Patent ID: 7253718

Claim:
A transponder for supplying a code to a base station by varying a radio-frequency signal coming from the base station in a rhythm that corresponds to the code, the transponder comprising identification code generation means for generating the code; rectifier means which are arranged for AC coupling with a radio-frequency signal for applying a supply voltage to the generation means, and which rectifier means comprise at least one circuit acting as a rectifier; a modulation transistor having a main current path, and comprising a control electrode which is coupled for the reception of the code for producing a variable load of the rectifier means as a result of which the radio-frequency signal varies with said rhythm, the at least one circuit acting as a rectifier comprising the main current path of the modulation transistor, voltage adaptation means for adapting the voltage levels of the code and for supplying the code with the adapted voltage levels to the control electrode of the modulation transistor; and further rectifier means for applying a separate supply voltage to the voltage adaptation means.