63results about How to "Good phase noise characteristics" patented technology

The invention discloses an optoelectronic oscillator with tunable broadband frequency, which is characterized in that a photon microwave filter is composed of an optical modulator, a high-fineness Fabry-Perot etalon and two fiber couplers and is applied to the optoelectronic oscillator. By tuning wavelength of laser light sources, the filtering peak of the photon microwave filter can be tuned; meanwhile, a microwave phase shifter is used cooperatively, thus continuous large-scale tuning of the optoelectronic oscillator can be realized finally.

The present invention relates to a variable oscillation frequency resonance circuit and voltage controlled oscillator using the same, which includes an inductance element, frequency varying means, and oscillation band varying means. The oscillation band varying means is provided with one or more capacitance element pairs and one or more differential switching element pairs each being arranged between capacitance elements of each of the capacitance element pairs, with differential switching elements of each of the differential switching element pairs being arranged in parallel with each other, to allow a corresponding capacitance element pair to be connected to the inductance element in response to second control signals.

Provided is an oscillator using an MEMS resonator, which can reduce an influence of noise of a TIA and improve phase noise characteristics of an oscillator output. The oscillator includes an MEMS resonator, a TIA, a buffer amplifier, and a current/voltage converter that couples, by electromagnetic induction, with a wiring line via which an output of the MEMS resonator is fed to the TIA, so as to convert a current flowing in the wiring line to a voltage and output the voltage to the buffer amplifier. Thus, the oscillator output is extracted from the current/voltage converter. Further, the current/voltage converter is provided in the form of an oscillation output coil provided so as to surround the wiring line in a noncontact manner, in which oscillation output coil one end is connected to ground and the other end is connected to the buffer amplifier.

A VCO include a resonance tank circuit(A) and an amplification circuit(B) which oscillates and is amplified at a resonance frequency of the resonance tank circuit(A). The resonance tank circuit(A) is provided with a capacity band switching circuit(D) for varying an oscillation frequency band, and a current band switching circuit(E) for feeding an appropriate current, corresponding to each oscillation frequency band, to the amplification circuit(B). This allows expansion of the oscillation frequency variable range as well as realization of a favorable phase noise characteristic in a broad band by optimization of a current in each frequency band.

A phase-locked loop (PLL) circuit including a voltage-controlled oscillator (VCO) with a variable gain is provided. A phase frequency detector (PFD) detects a phase difference between a reference signal and a PLL feedback signal. A charge pump and a loop filter sequentially process an output signal of the PFD. A VCO has different gains according to a mode transition. A control voltage applied to the VCO is selected from an output signal of the loop filter and an additional control signal according to the mode transition.

This invention discloses a method for compensating crystal frequency temperature property based on temperature sensing material stress, which contains using vacuum plating method to plate temperature sensing double-metal material on the crystal chip or electrode of crystal resonator which can compensate the frequency variation due to temperature of crystal. Said method can make the frequency temperature property of crystal reach positive and negative 0.2ppm and simply the current circuit of temperature compensation with small volume and low cost.

The present invention relates to a distributed oscillator, and more particularly, to a high frequency distributed oscillator using coupled transmission lines. According to the present invention, coupled transmission lines capable of increasing the frequency selectivity are used as transmission lines. Signal interference occurs among the coupled transmission lines because of mutual approximation. The coupled transmission lines serve as a filter due to the signal interference. A phase noise characteristic can be thus increased.

The invention discloses an X waveband fine stepped frequency synthesizer generating method and system, wherein the method comprises the following steps: (1) generating a frequency mixing local oscillator signal; (2) generating a Direct Digital Synthesis DDS baseband signal; (3) performing frequency mixing on the frequency mixing local oscillator signal and the DDS baseband signal to form frequencysynthesizer signal output. The method in the invention is optimized and improved based on the traditional frequency synthetic technology; a circuit structure of the DDS in combination with frequencymultiplication frequency mixing is designed, thereby realizing generation of the frequency synthesizer signal that operates at the X waveband with the frequency step reaching 1 KHz and taking the excellent phase noise characteristic and the good spurious suppression capability into account as well; the generation difficulty of the high-band and fine frequency stepped frequency synthesizer signalsis solved in engineering; and local oscillator signals with good purity and high quality can be provided for frequency conversion channels.

The invention discloses an inductance-capacitance voltage-controlled oscillator, which comprises negative resistance P-channel metal oxide semiconductor (PMOS) transistors M1 and M2, negative resistance N-channel metal oxide semiconductor (NMOS) transistors M3 and M4, an inductor L and an adjustable capacitor C, and is characterized in that: the inductance-capacitance voltage-controlled oscillator comprises a common-mode control circuit for controlling common mode points of oscillating signals VOSCP and VOSCN, wherein the common-mode control circuit comprises phase inverters U1 and U2, a compensating capacitor CC, a tail-current NMOS transistor MN, a tail-current PMOS transistor MP and a monitoring circuit. Compared with the traditional inductance-capacitance voltage-controlled oscillator, the common-mode controlled inductance-capacitance voltage-controlled oscillator successfully solves the problem that the output clock duty deviates 50 percent due to offset of negative resistance tube voltage-current transfer characteristics; therefore, good phase noise characteristics of a phase locked loop can be guaranteed.