69results about How to "Suppress spurs" patented technology

The invention discloses a soft base station system and process of synchronizing based on optical fiber zooming out. Presently, direct sending stations are used to expand the signal coverage in the mobile communication network, but noise level and low sensitivity are also brought in. The soft base station system based on optical fiber will transform the radio frequency signal directly coupled from the large capacity base station into optical signal through analog optical modulation, which will be transmitted to the soft base station via. the optical fiber, the soft base station will transform the optical signal into the electrical signal, which will radiate to the needed coverage via the service antenna. Apart from all the advantages resulted from using digital transmission and receiving machine, the soft base station has bee proved to increase system capacity, improve the network quality and reduce the occurrence of disconnection.

In a piezoelectric resonator, a portion of a thin film unit is supported by a substrate. A portion of the thin film unit acoustically isolated from the substrate includes a) a vibration unit and b) an additional film. The vibration unit includes a piezoelectric film sandwiched between a pair of electrodes. The piezoelectric film is overlapped with the pair of electrodes in plan view. The additional film is disposed on one of the piezoelectric film and the electrodes so as to extend along at least a portion of the periphery of the vibration unit. When x (MN·second/m³) denotes an acoustic impedance of the additional film defined by the square root of the product of the density and Young's modulus, A denotes the product of the density and the thickness of the additional film, B denotes the product of the densities and the thicknesses of the electrodes, and y=A/B, the following conditional expressions are satisfied:

In the range of 9.0≦x<44.0,

0.0092·x+0.88≦y<0.067·x+0.60   (1a)

In the range of 44.0≦x<79.0,

−0.0035·x+1.45≦y<0.015·x+2.9.   (1b)

A lamb wave type high frequency device includes: an interdigital transducer (IDT) electrode having an electrode finger interdigitated therein; a pair of reflectors having an electrode finger and being disposed at both sides of a propagation direction of a lamb wave excited by the IDT electrode; and a piezoelectric substrate on a surface of which the IDT electrode and the reflectors are disposed, wherein a pitch of the electrode finger of the IDT electrode and a pitch of the electrode finger of the reflectors are different from one another.

The invention relates to an X-band high-isolation radio frequency transceiver system and a channel consistency calibration method thereof, and relates to the technical field of radars, and the method comprises the steps: a calibration mode is set, and a calibration antenna receives an echo signal; the received echo signal is injected into a first-stage single-pole double-throw switch in the switch switching array network, then is subjected to low-noise amplification and then is input into a second-stage single-pole double-throw switch, and the signal is input into a down-conversion receiving channel; the down-conversion receiving channel outputs an intermediate frequency calibration signal after carrying out signal amplitude limiting processing, signal dynamic adjustment, spurious signal suppression, full temperature range gain compensation and phase consistency compensation. According to the invention, high channel isolation and switching of a plurality of working modes including a transceiving working mode, a calibration mode and the like are realized by adopting a switch assembly network. And meanwhile, the system also has the functions of sensitivity time control and manual gain control, and can realize large-dynamic-range echo signal processing and receiving under the condition of ensuring high isolation and multi-mode working conditions.

The invention discloses a phase locking loop frequency synthesizer. The phase locking loop frequency synthesizer comprises a frequency synthesis unit, a radio frequency switch, a phase frequency detector, a first loop filter, a voltage controlled oscillator, a preparatory frequency divider, a direct digital frequency synthesizer and a second loop filter, wherein an input end of the frequency synthesis unit is used to receive a first level reference frequency, the frequency synthesis unit performs synthesis treatment on the first level reference frequency and outputs frequencies, the number of the output frequencies is i, the radio frequency switch arbitrarily selects a frequency from the i frequencies, which is not in a multiple relationship with an output frequency, and uses the selected frequency as a second level reference frequency, the phase frequency detector performs phase comparison on the second level reference frequency and a feedback frequency after smoothing, and outputs phase detection voltage according to a comparison result, the first loop filter performs filtering processing on the phase detection voltage and outputs error voltage, the voltage controlled oscillator converts the error voltage into the output frequency, and the direct digital frequency synthesizer is used to perform fractional frequency division processing on another frequency output by the preparatory frequency divider and then output the feedback frequency. The phase locking loop frequency synthesizer uses switching of a plurality of reference sources, and can effectively restrain a stray phenomenon.

