An oscillator operable in Class-C comprises at least one set of cross-coupled transistors. A threshold voltage of the transistors is controllable by having a bias voltage applied at back-gates of the transistors. The bias voltage thereby controls a conduction angle of the transistors to enable operation of the oscillator in Class-C. There is further provided a radio transceiver comprising such an oscillator, a method of operating such an oscillator, and a controller configured to operate such an oscillator.

A self-operating oscillator which increases an input DC voltage by a coefficient factor of 4 or more is provided. The self-operating oscillator includes a primary LC tank pair, a secondary LC tank pair, and a switch pair. The primary and the secondary LC tank provide a differential sinusoidal output voltage which corresponds to high amplitude, low phase noise and high purity.

A band-pass filter (BPF) includes a pair of coupled transformers including first through fourth conductive structures. The first conductive structure includes a first terminal and two first extending portions extending from the first terminal and configured as primary windings. The second conductive structure includes a second terminal and two second extending portions extending from the second terminal. A first via connects the third conductive structure to a first one of the two second extending portions, the third conductive structure and the first one of the two second extending portions thereby being configured as a first secondary winding. A second via connects the fourth conductive structure to a second one of the two second extending portions, the fourth conductive structure and the second one of the two second extending portions thereby being configured as a second secondary winding.

Inductor-capacitor oscillators and common mode resonators are provided. The inductor-capacitor oscillator includes a first transistor, a second transistor, an inductor, a first capacitor, a second capacitor, a first winding, and a second winding. The first transistor has a first terminal, a second terminal, and a third terminal. The second transistor has a fourth terminal, a fifth terminal and a sixth terminal. The first, second and third terminals are electrically connected to the fifth, fourth and sixth terminals, respectively. The first capacitor and the inductor are coupled between the first terminal and the fourth terminal. The second capacitor is coupled between the third terminal and a reference voltage. The first winding is coupled between the third terminal and the reference voltage. The second winding is coupled between the third terminal and the reference voltage. The first winding and the second winding are symmetric to each other.

An oscillator includes a resonator, sustaining circuit and detector circuit. The sustaining circuit receives a sense signal indicative of mechanically resonant motion of the resonator generates an amplified output signal in response. The detector circuit asserts, at a predetermined phase of the amplified output signal, one or more control signals that enable an offset-reducing operation with respect to the sustaining amplifier circuit.

An oscillator includes a first node having a first bias voltage, a second node having a second bias voltage, and a reference node having a reference voltage. A forward stage includes a first terminal coupled to an output terminal of the oscillator, and a second terminal coupled to one of the first node, the second node, or the reference node. A transformer-coupled band-pass filter (BPF) is coupled between the output terminal and a third terminal of the forward stage.

An oscillator generates a radio frequency (RF) output signal having high phase shift versus frequency characteristics close to a desired output frequency of the oscillator. The oscillator includes a resonator having a resonant frequency that is substantially the same as the desired output frequency of the oscillator, where the resonator provides a reflected signal; a resistor connected to one port of the resonator, another port of the resonator being connected to ground; an amplifier configured to receive the reflected signal from the resonator and to output an amplified reflected signal as the RF output signal; and a circulator having a first port connected to the resonator via the resistor, a second port connected to an input of the amplifier, and a third port connected to an output of the amplifier such that the amplified reflected signal is input back to the resonator.

A voltage controlled oscillator (VCO), a method of designing a voltage controlled oscillator, and a design structure comprising a semiconductor substrate including a voltage controlled oscillator are disclosed. In one embodiment, the VCO comprises an LC tank circuit for generating an oscillator output at an oscillator frequency, and an oscillator core including cross-coupled semiconductor devices to provide feedback to the tank circuit. The VCO further comprises a supply node, a tail node, and a noise by-pass circuit connected to the supply and tail nodes, in parallel with the tank circuit and the oscillator core. The by-pass circuit forms a low-impedance path at a frequency approximately twice the oscillator frequency to at least partially immunize the oscillator core from external noise and to reduce noise contribution from the cross-coupled semiconductor devices.

A clock oscillator includes with a pullable BAW oscillator to generate an output signal with a target frequency. The BAW oscillator is based on a BAW resonator and voltage-controlled variable load capacitance, responsive to a capacitance control signal to provide a selectable load capacitance. An oscillator driver (such as a differential negative gm transconductance amplifier), is coupled to the BAW oscillator to provide an oscillation drive signal. The BAW oscillator is responsive to the oscillation drive signal to generate the output signal with a frequency based on the selectable load capacitance. The oscillator driver can include a bandpass filter network with a resonance frequency substantially at the target frequency.

A voltage controlled oscillator (VCO) and buffer circuit includes a voltage controlled oscillator (VCO), a buffer circuit configured to receive a signal generated by the VCO, the buffer circuit comprising a first transistor having a parasitic gate-source capacitance (Cgs), and a second transistor coupled across the first transistor, wherein a gate of the first transistor is coupled to a drain and a source of the second transistor, and a gate of the second transistor is coupled to a source of the first transistor.