An oscillating device includes a first quartz crystal resonator, a driving circuit, a first waveform adjustment circuit, and at least two second quartz crystal resonators. The first quartz crystal resonator has a first resonant frequency. The driving circuit, coupled to the first quartz crystal resonator, drives the first quartz crystal resonator to generate a first oscillating signal having the first resonant frequency. The second quartz crystal resonators, coupled in parallel and coupled to the driving circuit and the first quartz crystal resonator, have a second resonant frequency and receive and rectify the first oscillating signal to generate a second oscillating signal having the second resonant frequency. The first waveform adjustment circuit, coupled to the second quartz crystal resonators, receives the second oscillating signal and adjusts the second oscillating signal to generate a first waveform adjustment signal.

An oscillating device includes a first quartz crystal resonator, a driving circuit, a first waveform adjustment circuit, and at least two second quartz crystal resonators. The first quartz crystal resonator has a first resonant frequency. The driving circuit, coupled to the first quartz crystal resonator, drives the first quartz crystal resonator to generate a first oscillating signal having the first resonant frequency. The second quartz crystal resonators, coupled in parallel and coupled to the driving circuit and the first quartz crystal resonator, have a second resonant frequency and receive and rectify the first oscillating signal to generate a second oscillating signal having the second resonant frequency. The first waveform adjustment circuit, coupled to the second quartz crystal resonators, receives the second oscillating signal and adjusts the second oscillating signal to generate a first waveform adjustment signal.

An oscillator circuit includes a first BAW oscillator, a first coupling stage, a second BAW oscillator, and a second coupling stage. The first BAW oscillator is configured to generate a first output signal at a frequency. The first coupling stage is coupled to the first BAW oscillator, and is configured to amplify the first output signal. The second BAW oscillator is coupled to the first coupling stage, and is configured to generate a second output signal at the frequency. The second output signal differs in phase from the first output signal. The second coupling stage is coupled to the first BAW oscillator and the second BAW oscillator, and is configured to amplify the second output signal and drive the first BAW oscillator.

A frequency doubler (tripler, or quadrupler) employs current re-use coupled oscillator technique to enhance phase noise without increasing current consumption. Frequency doubler uses coupling between two oscillators running at different frequencies; a first oscillator is running at the target frequency and a second oscillator is running at half the frequency. The coupling between the two oscillators is via a transformer having a primary transformer coil and a secondary transformer coil. The first oscillator comprises a differential inductor, coarse/fine tuning capacitor arrays, and an n-type trans-conductor (GM). A virtual ground node of the n-type GM is coupled to one side of the primary transformer coil and the other side of the primary coil is coupled to the center tap of the secondary coil. The second oscillator comprises the secondary coil, coarse/fine tuning capacitor arrays, n-type GM, frequency tracking loop (FTL) and 2.sup.nd-harmonic LC filter network.

A frequency doubler (tripler, or quadrupler) employs current re-use coupled oscillator technique to enhance phase noise without increasing current consumption. Frequency doubler uses coupling between two oscillators running at different frequencies; a first oscillator is running at the target frequency and a second oscillator is running at half the frequency. The coupling between the two oscillators is via a transformer having a primary transformer coil and a secondary transformer coil. The first oscillator comprises a differential inductor, coarse/fine tuning capacitor arrays, and an n-type trans-conductor (GM). A virtual ground node of the n-type GM is coupled to one side of the primary transformer coil and the other side of the primary coil is coupled to the center tap of the secondary coil. The second oscillator comprises the secondary coil, coarse/fine tuning capacitor arrays, n-type GM, frequency tracking loop (FTL) and 2.sup.nd-harmonic LC filter network.

A frequency doubler is provided that filters an input signal to form I and Q components responsive to a tuning signal. A single sideband mixer mixes the I and Q components with I and Q components of a local oscillator signal to form an output signal having a frequency of twice the frequency of the input signal.

A substance detection system and a substance detection method are provided. The temperature identifying portion identifies a surface temperature of the quartz substrate, based on a difference between a deviation of the fundamental wave frequency from at least any predetermined reference fundamental wave frequency of the reference crystal resonator and the detecting crystal resonator and a deviation of the third harmonic frequency from a predetermined reference third harmonic frequency. The substance identifying portion identifies a temperature at which a contaminant attached to the detecting crystal resonator is desorbed from the detecting crystal resonator to identify the contaminant based on the temperature at which the contaminant is desorbed. The temperature is identified based on a difference between the fundamental wave frequency of the reference crystal resonator and the fundamental wave frequency of the detecting crystal resonator measured by the frequency measuring portion and the temperature identified by the temperature identifying portion.

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.

A sensing sensor includes an oscillator circuit, a base, a connection portion, and a temperature changing unit. The oscillator circuit oscillates the piezoelectric resonator. The base includes a base main body in which a depressed portion is provided and a lid portion at one side, supports the piezoelectric resonator at another side, and is for taking the oscillation frequency to an outside of the sensing sensor. The depressed portion houses the oscillator circuit. The lid portion covers the depressed portion. The connection portion is disposed at the one side of the base and connected to a cooling mechanism for cooling the base from the one side. The temperature changing unit is interposed between the piezoelectric resonator and the base, so as to cool and heat the piezoelectric resonator and transfer a heat radiated for cooling the piezoelectric resonator from the other side of the base to the one side.