Abstract: Techniques involving the generation of signals at particular frequencies are disclosed. For instance, an apparatus may include an oscillator module, a synthesizer module, and a control module. The oscillator module produces an oscillator signal having a first frequency. From the oscillator signal, the synthesizer module produces an output signal having a second frequency. A frequency multiplier corresponds to the first and second frequencies. The control module selects the first frequency and the frequency multiplier such that a difference between the second frequency and a nearest integer multiple of the first frequency is greater than a predetermined threshold. As a result, reductions in spurious outputs may be achieved.

Abstract: Methods and apparatus to fine gain and/or phase adjustment of analog quadrature filters are described. In one embodiment, gain and/or phase of an analog quadrature filter may be digitally controlled by switching one or more resistors coupled to the quadrature filter. Other embodiments are also described.

Abstract: Techniques involving the generation of signals at particular frequencies are disclosed. For instance, an apparatus may include an oscillator module, a synthesizer module, and a control module. The oscillator module produces an oscillator signal having a first frequency. From the oscillator signal, the synthesizer module produces an output signal having a second frequency. A frequency multiplier corresponds to the first and second frequencies. The control module selects the first frequency and the frequency multiplier such that a difference between the second frequency and a nearest integer multiple of the first frequency is greater than a predetermined threshold. As a result, reductions in spurious outputs may be achieved.

Abstract: Methods and apparatus to fine gain and/or phase adjustment of analog quadrature filters are described. In one embodiment, gain and/or phase of an analog quadrature filter may be digitally controlled by switching one or more resistors coupled to the quadrature filter. Other embodiments are also described.

Abstract: A circuit arrangement having a plurality of variable capacitance elements such as varactors is described, the varactors having associated electronic control means which controls the capacitance of the variable capacitance elements over a control range. The control range is such that for any particular variable capacitance element a complete variation from a lowest to a highest capacitance is obtained from only a portion of the control range.

Abstract: A variable capacitance network is disclosed, comprising a plurality of capacitance arms connected in parallel with each other between first and second terminals of the network. Each capacitance arm has a varactor and a series capacitor in series with the varactor A control input applies a common control signal to the junctions between the varactors and their associated series capacitors, to allow for simultaneous control of each varactor.

Abstract: A variable capacitance network is disclosed, comprising a plurality of capacitance arms connected in parallel with each other between first and second terminals of the network. Each capacitance arm has a varactor and a series capacitor in series with the varactor A control input applies a common control signal to the junctions between the varactors and their associated series capacitors, to allow for simultaneous control of each varactor.

Abstract: A circuit arrangement having a plurality of variable capacitance elements such as varactors is described, the varactors having associated electronic control means which controls the capacitance of the variable capacitance elements over a control range. The control range is such that for any particular variable capacitance element a complete variation from a lowest to a highest capacitance is obtained from only a portion of the control range.

Abstract: A variable capacitance network is disclosed, comprising a plurality of capacitance arms connected in parallel with each other between first and second terminals of the network. Each capacitance arm has a varactor and a series capacitor in series with the varactor A control input applies a common control signal to the junctions between the varactors and their associated series capacitors, to allow for simultaneous control of each varactor.

Abstract: A controllable filter arrangement comprises a filter network for filtering an input signal of the filter arrangement, and a transistor, the transistor being configured as a voltage-follower having a controllable current source in its output circuit for providing a controllable DC transistor output current, an output terminal of the voltage-follower being connected to the filter network such that a cut-off frequency of the filter can be controlled by variation of the DC current supplied by the current source. The filter network may be a single-pole RC network and the output of the follower may be connected to an additional capacitor (or resistor) of the network which is coupled to the junction of the existing capacitor and resistor.