Transponder

Abstract

An identification transponder (IDT) for supplying an identification code to a base station (BS) varies an RF signal transmitted by the base station (BS) in a rhythm that corresponds to the identification code. The identification transponder (IDT) has identification code generation means (IDCG) for generating the identification code, rectifier means (RTF) for AC coupling with the base station (BS) for applying a supply voltage (V1) to the identification code generation means (IDCG), a modulation transistor (TM), voltage adaptation means (VADPT) for adapting the voltage levels of the identification code and for supplying the code with adapted voltage levels to a control terminal of the modulation transistor (TM), and further rectifier means (FRTF) for the aforementioned AC coupling to the base station (BS) for applying a separate supply voltage (V2) to the voltage adaptation means (VADPT). The modulation transistor (TM) may perform two tasks: the task of rectifying the RF signal, and the task of supplying a variable load to the rectifier means (RTF). The variable load varies in the rhythm. As a consequence, the input current of the rectifier means (RTF) is varied in the rhythm, which in its turn varies the RF signal. This variation in the RF signal is detected in the base station (BS).

Dependencies are inferred from the claim text.