Dual mode efficiency enhanced linear power amplifiers using a new balanced structure

This paper presents a new balanced architecture to improve the power added efficiency (PAE) of a 3G handset power amplifier without trading-off its stringent linearity requirement. It is modified from the structure of our Switched Load Insensitive Power Amplifier (LIPA®). Power amplifiers using this modified balanced structure retain the main features of the LIPA and provide boosted PAE performance in low and high power mode. The novel balanced structure is implemented into 4×4mm
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power amplifier modules at both CELL and UMTS bands. For the UMTS band at +28dBm in high mode, 44.5% PAE is achieved, while in low mode at +16dBm, 21% PAE is achieved with an ACLR1 of −38dBc using WCDMA modulation. For CELL band at +28dBm in high mode, 43.5% PAE is achieved, while in low mode, 21% PAE is achieved at +16dBm with an ACLR1 of nearly −39dBc. Both PAs maintain good performance under load mismatch conditions due to the nature of the balanced structure.