Microwave Journal

Optimizing High Performance RF components for LTE and LTE Advanced Base Stations

May 12, 2011

Introduction – Trends in Wireless Systems

Increasing mobile phone minutes and mobile data usage continues to transform wireless base transceiver stations (BTS). As the number of users and higher data usage requirements increase, higher capacity networks require the deployment of more BTS systems, resulting in more transmit and receive channels per BTS system and in increasing medium to small cell sizes. Cellular providers, municipalities across the globe, and wireless original equipment manufacturers (OEM) are pushing for higher level integration and system efficiencies. Therefore, next generation BTS systems require proven and innovative high performance RF components to optimize cost, size and power efficiency.

1.0 NXP – Trends in Wireless Base Transceiver Station Systems

As air interface standards have evolved from Advanced Mobile Phone System (AMPS) in the eighties to the high-performance 3G and 4G systems of today and tomorrow, so have the architectures of BTS system transceivers. The high-speed data converters used in Base Transceiver Stations are evolving rapidly as radio transceiver design engineers drive to add LTE and LTE-Advanced functionality, as well as strive to reduce power and system size. These dynamics lead to data converters with more channels (moving from dual to quad), higher sampling rates (to 250 Msps and beyond for ADCs, to 1.25 Gsps and beyond for DACs). ADC input bandwidths are increasing to 100 MHz and potentially higher, and ADC linearity demands are getting higher; SFDR requirements reach as high as 95 dBc. DAC noise figures are required to be -163 dBm/Hz or lower, with 85 dBc SFDR linearity. ADC power consumption is driving to approximately 1 mW / Msps, while DAC power consumption is driving well below 1 mW / Msps.