A circuit device includes a control voltage input terminal to which a control voltage is inputted, an A/D conversion circuit A/D-converting the control voltage to generate control voltage data and A/D-converting a temperature detection voltage from a temperature sensor to generate temperature detection data, a processing circuit generating temperature compensation data of an oscillation frequency based on the temperature detection data and performing addition processing of the temperature compensation data and the control voltage data to generate frequency control data of the oscillation frequency, and an oscillation signal generation circuit generating an oscillation signal of the oscillation frequency set by the frequency control data, using the frequency control data and a resonator.

A wireless communication device is presented for use with a sensor. The wireless communication device includes: an antenna, a driver circuit and a bias circuit. The driver circuit is electrically coupled to the antenna and includes at least one pair of cross-coupled transistors. The bias circuit is electrically coupled to the driver circuit. In a transmit mode, the bias circuit biases the driver circuit with a first bias current. In response to the first bias current, the driver circuit oscillates the antenna. In a receive mode, the bias circuit biases the driver circuit with a second bias current, such that the first bias current differs from the second bias current. In response to the second bias current, the bias circuit amplifies a signal received by the antenna.

Variable frequency oscillators allowing wide tuning range and low phase noise is disclosed. In an illustrative embodiment, a first transistor has a first terminal (e.g. collector) connected to a reference voltage, and a second terminal (e.g. emitter) connected to a first terminal of a first current source and to ground. The first transistor further has a third terminal connected to a first inductor and to a first capacitor connected to the emitter of the first transistor and also to a second capacitor connected to ground. A second transistor is similarly constructed. In order to achieve a variable frequency oscillation between the emitters of the two transistors, a variable tank capacitor is connected between the inductors, forming a circuit connecting in series all passive components composing the LC tank, masking most of parasitic capacitances.

In accordance with an embodiment, a method of operating a voltage controlled oscillator (VCO) includes generating a first oscillating signal in a first VCO core and generating a second oscillating signal in a second VCO core, such that the first oscillating signal and the second oscillating signal have a same frequency and a fixed phase offset. The VCO includes the first VCO core and the second VCO core, and each VCO core includes a pair of transistors. The VCO also includes a transformer having a first winding coupled between control nodes of the pair of transistors of the first VCO core and a second winding coupled between control nodes of the pair of transistors of the second VCO core.

A differential Colpitts voltage-controlled oscillator according to example embodiments includes a feedback circuit constituting a Colpitts oscillator structure, a negative resistance circuit including a first negative resistance transistor and a second negative resistance transistor cross-coupled to each other and connected to the feedback circuit, a resonance circuit including a first inductor and a variable capacitor connected to both ends of the first inductor to generate differential output signals base on outputs of the feedback circuit, and a phase noise reduction circuit coupled to the feedback circuit to remove phase noise.

A method and a circuit for exciting a crystal oscillation circuit are disclosed herein. The crystal oscillation circuit comprising: charging, with a charging circuit, a voltage-controlled oscillator; providing, with the voltage-controlled oscillator, an exciting signal; blocking, with a direct current blocking capacitor, direct current from the voltage-controlled oscillator to the crystal oscillation circuit; and exciting, with the exciting signal, the crystal oscillation circuit. The circuit for exciting a crystal oscillation circuit, comprising: a charging circuit; a voltage-controlled oscillator coupled to the charging circuit and configured to provide an exciting signal to the crystal oscillation circuit; and a direct current blocking capacitor connected between the voltage-controlled oscillator and the crystal oscillation circuit and configured to block direct current from the voltage-controlled oscillator.

A synchronous oscillation circuit has multiple oscillators, a grounding unit and a common floating grounding unit. Each of the oscillators has a ground terminal. The grounding unit has a first terminal and a second terminal, wherein the second terminal is grounded. The common floating grounding unit is electrically connected between the ground terminals of the oscillators and the first terminal of the grounding unit. The oscillators are grounded through the common floating grounding unit and the grounding unit, so that the oscillators interfere with each other. When the oscillation signals generated by the oscillators reach a steady state, the oscillation frequencies of the oscillators are synchronized.

A method and apparatus for speeding up the start-up process of a crystal oscillator. The energy required for starting oscillations is inserted to the crystal by a stimulus in the form of a time-variant voltage or current pattern, either periodic or aperiodic. The stimulus is stopped after a pre-established period, then the oscillator continues to operate in its normal mode and completes the start-up process significantly faster, compared to a start-up process not comprising the above stimulus.

An integrated circuit device includes a substrate, a joining part provided on the substrate and joined to a vibrator, and a plurality of bonding pads provided on the substrate. The joining part includes an insulating protective film that covers a part of a surface of the substrate, and no insulating protective film is provided between the adjacent bonding pads.

An oscillator, including a resonance circuit, a cross coupled current source circuit, and a positive feedback circuit coupled between the current source circuit and the resonance circuit, where the resonance circuit is configured to generate a differential oscillation signal having a first oscillation frequency, the positive feedback circuit is configured to receive the differential oscillation signal, and amplify a gain of the differential oscillation signal to obtain a differential output oscillation signal, and the current source circuit is configured to provide an adjustable bias current for the resonance circuit and the positive feedback circuit. Since, the current source circuit provides the adjustable bias current for the positive feedback circuit and the resonance circuit, and forms a transconductance boosted (Gm-boosted) structure with the positive feedback circuit, the positive feedback circuit can amplify the gain of the received differential oscillation signal to obtain the differential output oscillation signal.