A circuit comprises an active filter with linear elements and a tuning circuit with linear elements of the same type as the filter circuit. A backward counter generates a count value that represents a time constant of the tuning circuit. The initial value of the backward counter contains information concerning the relationship between the time constant of the filter circuit and the tuning circuit. A decoder creates a digital code responsive to the count value which is used to switch an array of ...

A comparator comprises a switching means for supplying two different threshold voltages to the comparator upon a first and a second control signal, respectively. The second control signal is enabled by a rising or a falling edge of the comparator output that is coupled to a control means providing the second control signal. The time interval that a varying input signal requires to change its amplitude crossing and in between the two threshold voltages can thus be detected by two subsequent risin...

A FET square multiplier is disclosed that transforms an input signal into two currents I.sub.1 and I.sub.2, the difference of which is proportional to the square of the input signal. A first and a second FET are connected at their drains and are source-coupled to the source of a third FET whose transconductance is twice the transconductance of the first and the second FET. The common source node is biased by a constant current source. The FETs are operated in the saturation region to exploit the...

A radio frequency signal level is determined by generating an AC reference voltage from a DC reference voltage and determining an envelope of the AC reference voltage in an envelope detector having substantially the same composition as an envelope detector for determining the envelope of the radio frequency signal. The AC reference voltage substantially eliminates any DC offset and thus induces a high immunity against temperature and power supply variations. Moreover, using substantially the sam...

An automatic gain controller for transceiver elements uses a digital topology to achieve an efficient and rapid gain settling so that an output signal of the variable gain section is within a predefined range. In one embodiment, an input signal is periodically sampled and latched so as represent the gain excess of a variable gain section. An accumulator, including an adder having saturation characteristics and a latch as a feedback element, creates a number for a new gain setting so that the var...

A receiver, an integrated circuit chip and a method are provided for estimating the power of a digitally modulated signal received by the receiver in a communication system. The method comprises determining in-phase and quadrature-phase values of a phase constellation system relating to the received signal, calculating at least one modified in-phase value and at least one modified quadrature-phase value relating to the phase constellation system rotated by a predetermined angle, and determining ...

An automatic power level control circuit provides output power control of a transmitter device as used in wireless LAN applications in that an output signal is detected and a corresponding control voltage of a DAC in the base band section is corresponding adjusted. Preferably, the measurement of the output power is carried out during a first transmit cycle and the DAC is adjusted after completion of the first transmit cycle and prior to the begin of a subsequent transmit cycle. Thus, a reliable ...

A receiver is provided for receiving a digitally modulated signal in a communication system. The receiver comprises a signal input unit adapted for determining at least one in-phase and at least one quadrature-phase value of the received signal. The receiver further comprises a signal generator connected to receive the in-phase and quadrature-phase values and to generate at least one modified in-phase value and at least one modified quadrature-phase value of a rotated phase constellation system....

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.

An electronic circuit with an improved current stabilization operating in an RF transceiver or receiver, e.g. in a wireless local area network system, and a corresponding method is provided for generating a supply current and supplying the generated supply current to at least two subunits of the electronic circuit. The at least two subunits are connected in parallel to each other. Each of the subunits receives an input voltage at an input transistor in the first one of at least two parallel curr...