Abstract: Power extracted from an antenna inductively coupled to an alternating magnetic field is regulated to provide voltage supplies. In some implementations, a first voltage supply (e.g., 3.8 volts) provides regulated voltage to analog circuits and a second, lower, voltage supply (e.g., 1.4 volts) provides regulated voltage to digital circuits. The first voltage supply is regulated, using shunt regulation, by a first voltage regulator circuit. The second voltage supply is regulated, using a series regulation, by a second voltage regulator circuit. The second voltage regulator circuit is supplied by the shunted current from the first voltage regulator. Excess shunt current provided by the first regulator circuit can be bypassed (e.g., bypassed to ground). The second voltage regulator circuit can use a timer circuit to control the amount of charge transferred to a second voltage supply rail. The timer circuit can compensate for different currents from the first voltage regulator circuit.

Abstract: Power extracted from an antenna inductively coupled to an alternating magnetic field is regulated to provide voltage supplies. In some implementations, a first voltage supply (e.g., 3.8 volts) provides regulated voltage to analog circuits and a second, lower, voltage supply (e.g., 1.4 volts) provides regulated voltage to digital circuits. The first voltage supply is regulated, using shunt regulation, by a first voltage regulator circuit. The second voltage supply is regulated, using a series regulation, by a second voltage regulator circuit. The second voltage regulator circuit is supplied by the shunted current from the first voltage regulator. Excess shunt current provided by the first regulator circuit can be bypassed (e.g., bypassed to ground). The second voltage regulator circuit can use a timer circuit to control the amount of charge transferred to a second voltage supply rail. The timer circuit can compensate for different currents from the first voltage regulator circuit.

Abstract: Methods and apparatus provide multiple input voltage regulation in which one regulator is selected for operation based on input power conditions. In one example, a dual input voltage regulator system in a combination smart card selects between contact and contactless (e.g., RF) operation based on which power source provides the highest available voltage level. A single transistor drop architecture provides low drop-out voltage regulation capability without substantially increased transistor size. In some implementations, multiplexed control of the regulators for each of a number independent power source inputs may be arranged to substantially reduce or prevent reverse current flow through regulators connected to inactive power inputs.

Abstract: A digital circuit is disclosed for detecting clock activity in an integrated circuit (IC) device. In one implementation, a clock detection circuit can include two flip flops. A first flip flop detects activity on the clock being tested (e.g., the flip flop is set when a positive clock edge is detected). A second flip flop is coupled to the output of first flip flop and is operable by an enable signal to sample the output of the first flip flop. The output of the second flip flop is asserted as active, when a positive clock edge occurs between the release of the reset signal on the first flip flop and the assertion of the enable signal on the second flip flop. In some implementations, one or more additional flips can be interposed between the first and second flips to control metastability.

Abstract: Power extracted from an antenna inductively coupled to an alternating magnetic field is regulated to provide voltage supplies. In some implementations, a first voltage supply (e.g., 3.8 volts) provides regulated voltage to analog circuits and a second, lower, voltage supply (e.g., 1.4 volts) provides regulated voltage to digital circuits. The first voltage supply is regulated, using shunt regulation, by a first voltage regulator circuit. The second voltage supply is regulated, using a series regulation, by a second voltage regulator circuit. The second voltage regulator circuit is supplied by the shunted current from the first voltage regulator. Excess shunt current provided by the first regulator circuit can be bypassed (e.g., bypassed to ground). The second voltage regulator circuit can use a timer circuit to control the amount of charge transferred to a second voltage supply rail. The timer circuit can compensate for different currents from the first voltage regulator circuit.

Abstract: Methods and apparatus may provide for multiple input voltage regulation in which a current supplied to an output node divides among voltage regulators according to their respective input voltages when the difference in input voltages falls within a voltage range. When the difference in input voltages falls outside of the voltage range, then the current to the output node is supplied substantially through the voltage regulator with the highest input voltage. In some implementations, the voltage range may be determined, at least in part, by a transistor gate-to-source threshold voltage characteristic. In one example, a dual input voltage regulator system in a combination smart card supplies current from contact and/or contactless (e.g., inductively coupled) power sources based on a relative voltage between the respective input voltages.

Abstract: A method and apparatus for deactivating an identification device or RFID tag, such as an e-passport or an ID card that has been revoked, has expired, or is invalid. A programmable memory circuit is coupled to a controlling circuit that is coupled to a shorting circuit that may activate or deactivate the operation of the identification device.

Abstract: Methods and apparatus may provide for multiple input voltage regulation in which a current supplied to an output node divides among voltage regulators according to their respective input voltages when the difference in input voltages falls within a voltage range. When the difference in input voltages falls outside of the voltage range, then the current to the output node is supplied substantially through the voltage regulator with the highest input voltage. In some implementations, the voltage range may be determined, at least in part, by a transistor gate-to-source threshold voltage characteristic. In one example, a dual input voltage regulator system in a combination smart card supplies current from contact and/or contactless (e.g., inductively coupled) power sources based on a relative voltage between the respective input voltages.

Abstract: Methods and apparatus provide multiple input voltage regulation in which one regulator is selected for operation based on input power conditions. In one example, a dual input voltage regulator system in a combination smart card selects between contact and contactless (e.g., RF) operation based on which power source provides the highest available voltage level. A single transistor drop architecture provides low drop-out voltage regulation capability without substantially increased transistor size. In some implementations, multiplexed control of the regulators for each of a number independent power source inputs may be arranged to substantially reduce or prevent reverse current flow through regulators connected to inactive power inputs.

Abstract: A smart card operates within an electromagnetic field produced at radio or microwave frequencies and rectifies the received field to provide power for operation of a load device. The field strength received by the smart card varies due to differing strengths of generation sources, proximity of the card to a source, and a presence of other active cards in the field. The amount of transmitted power available to supply an operation of the smart card varies in proportion to the strength of the field received by the card. The smart card detects the amount of power available and adjusts a performance point of the smart card load so that an amount of power consumed is appropriate to the amount of power received. In the event that the amount of power received exceeds an amount of power required, a shunting device is employed to regulate power to the smart card load.

Abstract: A method and apparatus for deactivating an identification device or RFID tag, such as an e-passport or an ID card that has been revoked, has expired, or is invalid. A programmable memory circuit is coupled to a controlling circuit that is coupled to a shorting circuit that may activate or deactivate the operation of the identification device.