Battery power supply for radiofrequency transmitter

A power supply device for an RF transmitter module, the device comprising at least one battery and at least one capacitor forming an energy storage circuit electrically connected in parallel between the battery and the RF transmitter module, the power supply device also including voltage-raising means for charging the capacitor to a storage voltage that is higher than the voltage delivered by the battery during an initial charging stage, the voltage-raising means comprising an inductor (L) and a diode connected in series between the battery and the capacitor, and switch means suitable for acting during the initial charging stage to cause energy to be accumulated periodically in the inductor, and then to cause the accumulated energy to be transferred into the capacitor, the device also including a control module suitable for generating a control signal (SC) for the switch means, firstly to disconnect the capacitor from the RF transmitter module during the initial capacitor-charging stage, and secondly to disconnect the voltage-raising means from the battery during a subsequent capacitor discharge stage, the device being characterized in that said control signal (SC) is predetermined and of variable period, and is suitable, during each period, to cause:

• said switch means to close over a fixed duration (TON) calculated so as to enable the current (IL) flowing through the inductor to increase from a value of zero up to a predefined limit value (ILpeak);
• and
• said switch means to open over a duration (TOFF) that is variable and a function of the voltage (VC) across the terminals of the capacitor, and that is defined in such a manner as to enable the current (IL) flowing through the inductor to decrease from said predefined limit value (ILpeak) to a value of zero.