A voltage controlled oscillator includes a resonator and an amplifier. The resonator includes a capacitive element and an inductive element. The inductive element has a plurality of conductive segments forming a physical loop. The inductive element has electrical connections on the physical loop to the plurality of conductive segments forming at least one electrical loop disposed within an interior space formed by the physical loop. The amplifier has an input and an output, the input coupled to a first conductive segment forming a first impedance and the output coupled to a second conductive segment forming a second impedance.

A voltage controlled oscillator includes a first inductor; a first variable capacitance unit including a first variable capacitance element having a variable capacitance and a second variable capacitance element having a variable capacitance; a first node configured for application of a first voltage to the first variable capacitance unit; a cross-coupled unit including a first transistor and a second transistor, an output of the first transistor connected to an input of the second transistor; a current source configured to flow a current through the first inductor, the first transistor, and the second transistor; a second variable capacitance unit including a third variable capacitance element having a variable capacitance, and a fourth variable capacitance element having a variable capacitance; and a second node different from the first node configured for application of a second voltage to the second variable capacitance unit.

Apparatus and methods for adjusting a gain of an electronic oscillator, such as a voltage-controlled oscillator (VCO), are disclosed. In one aspect, an apparatus for compensating for VCO gain variations includes a charge pump controller. The charge pump controller can be configured to select a VCO gain model based on a comparison of a VCO gain indicator and a threshold value stored in a memory, obtain VCO gain model parameters from the memory corresponding to the selected VCO gain model, and compute a charge pump current control value using the VCO gain model parameters. The charge pump current control value can be used to compensate for VCO gain variations.

An accurate replica oscillator-based frequency tracking loop (FTL) is provided. The replica oscillator used in the FTL can be at a lower frequency and therefore can consume much lower power compared to a main oscillator, such as an injection locked oscillator (ILO). The proposed FTL accurately sets the free running frequency of an ILO across process, voltage and temperature (PVT). Techniques are also provided to compensate the gain and offset error between the replica oscillator and the ILO.

A quadrature voltage-controlled oscillator circuit with phase shift includes two voltage-controlled oscillators with the same structure, wherein the two voltage-controlled oscillators are connected to each other through input and output ports, and the two voltage-controlled oscillators respectively include a cross-coupled oscillating circuit, an injection locking circuit, a resonant circuit and a voltage-controlled current source circuit which are electrically connected to each other; and signals are injected through the injection locking circuit and coupled with the oscillating circuit, so as to output a quadrature signal. An oscillator is enabled to operate stably in one mode by means of a simple circuit structure, and a good phase shift can be provided for the resonant circuit in a lower frequency band; and meanwhile, a tuning range of the oscillator is improved without increasing phase noise.

Certain aspects of the present disclosure generally relate to a voltage-controlled oscillator (VCO) that is configurable (e.g., in a dynamic manner) in multiple modes of operation (e.g., low/high-band modes). The VCO may include a resonant circuit coupled to a plurality of switches that may be used to adjust current flow within one or more inductive elements of the resonant circuit. By adjusting the current flow within the inductive elements, an inductance of the resonant circuit may be adjusted, which in turn adjusts a band of the VCO.

A circuit for an oscillator with common-mode resonance includes a first oscillator circuit and a second oscillator circuit coupled to the first oscillator circuit. Each of the first oscillator circuit or the second oscillator circuit includes a tank circuit, a cross-coupled transistor pair, and one or more capacitors. The tank circuit is formed by coupling a first inductor with a pair of first capacitors. The cross-coupled transistor pair is coupled to the tank circuit, and one or more second capacitors are coupled to the tank circuit and the cross-coupled transistor pair. Each of the first oscillator circuit or the second oscillator circuit allows tuning of a respective common mode (CM) resonance frequency (F.sub.CM) to be at twice a respective differential resonance frequency (F.sub.D).

The present invention provides a digitally controlled oscillator device capable of realizing a reduction in DNL. The digitally controlled oscillator device includes, for example, an amplifier circuit block, coil elements and a plurality of unitary capacitor units coupled in parallel between oscillation output nodes. Each of the unitary capacitor units is provided with capacitive elements, and a switch which selects whether the capacitive elements should be allowed to contribute as set parameters for an oscillation frequency. The switch is driven by an on/off control line extending from a decoder circuit. The on/off control line is shielded between the oscillation output nodes by a shield section.

A voltage-controlled oscillator (VCO), includes a resonator circuit connected to receive an input voltage and having a first output node and a second output node; and at least one cross-coupled switching circuit portion, each cross-coupled switching circuit portion comprising a first transistor having a drain connected to the first output node and a second transistor having a drain connected to the second output node, the first transistor having a gate connected between the drain of the second transistor and the second output node and the second transistor having a gate connected between the drain of the first transistor and the first output node, each of the first and second transistors having a threshold voltage that is determined to be the highest threshold voltage available for the process used to create the VCO.

An apparatus includes an oscillation ring comprising N oscillators, where N is an even integer that is greater than 3, the N oscillators connected in series in a loop by N connection nodes, each oscillator of the N oscillators comprising a pair of cross-coupled inverting amplifiers. The apparatus also includes N inductors arranged in a star configuration such that each inductor of the N inductors connects to a corresponding connection node of the oscillation ring and a common connection node of the star configuration. The apparatus may also include N capacitor banks. Each of the N capacitor banks may include a plurality of activation switches for loading a corresponding oscillator with capacitance. A method includes providing the above apparatus and activating selected activation switches to adjust an oscillation frequency for the oscillation ring toward a desired value.