37results about How to "High center frequency" patented technology

New methods of ultrasound imaging are presented that provide images with reduced reverberation noise and images of nonlinear scattering and propagation parameters of the object, and estimation of corrections for wave front aberrations produced by spatial variations in the ultrasound propagation velocity. The methods are based on processing of the received signal from transmitted dual frequency band ultrasound pulse complexes with overlapping high and low frequency pulses. The high frequency pulse is used for the image reconstruction and the low frequency pulse is used to manipulate the nonlinear scattering and/or propagation properties of the high frequency pulse. A 1^st method uses the scattered signal from a single dual band pulse complex for filtering in the fast time (depth time) to provide a signal with suppression of reverberation noise and with 1^st harmonic sensitivity and increased spatial resolution. In other methods two or more dual band pulse complexes are transmitted where the frequency and/or the phase and/or the amplitude of the low frequency pulse vary for each transmitted pulse complex. Through filtering in the pulse number coordinate and corrections of nonlinear propagation delays and optionally also amplitudes, a linear back scattering signal with suppressed pulse reverberation noise, a nonlinear back scattering signal, and quantitative nonlinear scattering and forward propagation parameters are extracted. The reverberation suppressed signals are further useful for estimation of corrections of wave front aberrations, and especially useful with broad transmit beams for multiple parallel receive beams. Approximate estimates of aberration corrections are given. The nonlinear signal is useful for imaging of differences in tissue properties, such as micro-calcifications, in-growth of fibrous tissue or foam cells, or micro gas bubbles as found with decompression or injected as ultrasound contrast agent. The methods are also useful with transmission imaging for generating the measured data for tomography and diffraction tomography image reconstructions.

The invention relates to the field of surface acoustic wave device manufacturing, and specifically relates to a structure of a flexible surface acoustic wave device resistant to high temperature and a manufacturing method thereof. The structure sequentially comprises, from bottom to top, a bottom protective layer, a flexible alloy substrate, a buffer layer, a piezoelectric film, an interdigital electrode, and a top protective layer. The flexible alloy substrate is made of high-temperature flexible alloy strips. The buffer layer and the bottom protective layer are amorphous oxide films. The piezoelectric film is an aluminum nitride film. The interdigital electrode is made of gold. The top protective layer is an aluminum nitride film. The method comprises the steps of preprocessing the flexible alloy substrate, preparing the amorphous oxide films by a chemical solution dip-coating method, preparing the piezoelectric film and the interdigital electrode, and finally, preparing the top protective layer. The flexible surface acoustic wave device has the advantages of being resistant to high temperature, good in flexible characteristic, light, capable of working in a complex curved surface environment, and low in cost.

An acoustic surface wave filter comprises a base (2) and a cap (9), a filter pattern layer is arranged on the base (2), and the filter pattern layer comprises a sending interdigital transducer (3), a receiving interdigital transducer (4), ground wires (7), a signal input port (5) and a signal output port (6); the ground wires (7) comprise a first ground wire (71) connected with the sending interdigital transducer (3) and a second ground wire (72) connected with the receiving interdigital transducer (4); the sending interdigital transducer (3) and the receiving interdigital transducer (4) are rectangular interdigital electrodes formed by two comb electrodes which are interdigitated; corners of common terminals of the comb electrodes of the sending interdigital transducer (3) and the receiving interdigital transducer (4) are round corners. In order to effectively avoid a point effect, corner rounding treatment is adopted at joints of the ground wires and the interdigital electrodes, and the point field intensity is effectively reduced, thereby avoiding punch-through and improving reliability of a device.

A GPS baseband architecture provides flexibility and power consumption and chip area usage advantages. The GPS baseband architecture includes a first stage having a preamplifier coupled to a low noise amplifier, which is coupled to a mixer. A PLL provides the mixer with a frequency to convert a signal to a higher intermediate (IF) frequency. The output of the mixer is fed to a poly-phase filter. The output of the poly-phase filter is fed to a programmable gain amplifier (PGA), whose output is fed to an analog-to-digital converter (ADC) to produce an output GPS signal. A saturation bit of the ADC is used to control the PGA through a digital amplifier gain control (AGC) circuit.

The present invention discloses a complementary metal-oxide semiconductor fully-integrated 71-76GHz LC voltage controlled oscillator which is realized by using a differential NMOS cross-coupled structure, compared with a NMOS cross-coupled structure, contributed parasitic capacitance is smaller, and thus a higher oscillation frequency can be obtained. In addition, a U-shaped transmission line differential inductor is used by the differential inductor in the voltage controlled oscillator, an inductance value is small, and the oscillation frequency can be further improved. According to the oscillation circuit of the present invention, the tuning range is 70.97 GHz to 76.76GHz, the center frequency is smaller than 73.86GHz, phase noises are -89.47dBc/Hz and -116.2dBc/Hz at 1MHz and 10MHz frequency offsets, and the power consumption is 10.8 mW. The oscillation circuit can be the local oscillator signal source of an E-band wireless communication system and also can be the voltage controlled oscillator in a frequency synthesizer.

