Abstract:
A temporary anti-rollback table—which is cryptographically signed, unique to a specific device, and includes a version number—is provided to an electronic device requiring a replacement anti-rollback table. The table is verified by the device, and loaded to memory following a reboot. The memory image of the table is used to perform anti-rollback verification of all trusted software components as they are loaded. After booting, the memory image of the table is written in a secure manner to non-volatile memory as a replacement anti-rollback table, and the temporary anti-rollback table is deleted. The minimum required table version number in OTP memory is incremented. The temporary anti-rollback table is created and signed using a private key at authorized service centers; a corresponding public key in the electronic device verifies its authenticity.
Abstract:
The invention concerns a device for providing a spread frequency clock signal, comprising: -an input (51) to receive a first clock signal having a first frequency; -a programmable clock divider (52) to generate the spread frequency clock signal from the first clock signal; -a first Feedback Shift Register (21), FSR, comprising at least one stage, the FSR being adapted to generate any of an odd number M of different values, the FSR being adapted to pseudo-randomly generate a first sequence of first output values, each corresponding to one of said M different values, and to provide a first output value, according to the sequence, during each clock cycle of the spread frequency clock signal; -a control unit (22) adapted to select a division factor of the programmable clock divider based on the first output value of the FSR during each clock cycle of the spread frequency clock signal; -an output (53) for providing the spread frequency clock signal.
Abstract:
High-speed RF differential, Quadrature, divide-by-2 clock divider designs are based on inverters and clocking circuits connected in a serial ring formation. In one embodiment, only NMOS transistors are used in the inverters, and only PMOS transistors are used in the clocking circuits. This structure uses only 12 transistors. The input can be coupled directly to a VCO output, and provides minimum loading, as each VCO output is connected to only two transistors. Another embodiment comprises clocked inverter stages connected in a serial ring configuration with inverters between stages. The RF clock (or VCO signal) is used at the outer side of the inverters for speed improvement. In both circuits, positive and negative clock inputs are connected alternately at each stage of the ring.
Abstract:
Time frames (TFs) are allocated for performance of transactions of a low latency data stream (LLDS) and a best effort data stream (BEDS) in Bluetooth®-like equipment, wherein payload carrying packets of the different data streams are equal in size, each occupying multiple TFs. An overrule mechanism enables uncompleted transactions of one data stream to continue as needed into TFs allocated to another data stream. Every TF within an allocation window (AW) is individually allocated to the LLDS or the BEDS, and plural TFs immediately following the AW form a guard space between adjacent AWs, the guard space being allocated to neither the LLDDS or the BEDS. Configuration of the AW and of the guard space guarantees the LLDS a first opportunity to transmit a payload carrying packet and continued opportunities to retransmit the packet until successful, after which the BEDS is given an opportunity for transmission and possible retransmissions.
Abstract:
There is disclosed a driver circuit for a power amplifier of class D type having a segmented architecture with at least one current branch which can be powered down in a low power mode of operation of the circuit. The branch comprising a switch with a cascode MOS transistor, the circuit further comprises a bias circuitry adapted for dynamically generating a dynamic bias control signal so as to cause the cascode MOS transistor of the switch to be ‘Off’ in the low power mode.
Abstract:
Problems arising from a pre-emphasis filter, particularly an infinite-impulse-response filter, in a signal modulator are solved by detecting sequences of the same bit or symbol in a modulation signal and compensating the corresponding d.c. offset in the signal generated by the pre-emphasis filter without real-time feedback. The amount of offset compensation can be defined during design of the modulator or adjusted or calibrated during production. It is not necessary to change the transfer function of the pre-emphasis filter, but only to correct the d.c. offset of the filter output signal.
Abstract:
An electrical interface circuit is disclosed. The circuit comprises a microphone circuit (100); a battery charger circuit (200); and an electrical connector (300) for connecting said electrical interface circuit to an external device. The electrical connector has a pin (302) on which signals are multiplexed for connecting either the battery charger circuit to an external supply voltage or the microphone circuit to an external microphone. The battery charger circuit comprises an amplifying circuit (202) for controlling voltage or current to a battery (400) at battery charging and a p-type power transistor. The pin is connected to the microphone circuit and to a source of the p-type power transistor, and when a voltage applied to the pin exceeds the battery voltage, the p-type power transistor will provide current from the pin to the charger circuit, and otherwise the charger circuit and battery is disconnected from the pin. A method of multiplexing signals on the electrical interface circuit is also disclosed.
Abstract:
A frequency conversion device for transforming a frequency of an input signal, the device comprising: a signal generator for providing a plurality N of first signals at a first frequency, where N≧1, from an input signal having an in-phase component I and a quadrature signal component Q; an oscillator for generating N parallel oscillation signals, wherein the N oscillation signals are stepped in phase with respect to one another; a mixer comprising N mixing components, each mixing component being coupled to receive a respective one of the plurality of first signals and coupled to receive a respective oscillation signal for mixing the respective first signal with the corresponding oscillation signal to provide an output signal; and a common amplifier for receiving the N output signals from the N mixing components in N sequential phases for transmission.
Abstract:
A receiver receives a desired radio sub-channel transmitted with an unwanted radio sub-channel by producing signal branches from a received radio signal by treating orthogonal components of the received signal separately and also by using one or both of oversampling and multiple receive antennas. Channel estimates for both the desired and unwanted radio sub-channels are produced for signal branches. The unwanted radio sub-channel bits are estimated from a non-stacked form of the received radio signal. The channel estimates and the estimate of the unwanted radio sub-channel bits are used to reconstruct unwanted radio sub-channel components separately for signal branches. Desired radio sub-channel signal branches are produced by subtracting a corresponding one of the reconstructed unwanted radio sub-channel components from signal branches. A non-stacked desired signal is produced by combining the desired radio sub-channel signal branches. The non-stacked desired signal is processed to receive the desired radio sub-channel.
Abstract:
An RF front end circuit has a common impedance matching network connected to an output terminal, a first power amplifier arranged to drive power to the output terminal through the common impedance matching network, a second power amplifier adapted to drive power to the output terminal through the common impedance matching network, a second impedance matching network, and a reference terminal at a reference voltage. The second impedance matching network has at least a first connection path to the reference terminal, a second connection path to the second power amplifier and a third connection path to the common impedance matching network. The second impedance matching network also includes a first impedance switch configured to open the first connection path responsive to the second power amplifier being put into an OFF state.