According to an example embodiment, there is a magneto-resistive (MR) sensor having an operation mode and a test mode. The MR sensors comprise a first plurality of first MR elements and a second plurality of second MR elements. A first signal processing unit is connected to the first plurality of first MR elements for generating a first output signal; the first output signal has a first phase. As second signal processing unit is connected to the second plurality of second MR elements for generating a second output signal; the second output signal has a second phase. There is a third signal processing unit or processing the first and second output signals; the third signal processing unit is adapted to activate one of the operation mode and the test mode on the basis of the first and second output signals. When the first and second plurality of first and second MR elements are exposed to a homogeneous magnetic field, the third signal processing unit is adapted to activate the test mode.
The semiconductor device (11) of the invention comprises a circuit covered by a passivation structure (50). It is provided with a first and a second security element (12A, 12B) which comprise local areas of the passivation structure (50), and with a first and a second electrode (14,15). The security elements (12A, 12B) have a first and a second impedance, respectively, which impedances differ. This is realized in that the passivation structure has an effective dielectric constant that varies laterally over the circuit.Actual values of the impedances are measured by measuring means and transferred to an access device by transferring means. The access device comprises or has access to a central database device for storing the impedances. The access device furthermore may compare the actual values with the stored values of the impedances in order to check the authenticity or the identity of the semiconductor device.
A field effect device includes at least one segmented field plate, each of the at least one segmented field plates having a plurality of segments that each form a plate of a capacitor, wherein the field effect device is connected to an electronic element that dynamically connects selected segments to selectively set a gate-to-drain and a drain-to-source capacitance. An ultrasonic device includes a transducer coupled to a switching device that switches the transducer between a transmit mode and a receive mode switching device, wherein the switching device includes the field effect device.
The circuit for controlling the oscillation frequency of an oscillation loop (66) has among others the following components--a first tunable capacitor unit (80) for providing a selectable amount of capacitance to the oscillator loop in accordance with a stored setting, and for controlling the oscillation frequency of the oscillator loop, and--a volatile storage unit (84) adaptated to store the setting of the tunable capacitor unit. The circuit further comprises a supply line (52) to the volatile storage unit and at least one other supply line (44) for the other components of said circuit. The supply line to the volatile storage unit is independent of said at least one other supply line, so that the volatile storage unit can be powered independently of other components of said circuit.
A transmitter comprises a power amplifier which has an amplifier power-supply input and an output to supply a transmission signal with an output power. A power supply has power supply outputs to supply a first power supply voltage and a second power supply voltage. A switching circuit is arranged between the power supply outputs and the amplifier power-supply input. A controller has an input to receive a power change command to control: first the switching circuit to supply the first power supply voltage to the amplifier power-supply input, and the power supply to vary a level of the second power supply voltage, the level of the second power supply voltage being lower or higher than a level of the first power supply voltage if the power change command indicates that the output power has to decrease or increase, respectively, and secondly the switching circuit to supply the second power supply voltage to the amplifier power-supply input.