Dual-Band Pseudo-Doherty Load Modulated Balanced Amplifier Design with Arbitrarily Selected Frequency Bands

In this brief, for the first time, the design of a dual-band pseudo-Doherty load-modulated balanced amplifier (DB-PD-LMBA) with two arbitrary frequency bands is presented. It is accomplished by the adoption of generalized dual-band coupler and power divider. Besides, for size reduction and design simplicity, the finite off-state impedance of the active devices is fully utilized for removing the offset line, and conventional dual-band phase shifter is eliminated by employing an appropriate matching network design. In addition, a stop band between two target bands is introduced to enhance isolation. For validation, the proposed PA, operating at 1.5 GHz and 3.2 GHz, with a 10 dB OBO, was designed and prototyped. Measured results indicate that the fabricated circuit can deliver a drain efficiency of 68.7/73.5% at saturation (43/42 dBm), and 56.9/48.10% at 10 dB-OBO at the frequency of 1.5/3.2GHz.