Patent ID: 7119610

Claim:
A circuit arrangement for analog/digital conversion of a voltage which is ASK modulated by alternating the amplitude between a low and a high level, comprising: a rectifier circuit located downstream of a radio-frequency input; a first charging circuit and a second charging circuit which are connected in parallel to one another to an output of the rectifier circuit, wherein each of the first and second charging circuits produces a charging voltage; a decoupling device which decouples the charging voltages at a prescribed ratio between the respective charging voltages of an input voltage for the rectifier circuit; and an evaluation circuit which ascertains a level change from the ratio between the charging voltages, wherein the discharge and/or charging time of at least the first charging circuit is shortened when the input voltage is no longer within a voltage window defined by the respective charging voltages, and the discharge and/or charging time of at least the first charging circuit is lengthened when the input voltage is within the voltage window.