The invention relates to a millimeter wave sensor and an intelligent detector. The millimeter wave sensor includes a signal generator, a transceiver integrated chip, a bandpass filter, an amplifier, an A/D converter and a digital signal processor connected in sequence. Compared with the existing 24/77GHz millimeter wave sensor, the millimeter wave sensor has higher signal frequency, strong beam directivity, strong anti-interference ability, small size and light weight; in addition, it adopts the transceiver integrated chip based on SiGe process Compared with the sensor composed of discrete devices, it has the advantages of simple structure, small size and portability, convenient mass production, and low cost, which greatly improves the adaptability of the sensor and provides strong technical support for the increasingly complex information detection environment in the future.

The invention belongs to the wireless communication equipment field and discloses a wide-band high-speed frequency hopping frequency synthesizer and a working method thereof. The output end of a first oscillator is connected with the reference frequency input end of a phase-locked loop circuit, the input end of a first DDS and the input end of a second DDS; the output end of the phase-locked loop circuit is connected with the input end of an active loop filter; the output end of the active loop filter is connected with the input end of a voltage-controlled oscillator; the output end of the voltage-controlled oscillator is connected with the local frequency input end of an IQ modulator; the output end of the first DDS is connected with the input end of a first filter; the output end of the first filter is connected with the I-path signal input end of the IQ modulator; the output end of the second DDS is connected with the input end of a second filter; the output end of the second filter is connected with the Q-path signal input end of the IQ modulator; and the output end of the IQ modulator is connected with the radio frequency input end of the phase locked loop circuit.

A surface acoustic wave apparatus has a configuration by which the spurious of the higher-order transverse modes is suppressed and a SAW excitation intensity distribution is not changed in the propagation direction. The surface acoustic wave apparatus has at least one interdigital transducer, which is disposed such that a plurality of comb-shape electrodes respectively connected to common electrodes are interleaved, wherein a region with the plurality of interleaved comb-shape electrodes has a first overlapping region with a overlapping length constant over a whole area along a propagation direction of a surface acoustic wave and a second overlapping region formed on at least one side of the first overlapping region with a overlapping length weighted in the propagation direction of the surface acoustic wave, and wherein an overlapping-length weighting envelope curve in the second overlapping region has at least two changing points in the propagation direction of the surface acoustic wave.

The invention discloses a novel ultra-wideband multi-channel receiving system, and relates to the technical field of microwave communication. The system comprises a low-noise amplifier module, a down-conversion module and an intermediate frequency module which are connected in sequence; the low-noise amplifier module is connected with an antenna and outputs N-channel radio frequency signals; the down-conversion module comprises a switch filtering module and a first local oscillator power division network module; in each channel of the down-conversion module, the switch filtering module dividesthe radio-frequency signal into a predetermined low-frequency radio-frequency signal and a predetermined high-frequency radio-frequency signal, the predetermined low-frequency radio-frequency signalis directly transmitted to the intermediate-frequency module, and the predetermined high-frequency radio-frequency signal is transmitted to the intermediate-frequency module after being subjected to primary frequency mixing with the first local oscillation signal; the intermediate frequency module comprises a second local oscillator power division network module; the predetermined low-frequency radio-frequency signal and the primary frequency mixing radio-frequency signal are respectively and correspondingly accessed to each channel of the intermediate-frequency module and are subjected to secondary frequency mixing with the second local oscillation signal to output an intermediate-frequency signal, and mirror image interference and stray of the broadband receiving front end can be effectively suppressed through reasonable segmentation processing of the whole frequency band.

