Choosing linear regulators for mobile telecom apps

摘要

Modern telecommunication electronics, such as digital circuits in mobile phones, require supply voltages that are approaching 1.2 V and even lower. Current consumption, on the other hand, will likely remain the same or even increase since mobile phones are absorbing an increasing array of functions. At the same time, battery voltage is not likely to drop in the near future from the levels of Li-ion or Li-polymer, which is around 3.6 V. The dc/dc converter IC is thus being pressed into dual service: both to manage power and reduce the number of discrete linear regulators. The need for discrete linear regulator ICs, both single and multiple types, does not diminish, however. Either power management circuits do not have enough linear regulators for feeding sensitive analog and RF circuits or they do not offer solution in most critical places. The latter may be due to cross coupling from dc/dc converters or other circuitry in power management ICs or poor performance from integrated linear regulators.