64results 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 pertains to the field of the design technology of wireless communication system transceiver chip. The characteristics reside in that: the novel back-to-back series connected type MOS varactor adopting the digital signal control forms the main hypercap part of the numerical controlled LC oscillator, and the phase noise converted from the amplitude noise from the oscillator is reduced, and the restraining ability of the oscillator to the noise from the current source is improved, thus, the phase noise of the output signal of the oscillator is finally reduced. The method in the present invention, comparing with the prior method, can improve the performance of the on-piece CMOS oscillator and reduce the power consumption of the oscillator effectively, thus, the method is useful to the reduction of the manufacturing cost and power consumption of the receiver.

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.

The invention discloses a C-waveband frequency comprehensive generator with low phase noise and wide frequency agility. The generator comprises a 100 MHz of constant-temperature crystal oscillator, a power divider, a frequency tripler, a P-waveband phase locked loop, a C-waveband sampling phase locked medium oscillator, a mixer, a filter, a programmable logic device, a digital frequency direct synthesizer and a frequency divider. The generator disclosed by the invention has the characteristics that: the digital frequency synthesizer (DDS) is rationally utilized; the radar emission waveform iseasy to generate; the digital phase locked circuit is simple; the frequency change is convenient; the remote end of the sampling phase locked medium oscillator has excellent phase noise; the shortcomings are mutually made up; the circuit structure is simple; the phase noise is good; the radar waveform is convenient to change; furthermore, the frequency agility is rapid to carry out.

A voltage-controlled oscillator includes (i) a first variable-capacity element, (ii) a resonance circuit whose resonance frequency changes in accordance with a control voltage applied to the first variable-capacity element, (iii) a second variable-capacity element connected in parallel with the first variable-capacity element, (iv) resonance frequency range switching means which switches the variation range of the resonance frequency of the resonance circuit by switching the capacity of the second variable-capacity element, and (v) a resonance frequency correction circuit which corrects the resonance frequency in such a manner as to prevent the ratio between resonance frequencies before and after the switching of the variation range from depending on the control voltage.

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 differential voltage controlled oscillator (VCO) employed in a frequency synthesizer used as a local oscillator of a wireless communication on-chip transmitter / receiver is provided. More particularly, a differential current negative feedback VCO equipped with a current-current negative feedback circuit that suppresses low- and high-frequency noise is provided.A differential current negative feedback VCO includes a resonator determining oscillation frequency, and an oscillator generating negative resistance. In the oscillator of the differential current negative feedback VCO, transistors Q1 and Q2 form a cross-coupled pair, and negative resistance is generated by positive feedback of the cross-coupled pair. And, transistors Q1 and Q3 together with an emitter resistor and a capacitor form a current negative feedback part, and transistors Q2 and Q4 together with an emitter resistor and a capacitor form another current negative feedback part which is disposed opposite to a resonator. Thus, the VCO operates differentially.In the oscillator of the differential current negative feedback VCO, emitter noise currents generated by base noise voltages of Q1 and Q2 induced by low- and high-frequency noise sources in the bases of Q1 and Q2 are sampled by emitter resistors, amplified through bases of Q3 and Q4, and thus return to the bases of the Q1 and Q2 and suppress the base noise voltages. Measurement of the phase noise of the differential current negative feedback VCO reveals a phase noise reduction of approximately 25 dB compared to a conventional differential VCO.

The invention discloses a frequency synthesizer for driving phase-locked loop after up-converting DDS. The frequency synthesizer for driving phase-locked loop after up-converting DDS comprises a DDS circuit (5) and a phase-locked loop circuit (7); the output end of a highly stable crystal oscillator (1) is connected with the input end of a first 3 dB power divider (2); the output end of the first 3 dB power divider (2) is connected respectively with the input ends of a first direct frequency multiplier circuit (3) and a second direct frequency multiplier circuit (4); the output ends of the first direct frequency multiplier circuit (3) and a FPGA control circuit (8) are respectively connected with the input end of the DDS circuit (5); the output ends of the second direct frequency multiplier circuit (4) and the DDS circuit (5) are respectively connected with the input end of a frequency mixing filter circuit (6); and the output end of the frequency mixing filter (6) is connected with the input end of the phase-locked loop circuit (7). The frequency synthesizer for driving phase-locked loop after up-converting DDS solves the problems of the prior art such as high stray, high phase noise, large physical dimension and high power consumption exceeding standard, due to directly driving the phase-locked loop by the DDS or driving the phase-locked loop after up-converting and dividing the DDS.

