Begrenzung der Verlustleistung eines HF-Leistungsverstaerkers im Multislot Betrieb durch Beschraenkung der Anzahl der TX Slots in Abhaengigkeit spezifischer Umgebungsbedingungen
Original Publication Date: 2004-Jul-25
Included in the Prior Art Database: 2004-Jul-25
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In a mobile phone being operated in GPRS (Radio Frequency) class 12 mode (4TX) the heat generation caused by the RF (Radio Frequency) power amplifier can not be neglected despite the reduction of maximum output power in multi slot mode (e.g. up to 6dB for 4TX). Detailed evaluations show that permanent class 12 operation in HTR (High Temperature Range) is not feasible with standard components even at NCD (Normal Conditions for PA Power Dissipation). Only short-term operation is possible in HTR whereby the duration depends on dissipated power and ambient temperature. The evaluations are valid for the case that no special HW (hardware) measures are implemented inside the phone to reduce power dissipation of RF power amplifier (e.g. buck converter, switched matching, high efficiency PA). If the critical temperature is exceeded it's compulsory to reduce the power dissipation to prevent the PA or other components from being damaged by overheat or to avoid that these components are operated outside their specified temperature range. The reduction of dissipation power can be achieved by reducing GPRS class or PA output power. The reduction of GPRS class is advantageous, because it is preferred to continue transmission with reduced data rate than to increase the risk of dropped packet transfer due to low radiated power. Changing the GPRS class during data transfer is not supported by every base station. So it is necessary to reduce the PA output power if the request to change GPRS class is ignored by the base station. Derating the output power results in reduced radiated power which increases the risk of dropped packet transfer.