A 10W Fully-Integrated LDMOS MMIC Doherty in LGA Package for 2.7GHz Small Cell Application
A two-stage integrated Doherty power amplifier (PA) was designed on latest LDMOS MMIC die and fully integrated with input splitter, output match and combiner as a module with 50ohm in-out characteristics for 2.7GHz LTE small cell application (an industry first). The two stage PA MMIC was fabricated with a size of 3 × 2.7 mm² and was mounted on a Printed Circuit Board (PCB) laminate in 7 × 7 mm² LGA package. An asymmetric integrated Doherty configuration was adopted with the uneven input power splitting network for better Efficiency. To improve linearity, the third-order intermodulation distortion (IMD3) was simulated and optimized by enhancing VBW (video bandwidth). The output combiner for integrated Doherty is simulated and designed carefully using novel capacitor cancellation method to get good bandwidth and Eff. Using a six-carrier LTE signal with a PAPR of 9 dB and a channel bandwidth of 20 MHz at 2.6 GHz, the full PA (an industry first) exhibited a power gain of 27 dB, 10W peak power, a power-added efficiency (PAE) of 41%, and an ACLR of -31dBc at an average output power of 31 dBm. It was lowered to -51dBc after a digital pre-distortion process.