Multi band Multi standard 50W high efficiency and highly linear Power Amplifier for Macro Base Stations

Abstract

In this paper, design of multi band multi standard LDMOS 50W high efficiency, high gain and highly linear Asymmetric Doherty Power Amplifier (ADPA) in a common PCB without layout changes to cover all lower 3gpp frequency bands from 729 to 960MHz was presented. To cover different wireless frequency bands, different passive matching components for different frequency bands were used without changing the layout. Quarter wave line lengths were adjusted to cover various bands by providing options with a series of capacitors on quarter wave lines. Care has been taken to keep same matching circuit for at least two adjacent frequency bands. This paper also proposed a drain feed design technique to achieve good Digital Pre Distortion (DPD) performance. The ADPA was characterized with LTE 5MHz signal, achieved a total gain of 52dB with final Doherty Power-Added-Efficiency reaching to 48% over the frequency range at 47dBm output power with output power back off of 8dB from peak. The uncorrected Adjacent Channel Power Ratio (ACPR) over the frequency range observed was −35 dBc, after DPD correction ACPR observed was −63dBc, the LTE 5 MHz 64 QAM Error vector magnitude (EVM) observed was 3.5%, and the ADPA peak power achieved was greater than 55.5dBm.