Dual-Wideband Sequential Load-Modulated Balanced Amplifier Employing Continuous Mode and Harmonic Constraint Approach

This letter presents a novel methodology for optimizing the impedance trajectory in the design of a dual-wideband RF-input sequential load-modulated balanced amplifier (SLMBA). The proposed approach employs a continuous Class-F−1mode (CF−1M) for the control amplifier (CA) in the high-frequency (HF) band and utilizes a harmonic constraint technique to determine the optimal fundamental impedance in the low-frequency (LF) band, ensuring enhanced performance across the entire bandwidth. In addition, the impedance range of the balanced amplifier (BA) is correlated with the impedance trajectory of the CA for improved load modulation. To verify the proposed approach, a 0.7–1.1-/1.6–2.2-GHz dual-wideband SLMBA is implemented, achieving a saturated output power of 42.2–44.3 dBm with 50.4%–75.5% drain efficiency (DE) and 42.0%–53.0% 8-dB back-off DE. When driven by a 20-MHz modulation signal with 8-dB peak-to-average power ratio (PAPR), the prototype exhibits better than −50.0-dBc adjacent channel leakage ratio (ACLR) across the designed band after digital predistortion (DPD).