An efficient mobile phone transmitter amplifier with an adapted power supply voltage

摘要

The power supply voltage for an RF power amplifier 12 in a mobile phone is varied in dependence on the baseband gain control signal. This raises the amplifier efficiency when the amplifier input signal level is low. The baseband gain control signal is modified by a non-linear shaping circuit 18 (figure 5) which supplies a reference signal to the DC-DC converter 14 supplied by a battery 16. A look-up table is not needed for producing the reference signal, which can now be generated promptly and easily for each transmission slot.