A surface acoustic wave apparatus has a configuration by which the spurious of the higher-order transverse modes is suppressed and a SAW excitation intensity distribution is not changed in the propagation direction. The surface acoustic wave apparatus has at least one interdigital transducer; a region with the plurality of interleaved comb-shaped electrodes is formed with two regions which are a first overlapping region and a second overlapping region with overlapping-lengths weighted along a propagation direction of a surface acoustic wave; the first overlapping region and the second overlapping region are in contact or overlapped in a direction vertical to the propagation direction of the surface acoustic wave; and in either the first or the second overlapping region, an overlapping-length weighting envelope curve has at least two or more changing points in the propagation direction of the surface acoustic wave.

The invention relates to broadband phase-locked frequency source equipment, belongs to the frequency source technology field, and is used to solve the problems of the prior art such as high phase noises, low output frequency, and high costs. The broadband phase-locked frequency source equipment comprises a forward path and a feedback path. The forward path comprises a phase discriminator, a loop filter, and a voltage-controlled oscillator. The feedback path comprises a harmonic diode mixing circuit. After the phase-locked loop is locked, the broadband phase-locked frequency source equipment isused to output a stable frequency signal, and is used for down conversion of a radio frequency signal to a relatively low medium frequency signal to improve a frequency synthesizer phase noise. The harmonic diode mixing circuit adopts even order harmonics of a local oscillation signal and the radio frequency signal for mixing, and when the output frequency is high, a large frequency doubling device is not required to be additionally disposed on a local oscillation input end, and therefore costs are saved. The equipment has advantages of simple operation, strong universality, low production costs, and strong applicability.

The invention relates to a micro-stepping ultra-wideband frequency agile frequency synthesizer with low spur and low phase noise. As shown in the drawings, the technologies of direct digital frequency synthesis and precise graded frequency synthesis and the real-time computing control of an FPGA (Field Programmable Gate Array) are adopted. A micro-stepping frequency agile control is implemented through the high performance computing of the FPGA and the function of a self-check table without the remote computing control of a radar system so that the computation of a control unit of the radar system and the control data transmission time and the transmission amount of the whole system are simplified and the frequency hopping speed and the real-time response capability of the frequency synthesizer are greatly increased and improved; through the technology of direct digital frequency synthesis, the frequency synthesizer has high frequency resolution so that the function of the frequency synthesizer for generating micro-stepping base band signals is achieved; and through the technology of precise partition frequency synthesis, which is implemented based on a great number of tests and precise computation, a narrow-band base frequency is divided for multiple times for frequency mixing so as to implement full coverage of ultra-wide frequency bands, so that spur and phase noise are effectively restrained from being worsen and the performances of high-speed frequency switching and high-frequency resolution of a DDS (Direct Digital Synthesis) technology for generating base frequencies are effectively retained. In the whole radar system, a universal frequency synthesizer platform capable of greatly shortening the frequency hopping time of the whole radar system and capable of being used as a radar is adopted; the control mode is simple and fast; and the index can fully meet the requirement of various new systems.

The invention discloses a miniature airborne up-converter which is composed of three parts of a local oscillator circuit, a frequency conversion channel circuit and a power control circuit. An output end of the local oscillator circuit and the power control circuit are connected with the frequency conversion channel circuit respectively. Manufacturing processes include steps of circuit design, circuit wiring, circuit electric fitting, final assembly and multi-channel quality test. Stray rejection ratio of local oscillator signals is improved greatly, and power dissipation of the whole machine is reduced, meanwhile, broadband phase discrimination is used, phase discrimination frequency is improved, rapid capture broadband is added, frequency agility time is increased, and problems of miscellaneous inhibition capacity, frequency agility time and the like of local oscillator signals are solved; a mixer with high compression is used as frequency spectrum flitting, secondary frequency conversion is used, needed broadband signals are produced through the secondary frequency conversion and output by amplification of filtering waves, stray is effectively restrained, and anti-interference capability is enhanced; and multi-channel quality test is used in the manufacturing process, checks are performed at all levels, and product yield and product quality are greatly improved.

