An inductor-capacitor (LC) oscillator with an embedded second harmonic filter and an associated dual core oscillator are provided. The LC oscillator includes a first transistor, a second transistor, a first part-one inductor, a second part-one inductor, a part-one capacitor, a part-two inductor and at least one part-two capacitor. A first end of the first part-one inductor and a first end of the second part-one inductor are coupled to gate terminals of the second transistor and the first transistor, respectively. The part-one capacitor is coupled between the first end of the first part-one inductor and the first end of the second part-one inductor. The part-two inductor is coupled between a second end of the first part-one inductor and a second end of the second part-one inductor. The at least one part-two capacitor is coupled to drain terminals of the first transistor and the second transistor.

An inductor-capacitor (LC) oscillator with an embedded second harmonic filter and an associated dual core oscillator are provided. The LC oscillator includes a first transistor, a second transistor, a first part-one inductor, a second part-one inductor, a part-one capacitor, a part-two inductor and at least one part-two capacitor. A first end of the first part-one inductor and a first end of the second part-one inductor are coupled to gate terminals of the second transistor and the first transistor, respectively. The part-one capacitor is coupled between the first end of the first part-one inductor and the first end of the second part-one inductor. The part-two inductor is coupled between a second end of the first part-one inductor and a second end of the second part-one inductor. The at least one part-two capacitor is coupled to drain terminals of the first transistor and the second transistor.

An apparatus is disclosed for implementing multi-mode oscillation circuitry with stepping control. In an example aspect, the multi-mode oscillation circuitry comprises a resonator coupled to a first oscillator and a second oscillator. The multi-mode oscillation circuitry is configured to selectively be in a first configuration with the first oscillator in an active state and the second oscillator in an inactive state or a second configuration with the first oscillator in the inactive state and the second oscillator in the active state. The apparatus also includes a step-control circuit coupled to the multi-mode oscillation circuitry. The step-control circuit is configured to cause the first oscillator to switch from the inactive state to the active state and incrementally increase a first gain of the first oscillator based on the first oscillator being in the active state to enable the multi-mode oscillation circuitry to transition from the second configuration to the first configuration.

Methods and systems for reducing phase noise in a voltage controlled oscillator (VCO) are described. In an example, a first transistor, a second transistor, a third transistor, and a fourth transistor, can be provided. A transformer can be used to decouple drain terminals and gate terminals of the first, second, third, and fourth transistors. An oscillation amplitude of the VCO can be increased by providing a first bias voltage to the transformer to adjust gate bias voltages of the first and second transistors. The oscillation amplitude of the VCO can also be increased by providing a second bias voltage to the transformer to adjust gate bias voltages of the third and the fourth transistors.

The present disclosure relates to an oscillator device (15) comprising an amplifier unit (16) and a tunable waveguide resonator (1) which in turn comprises a rectangular waveguide part (2) having electrically conducting inner walls (3) and a first waveguide port (4). The amplifier unit (16) is arranged to be electrically connected to the waveguide resonator (1) via the first waveguide port (4) by means of a first connector (17). The waveguide resonator (1) comprises at least one tuning element (6) positioned within the waveguide part (2), wherein each tuning element (6) comprises an electrically conducting body (7) and a holding rod (8a, 8b). The holding rod (8a, 8b) is attached to the electrically conducting body (7) and is movable from the outside of the waveguide resonator (1) such that the electrically conducting body (7) can be moved between a plurality of positions within the waveguide part (2) by means of the holding rod (8a, 8b).

In some embodiments, a differential oscillator includes a differential circuit coupled between a first output node and a second output node and a transformer-coupled band-pass filter (BPF). The transformer-coupled BPF is coupled between the first output node and the second output node and includes a coupling device and a transformer. The coupling device is coupled between the first output node and the second output node. The transformer includes a first winding coupled between the first output node and a voltage node and a second winding coupled between the second output node and the voltage node.

Oscillators and methods for realignment of an oscillator are provided. An oscillator includes an inductor having first and second terminals and a capacitor electrically coupled in parallel to the inductor at the first and second terminals. A first transistor of a first conductivity type is electrically coupled to the first terminal and a voltage source. The first transistor includes a gate configured to receive a first realignment signal. When the first realignment signal is in a realignment state, the first transistor is turned on and a voltage of the first terminal is increased from a low level to a high level in order to align a phase of a waveform of the oscillator.

An ultra-low noise crystal oscillator uses two crystal unit; an oscillation element of an oscillation circuit section and a crystal filter of a subsequent filter section. A Butler circuit in which the capacitors (C1, C2) and the inductor (L) connected in series is connected in parallel to the oscillator circuit section. This is the crystal oscillator that simplifies the manufacturing process, improves the manufacturing quality, and has good floor noise characteristics.

An ultra-low noise crystal oscillator uses two crystal unit; an oscillation element of an oscillation circuit section and a crystal filter of a subsequent filter section. A Butler circuit in which the capacitors (C1, C2) and the inductor (L) connected in series is connected in parallel to the oscillator circuit section. This is the crystal oscillator that simplifies the manufacturing process, improves the manufacturing quality, and has good floor noise characteristics.

A frequency synthesizer (230) is described that includes: a voltage controlled oscillator, VCO (330); a VCO bias circuit (370), operably coupled to the VCO (330) and configured to provide a controllable bias current (384) of the VCO (330); a temperature sensor (372) located in the frequency synthesizer (230) and configured to determine an operating temperature of the frequency synthesizer (230); an analog-to-digital converter, ADC (376), operably coupled to the temperature sensor (372) and configured to provide a digital representation (378) of the determined operating temperature; and a bias control circuit (380) operably coupled to the ADC (376) and the VCO bias circuit (370) and configured to provide a bias control signal (382) to the VCO bias circuit (370) based on the determined operating temperature of the frequency synthesizer (230). The VCO bias circuit (370) is configured to adjust the controllable bias current (384) applied to the VCO based on the bias control signal (382). The frequency synthesizer (230) includes a digitally-controlled bias current adjustment method for a wideband low noise VCO, for example using idle time intervals of signal transitions.