Abstract: A PLL frequency synthesizer able to automatically set an appropriate operating mode of the voltage controlled oscillator is provided. The voltage controlled oscillator is operable in a plurality of operating modes each defining a different operating frequency range of the voltage controlled oscillator. The appropriate operating mode is selected based on an error signal detected by a phase/frequency detector of the PLL frequency synthesizer. A window comparator is used for switching to adjacent operating modes if the error signal exceeds or falls below predefined upper and lower error voltage limits.

Abstract: A frequency synthesizer usable in a wireless communication device is disclosed that may ensure a low phase noise and an improved performance. The frequency synthesizer has a phase locked loop comprising a controllable oscillator generating an output signal with an output frequency that can be adjusted within a predefined frequency range dependent on the value of a first control signal. A phase/frequency detector generates an error signal in response to a phase and/or frequency difference between an input signal generated by frequency dividing said output signal, and a reference signal. A loop filter generates the first control signal based on said error signal and outputs same to the controllable oscillator. A control unit generates a second control signal from the loop filter signal and provides the second control signal to the controllable oscillator, which is arranged for modifying the predefined frequency range based on the second control signal.

Abstract: A tunable constant GM circuit allows to compensate for temperature and process variations with high precision by correspondingly adjusting a resistance value and/or the ratio of transistor widths. Thus, in switched capacitor circuits the frequency behaviour, such as the settling time, may be controlled by providing a compensated bias to the transconductance amplifiers typically used in these circuits.

Abstract: A wireless local area network transceiver, an integrated circuit chip, a PLL (Phase Locked Loop) device and a method are provided that may reduce influences of switching noise. The frequency of an output signal of the PLL device is divided in a prescaler of the PLL device by a prescaler factor. The prescaler is operable in at least two modes with each mode having assigned a different prescaler factor. An accumulator is implemented in the PLL circuit for generating a mode switching signal for changing the mode of the prescaler. The generation of the mode switching signal is done by storing an accumulator value and processing a modulus function for updating the accumulator value. The provided technique may allow for reducing disturbances caused by switching the mode of the prescaler in the PLL circuit.

Abstract: A PLL frequency synthesizer able to automatically set an appropriate operating mode of the voltage controlled oscillator is provided. The voltage controlled oscillator is operable in a plurality of operating modes each defining a different operating frequency range of the voltage controlled oscillator. The appropriate operating mode is selected based on an error signal detected by a phase/frequency detector of the PLL frequency synthesizer. A window comparator is used for switching to adjacent operating modes if the error signal exceeds or falls below predefined upper and lower error voltage limits.

Abstract: Presented is a sensor system for the detection of thermal radiation, with a substrate (15) and several sensor elements (10) on the substrate (15), in which case at least one self-test device (53) is provided in order to generate heat which can be used for the heating of one or more sensor elements (10). The sensor elements (10) can be heated according to a typical time pattern during the self-testing process. Also presented is an advantageous process for the manufacture of the sensor system as well as an advantageous configuration of the total system, including signal processing.