To provide, in a frequency synthesizer including: a variable attenuator provided at a subsequent stage of a voltage controlled oscillator; a detector; and a control unit outputting a control voltage for adjusting an attenuation amount of the variable attenuator via a digital/analog converter in accordance with a detection voltage, a technology with which a spurious due to a change in an output of the digital/analog converter can be suppressed. A low-pass filter is provided between an output side of a digital/analog converter and a variable attenuator to cut a frequency component corresponding to an overshoot generated when an output of the digital/analog converter is changed. Further, a period of time from when a control unit outputs a control voltage to when it reads a signal level detected by a detector is set to a period of time longer than a time constant of the low-pass filter determined by a cut-off frequency of the low-pass filter so that no influence is exerted on an operation of automatically controlling the signal level.

The invention discloses a broadband X-band direct frequency synthesizer and a signal generation method. A crystal oscillator with high frequency accuracy and low phase noise generates a reference signal of a frequency standard generation circuit, a series of narrow dot frequencies at small frequency intervals and broad dot frequencies at large intervals are generated within a low frequency band, the narrow dot frequencies are inserted into the broad dot frequencies at the large intervals through up-conversion circuits and switching circuits to realize the function of frequency hopping at hundreds of dots, broadband signals are output through the up-conversion circuits, the switching circuits and frequency selection circuits, stray is effectively suppressed and the frequency synthesizer can realize quick frequency hopping. A designed miniature vibration isolation system can effectively reduce the influence of vibration on the phase noise. Compared with the other frequency synthesizers, the broadband X-band direct frequency synthesizer has the advantages that: an operating frequency band covers 30 percent of an X band; a stray suppression degree within a broadband range can reach more than 75dB; the phase noise is low, is -113 to -109dBc/Hz at the given frequency offset of 1KHz, and is lower than -100dBc/Hz at the given frequency offset of 1KHz; working temperature is -55 to +70 DEG C; and weight is light, and is lower than 3.7Kg.

The invention provides an electric circuit for restraining fractional stray of fractional phase locking loops. The electric circuit for restraining the fractional stray of the fractional phase locking loops comprises at least two levels of the fractional phase locking loops, wherein the front level fractional phase locking loop is connected with the back level fractional phase locking loop through a frequency divider, an output signal of the front level fractional phase locking loop is used as a reference input signal of the back level fractional phase locking loop after frequency division is performed on the output signal of the front level fractional phase locking loop by the frequency divider, and the front level fractional phase locking loop and the back level fractional phase locking loop are of the same structure. The method for restraining the fractional stray of the fractional phase locking loops includes the steps that fractional frequency division is performed by the frequency divider on an output signal of a voltage controlled oscillator, phase discrimination operation is performed by a phase discriminator on the input signal after the frequency division and the reference input signal, an output signal of the phase discriminator is sent into a loop filter, and the loop filter generates voltage controlled voltage of the voltage controlled oscillator. The electric circuit and the method for restraining the fractional stray of the fractional phase locking loops can directly change fractional stray frequency, are not influenced by nonlinear circuits of the phase discriminator, the frequency divider and the like in a circuit, and have good stray restraining effects. Additionally, the fractional stray frequency of the fractional phase locking loops is shifted out of the bandwidth of the fractional phase locking loops and filtered out by the loop filter, and therefore the purpose of restraining the fractional stray is achieved.

The invention discloses a wide-band vertical interdigital capacitor of a novel structure. The capacitor adopts low-temperature co-fired ceramic as a base and is designed to be of an eight-layer squarestructure; the capacitor is the vertical interdigital capacitor and is composed of eight sections of interdigitated fingers, that is to say, each layer of the eight-layer square structure is a section of interdigitated fingers, and all the sections of interdigitated fingers are located at the first to eighth layers respectively; a first port and a second port are formed in the centers of the twoopposite side surfaces of the interdigitated fingers respectively; vertical through holes are formed in the right ends of the first port and the second port; in the direction of the first port, open circuit ends of interdigital capacitor bodies at the second, fourth, sixth and eighth sections are connected through the corresponding vertical through holes; in the direction of the second port, opencircuit ends of interdigital capacitor bodies at the first, third, fifth and seventh sections are connected through the corresponding vertical through holes. The wide-band vertical interdigital capacitor (WBVIC) of the novel structure suppresses strays in frequency responses and increases the bandwidth by 100%. Meanwhile, the capacitance capacity is increased by 20%, but the Q value is not reduced.