Abstract: Power reception circuits employable in portable data devices (e.g., smart cards) to derive power and/or data from an input AC power signal (e.g., an ASK modulated carrier signal). In one embodiment, the power reception circuit comprises a power rectifier (120), a shunt rectifier (142) and a shunting element (132). The power rectifier (120) is adapted to rectify the input power signal, yielding a rectified output waveform. The shunt rectifier (142) is connected in parallel with the power rectifier (120). The shunting element (132) is connected to the shunt rectifier (142) and is operable to regulate an output voltage or current waveform produced at the output of the power rectifier (120). In another embodiment, the power reception circuit includes an analog circuit (610) for recovering data from a modulated carrier signal. A decoupling device (630) isolates the analog circuit (610) from impedance variations of a load. A shunt device (640) diverts undesired current from the load.

Abstract: A portable data device employs an integrated circuit having a signal processor that receives a power signal from an external source via a power node. A decoupling device is placed between the power node and the signal processor. An energy reservoir is placed in parallel with the signal processor, which acts in concert with the decoupling device to isolate the effects of the signal processor from the rest of the integrated circuit.

Abstract: Reliable communication is provided by a radio frequency identification system comprising at least one of an interrogator (102) and a transponder (104). The interrogator (102) transmits a plurality of interrogator frames (106) and receives at least one of a plurality of transponder frames (114). The transponder (104) transmits the plurality of transponder frames (114) and receives at least one of the plurality of interrogator frames (106). Each frame in the plurality of interrogator frames and the plurality of transponder frames includes an initialization sequence (108 and 116), at least one information sequence of a first predetermined length (110 and 118), and a check sequence of a second predetermined length (112 and 120) for each information sequence.