In a quadrature voltage controlled oscillator, a first oscillator includes a first resonant circuit for generating a preset first resonant frequency and a first pair of cross-coupled transistors for supplying energy to the first resonant frequency to generate first and second signals having a phase difference of 180°. A second oscillator includes a second resonant circuit for generating a preset second resonant frequency and a second pair of cross-coupled transistors for generating third and fourth signals for supplying energy to the second resonant frequency having a phase difference of 180°. A first current source is connected between a first common node of the first cross-coupled transistor pair and a ground. A second current source is connected between a second common node of the second cross-coupled transistor pair and the ground. A differential load is connected between a third common node of the first and second current sources and the ground.

In a phase locked loop arrangement of a frequency synthesiser, a signal outputted from a voltage controlled oscillator is locked to a reference oscillator. A phase detector is arranged so that the frequency of the reference oscillator is a multiple of the frequency of the voltage controlled oscillator, which significantly reduces the phase noise emitted by the voltage controlled oscillator.

Provided is a voltage controlled oscillator to which a switching bias technique is applied so as to lower flicker noise of a bias circuit and enhance phase noise characteristics, thereby reducing the overall chip area to make it possible to achieve integration. A common mode voltage applied to the bias circuit is negatively fed back to an oscillation waveform. Therefore, it is possible to stabilize the magnitude of the oscillation waveform of the voltage controlled oscillator with respect to a change in an external condition.

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.

Disclosed is a quadrature VCO (voltage controlled oscillator) which comprises a first delay cell including a first switching transistor and a second switching transistor, the first delay cell outputting first and second in-phase signals with different phases; and a second delay cell including a third switching transistor and a fourth switching transistor, the second delay cell outputting first and second quadrature-phase signals with different phases. The first and second quadrature-phase signals are applied to back gates of the first and second switching transistors, and the first and second in-phase signals are applied to back gates of the fourth and third switching transistors.

A MEMS oscillator having a feedback-type oscillation circuit including a MEMS resonator and an amplifier, a voltage control unit operable to control a bias voltage applied to an oscillating member of the MEMS resonator, and an auto gain control unit which receives an output from the amplifier and, based on a level of the output, to output an amplitude control signal for controlling a gain of the amplifier to the amplifier such that the level of the output from the amplifier comes to be a predetermined level, wherein the voltage control unit controls the bias voltage applied to the oscillating member based on an operating temperature of the MEMS resonator such that a peak gain of the MEMS resonator comes to have a predetermined value regardless of the operating temperature, and the voltage control unit derives the operating temperature of the MEMS resonator by monitoring the amplitude control signal.

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 invention relates to a double-loop frequency synthesizer and a phase noise analyzing method. The double-loop frequency synthesizer comprises a crude regulation loop and a fine regulation loop, wherein the crude regulation loop comprises a frequency and phase discriminator, a charge pump, a filtration capacitor, a voltage-controlled oscillator and a programmable divider sequentially connected with each other; and the fine regulation loop comprises a frequency and phase discriminator, a charge pump, a loop filter, a voltage-controlled oscillator and a programmable divider sequentially connected with each other; and the frequency and phase discriminator, the voltage-controlled oscillator, the programmable divider and the crude regulation loop are shared. The phase noise analyzing method of the double-loop frequency synthesizer obtains the noise transfer function of each noise source in the double-loop frequency synthesizer by obtaining the transfer function of a crude regulation branch, a fine regulation branch and a common loop. The phase noise of the double-loop frequency synthesizer is lower than that of a single-loop frequency synthesizer under the same condition.

