Abstract: A method and apparatus of controlling battery charging of an RF power amplifier are disclosed. The RF power amplifier is supplied by the battery when charging is progressing normally, but switches supply to the charger if the charging process is interrupted. A thermal detector detects a threshold temperature in the battery. A power controller provides feedback to a charger. The charger output is regulated in response to the battery feedback and the charging is suspended when the battery temperature exceeds the threshold temperature. After the charging is suspended, the charger output is regulated to maintain a minimum output voltage. Using a signal from logic circuitry, if charging has been suspended a first switching means disconnects the negative terminal of battery from ground and a second switching means connects the RF power amplifier to the charger.

Abstract: The present invention provides a circuit arrangement wherein in operation a radio frequency power amplifier is supplied by the battery when charging is progressing normally, but switches supply to the charger if the charging process is interrupted. Thus the RF power amplifier receives approximately 4.2V from the battery, or approximately 4.4V±5% from the charger if charging of the battery is suspended. This also allows operation solely from the charger in the absence of a battery. Thus the present invention enables continuing operation of the device if charging is suspended, whilst limiting the voltage level to the RF power amplifier to approximately 4.4V±5%.

Abstract: A subscriber unit (103) for a cellular communication system (100) comprises a first location processor (117) which determines a location estimate from signals transmitted from satellites (105) and from satellite information related to the satellites (105). The satellites (105) may be Global Positioning System (GPS) satellites. The subscriber unit (103) also comprises a receiver (115) which receives the satellite information, and further comprises a second location processor (111) which determines location estimates based on uplink or downlink transmissions in the cellular communication system (100). An update controller (121) determines an update time for the satellite information in response to the location estimates of the second location processor (111). Accordingly, the update operation may be optimised for the specific movement of the subscriber unit (103) without requiring satellite based location estimates.