Base station distributed power supply box

This application note provides an illustrated overview of the five basic Distributed Base Station architectures in use today: legacy, split design, “hoteling” approach, zero-footprint, and capacity transfer system. The advantages and disadvantages of each approach are outlined.

In a 3G Base Station application, two converters are used to provide the +27V distribution bus voltage during normal conditions and power outages.

Multiple output designs may also employ a complex regulation scheme which senses multiple outputs to control the feedback loop. Voice-over-Internet-Protocol (VoIP), Digital Subscriber Line (DSL), and Third-generation (3G) base stations all necessitate varying degrees of complexity in power supply design.

This technique reduces opex by putting a base station into a “sleep mode,” with only the essentials remaining powered on. Pulse power leverages 5G base stations' ability to analyze traffic loads. In 4G, radios are always on, even when traffic levels don't warrant it, such as transmitting reference signals to detect users in the middle of the night.

A preferred power supply architecture for DSL applications is illustrated in Fig. 2. A push-pull converter is used to convert the 48V input voltage to +/-12V and to provide electrical isolation. Synchronous buck converters powered off of the +12V rail generate various low-voltage outputs.

This is when the PSU is no longer powering the PA, which is the main power draw, but still needs to power other electronics. The current target for low-load efficiency is about 30 W. Some OEMs would like to see that drop to nearly 10 W.