A voltage controlled oscillator (VCO) circuit and method achieves linearized frequency tuning over an extended range of analog tuning voltage by implementing a magnetic balun/transformer for biasing and coupling varactor elements. An active negative transconductance circuit of cross-coupled transistors have drains connected with a resonant tank circuit and at least a first varactor element having ends connected to respective first ends of respective first coils of a respective first and second magnetic balun. Respective second ends of respective first coils of respective first and second baluns are connected to a first reference supply voltage. A second varactor element has ends connecting respective first ends of respective second coils of said first and second baluns. A sinking of a bias current through the resonant tank circuit and the transconductance circuit generates an oscillating signal. A calibration method achieves precise VCO gain over wide tuning voltage range, thereby enhancing VCO linearity.

The present application relates to a differential Colpitts voltage-controlled oscillator (VCO) circuit, which comprises a pair of transistors with control terminals biased by a common biasing voltage and a pair of couplers arranged to cross-couple corrector/drain of the transistors and the base/gate of the differential transistors. The pair of couplers have a coupling factor k.sub.c, which used to enhance the transconductance of the transistor pair, therefore can be used for power consumption reduction and phase noise minimalization.

The disclosure is directed to a frequency synthesizer circuit including digitally controlled oscillator (DCO) and an injection locked digitally controlled oscillator (ILD). The ILD outputs a signal with a frequency that is some fraction of the frequency of the DCO output signal and locked in phase to the DCO output signal. The frequency synthesizer circuit drives the ILD with the same modulation input signal that drives the DCO, with the modulation input signal scaled to account for any mismatch between the gains of the DCO and ILD. Driving the ILD with the same, scaled modulation signal as the main DCO minimizes the frequency offset between the DCO output signal and the divided natural oscillation frequency of the ILD. Minimizing the frequency offset makes the lock of the ILD more robust and reduces jitter contribution from the ILD.

A power transfer device includes an oscillator circuit of a DC/AC power converter responsive to an input DC signal and an oscillator enable signal to generate an AC signal. The oscillator circuit includes a first node, a second node, and a circuit coupled between the first node and the second node. The circuit includes a cross-coupled pair of devices. The oscillator circuit further includes a variable capacitor coupled between the first node and the second node. A capacitance of the variable capacitor is based on a digital control signal. A first frequency of a pseudo-differential signal on the first node and the second node is based on the capacitance. The power transfer device further includes a control circuit configured to periodically update the digital control signal. A second frequency of periodic updates to the digital control signal is different from the first frequency.

A differential Colpitts oscillator circuit is described which provides a larger tuning range, has better phase noise and uses less power than conventional differential Colpitts oscillator circuits. The circuit is characterized by a capacitive ladder in which only variable capacitor is used for tuning the circuit. In some embodiments, a variable capacitor can be used for fine tuning.

A differential Colpitts oscillator circuit is described which has center-tapped inductors which are cross-coupled with gates of second transistors of first and second transistor pairs which can reduce the minimum power supply voltage and the bias voltage for the circuit. In addition, a capacitive ladder can be implemented which also has the potential benefit of increased tuning range.

Techniques are described for using valley detection for supply voltage modulation in power amplifier circuits. Embodiments operate in context of a power amplifier circuit configured to be driven by a supply voltage generated by a supply modulator and to receive an amplitude-modulated (AM) signal at its input. The output of the power amplifier circuit can be fed to a valley detector that can detect a valley level corresponding to the bottom of the envelope of the AM signal. The detected valley level can be fed back to the supply modulator and compared to a constant reference. In response to the comparison, the supply modulator can vary the supply voltage to the power amplifier circuit in a manner that effectively tracking the envelope of the power amplifier circuit's output signal, thereby effectively seeking a flat valley for the output signal's envelope.

An integrated circuit comprising: a substrate; a configurable tank circuit on the substrate, the configurable tank circuit including: a first pair of inductive loops driven in parallel in each of a first configuration and a second configuration, each of the inductive loops in the first pair enclosing a corresponding capacitive element connected in parallel with that inductive loop; a second pair of inductive loops driven in parallel with the first pair of loops in the second configuration, the second pair of inductive loops undriven in the first configuration; and a switch arrangement that alternately places the configurable tank circuit into either of the first and second configurations; and an oscillation driver that drives the configurable tank circuit at a tunable resonance frequency.

A voltage controlled oscillator (VCO) circuit is disclosed. The VCO circuit comprises a VCO tuning circuit comprising a primary inductive coil. In some embodiments, the VCO tuning circuit is configured to generate a VCO output signal at a first resonance frequency. The VCO circuit further comprises a filter circuit comprising a secondary inductive coil. In some embodiments, the filter circuit is configured to resonate at a second, different, resonance frequency, in order to filter a noise associated with the VCO tuning circuit. In some embodiments, the primary inductive coil associated with the VCO tuning circuit and the secondary inductive coil associated with the filter circuit are concentrically arranged with respect to one another. Further, in some embodiments, the primary inductive coil associated with the VCO tuning circuit and the secondary inductive coil associated with the filter circuit are magnetically decoupled with respect to one another.

The invention relates to a resonator circuit, the resonator circuit comprising a transformer comprising a primary winding and a secondary winding, wherein the primary winding is inductively coupled with the secondary winding, a primary capacitor being connected to the primary winding, the primary capacitor and the primary winding forming a primary circuit, and a secondary capacitor being connected to the secondary winding, the secondary capacitor and the secondary winding forming a secondary circuit, wherein the resonator circuit has a common mode resonance frequency at an excitation of the primary circuit in a common mode, wherein the resonator circuit has a differential mode resonance frequency at an excitation of the primary circuit in a differential mode, and wherein the common mode resonance frequency is different from the differential mode resonance frequency.