesize the filtering matching networks (MNs) for the input and output stages. In addition, a CAD-dependent numerical optimization approach was used for the interstage MN that needs to cope with high IT ratio and complex loads. The continuous-wave (CW) characterization for the proposed two-stage PA demonstrated 19.8 ± 0.7 dB of small-signal gain, very flat output power (P_out) and power-added efficiency (PAE) at 4 dB gain compression of 32–32.4 dBm and 34–34.6%, respectively, over 24–30 GHz, with 37.1% of peak PAE at mid-frequency.