Disclosed is a dual-band voltage-controlled oscillator using bias switching and output-buffer multiplexing. The dual-band voltage-controlled oscillator includes a power supply unit for supplying a source voltage; plural voltage-controlled oscillation units for outputting different oscillation frequencies according to controls of a certain tuning voltage; plural bias units for generating driving voltages for driving the voltage-controlled oscillation units and supplying the driving voltages to the voltage-controlled oscillation units; and plural buffers for selectively outputting oscillation frequencies of the plural voltage-controlled oscillation units. The present invention implements the dual-band voltage-controlled oscillator through bias switching and output-buffer multiplexing, which brings an advantage of elimination of interference between output frequencies to enhance phase noise characteristics.

The present invention concerns a differential oscillator device, comprising resonant electronic means, capable to provide on at least two terminals at least one oscillating signal VOUT, which comprises a generator electronic means capable to supply at least one power supply pulsed signal to said resonant electronic means in phase relation with said at least one oscillating signal VOUT. The present invention further concerns a process of supplying pulsed power to such a differential oscillator device.

To provide a voltage controlled oscillator having small size and capable of obtaining a low phase noise characteristic over a large span of adjustable range of frequency. A quartz crystal having a characteristic (dielectric loss tangent: tan δ) better than that of fluorocarbon resin, LTCC or the like conventionally used as a substrate of a resonance part 1, and on which a fine pattern of metal film can be formed through a photolithography method, is used as a quartz-crystal substrate 10, and a conductive line is formed on the quartz-crystal substrate 10 to form an inductance element 11 in the resonance part 1. Accordingly, since the resonance part 1 having a high Q value can be formed, it is possible to obtain a voltage controlled oscillator having small size and low loss over a wide frequency band.

An oven controlled crystal oscillator includes a crystal oscillator, a temperature control circuit, and a control integrated circuit. The crystal oscillator includes a crystal resonator and an oscillator circuit. The temperature control circuit includes a heater resistor, a thermistor, a first resistor, a second resistor, a third resistor, a differential amplifier, a thermosensor, and a fourth resistor. The thermosensor is disposed in parallel to the first resistor. The thermosensor has one end to which the supply voltage is supplied. The fourth resistor has one end connected to another end of the thermosensor and another end that is grounded. The control integrated circuit includes a digital variable resistor and a controller. The digital variable resistor is connected to the thermosensor in parallel. The controller adjusts a resistance value of the digital variable resistor based on a digital control signal input from outside.

A low-noise voltage controlled oscillator is provided, to improve a phase noise characteristic and widen a frequency variable range. The low-noise voltage controlled oscillator is configured so that an oscillation element and a capacitor 2 are connected in series between a collector C and an emitter E of a transistor 1, capacitors 3 and 4 are connected in series between the collector C and the emitter E, an electrical potential between the capacitors 3 and 4 is applied to a base B of the transistor 1; a one-port circuit 6 is provided between the collector C and the capacitor 4; and a capacitor for correction 5 is connected in parallel with the capacitors 3 and 4. The one-port circuit 6 includes a tuned circuit provided with a variable capacitor adjusting a capacity thereof smaller and an inductor adjusting a value of inductance larger so as to set a value of impedance relatively large.

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 a transconductance linear broadband LC type voltage-controlled oscillator and an adjustable capacitor array circuit. The transconductance linear broadband LC type voltage-controlled oscillator comprises an LC oscillation circuit and a first adjustable capacitor array circuit; the LC oscillation circuit is characterized by comprising a first PMOS transistor, a second PMOS transistor, a first three-end differential inductor and a biasing circuit; the grid electrode of the first PMOS transistor is connected with the drain electrode of the second PMOS transistor through a first AC coupling capacitor; the grid electrode of the second PMOS transistor is connected with the drain electrode of the first PMOS transistor through a second AC coupling capacitor; the two symmetrical ends of the first three-end differential inductor are separately connected with the grid electrode of the first PMOS transistor and the grid electrode of the second PMOS transistor; the center tapend of the first three-end differential inductor is connected with the biasing circuit; and the first adjustable capacitor array circuit is connected in parallel with the two symmetrical ends of thefirst three-end differential inductor. The transconductance linear broadband LC type voltage-controlled oscillator and the adjustable capacitor array circuit can be widely applied to various high-frequency local oscillation phase-locked loop systems.

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.

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.