The invention aims to provide a TRM (time reversal mirror) technology based underwater positioning method, which mainly comprises the following steps: determining the coordinate position of each array element of a short baseline relative to a geodetic coordinate system, emitting a broadband linear FM (frequency modulation) interrogating signal to the position of an underwater transponder, and determining a signal emission time; receiving the broadband linear FM (frequency modulation) interrogating signal s (t) by the underwater transponder, and estimating a multi-path spread delay length t byusing the s (t); selecting a time window according to the t, and carrying out time reversal processing on the received signals within the range of the time window; carrying out relative real-time detection on the signal (subjected to time reversal) received by an overwater short baseline processor through sliding, and according to the obtained detection result, judging whether a correlation peak is over a preset threshold scope, if so, judging that an answer signal is arrived, and at this moment, determining a signal receiving moment; and calculating the delay inequality of four circuits of signals of a short baseline array so as to obtain a distance, then obtaining a target position through converged calculation. By using the method provided by the invention, the high precision and low noise requirements of a system can be satisfied, and the multi-path influence of an underwater channel cam be offset effectively.

The invention discloses a broadband tunable double-chirp radar pulse generator based on a microwave photon technology. The radar pulse generator can be applied to the field of pulse compression radars. According to the radar pulse generator, femtosecond laser pulses output by a mode-locked laser are divided into three routes, the three routes of pulses go through different chromatic dispersion devices and time delay devices respectively, are combined together through an optical combiner and mutually interfere in the high-speed photoelectric detector detection process, and finally broadband tunable double-chirp radar pulses are generated. The chirp pulses are generated through a microwave photon method, therefore, the output pulses have the large broadband, and then improvement of the distance resolution of a pulse compression radar is promoted; the generated pulse center frequency can be determined through the delay capacity of an electronically-controlled optical fiber delay line, and the tunable advantage is achieved; meanwhile, the device has the excellent advantages of being low in loss and resistant to electromagnetic interference.

The invention relates to a line-focusing ultrasonic probe used for Lamb wave velocity measurement on anisotropic materials and belongs to the technical field of acoustic transducer. The role of the line-focusing ultrasonic probe is to convert pulse electric signals generated by an excitation source into vibration of piezoelectric thin films so as to generate ultrasonic signals, and meanwhile to receive reflection echoes of a tested sample and convert the ultrasonic signals into electric signals. By adopting a piezoelectric high molecular polymer as an exciting or receiving element, a joint, a metal spring, an upper metal shell, a lower metal shell, an insulating sleeve, a backing, insulation paste, an evaporation plating electrode and the like can generate ultrasonic signals with center frequency of 5MHz. No stretching operation is needed during the polarization process, and thus polarization difficulty is greatly reduced. The line-focusing ultrasonic probe provided by the invention has the advantages of long defocus distance, wide frequency band, high signal-to-noise ratio and the like, and can fully meet the need of experimental analysis.

The invention discloses a miniature dual-stop band microstrip filter. A DGS is etched on an earth plate; an SRR is added into the gap of the DGS; and a dielectric slab with a dielectric constant epsilon of 2.6 is filled between a central transmission line and the earth plate. The invention is a planar microstrip dual-stop band filter, which has two stop bands of 3.62 GHz to 5.19 GHz and 6.13 GHz to 8.37 GHz. As the planar technology is adopted to arrange the SRR in the gap of the DGS, the size of the structure is very small compared with the traditional dual-stop band filter. The SRR is arranged in the gap of the DGS and two stop bands are generated as both of the SRR and the DGS have resonant effects. Moreover, due to the coupling effect of the SRR and the DGS, when the width of the gap of the DGS is increased, the central frequency of the two stop bands is reduced.

A voltage controlled oscillator (VCO) for use in a personal area network synthesizer includes a delay cell (100), a first current amplifier (201, 203) for amplifying an input current, a resister capacitor (RC) tuning network (207, 209, 211) for varying the amount of amplification and delay of an output of the first current amplifier. A second current amplifier (213, 215) is then used for amplifying an output current from the RC tuning network. The invention includes a unique composite voltage variable capacitor (CVVC) (300) for precisely tuning the amount of delay presented by the delay cell. The unique topology of the delay cell (100) allows it to be readily used in voltage controlled oscillators (VCOs) operable at frequencies above 1 GHz.

The present invention provides a microresonator including a plurality of resonator elements arranged on a plurality of columns on a substrate. The resonator elements each have an input electrode, an output electrode, and a diaphragm that extends in a certain direction, and each pass a signal of a certain frequency. The plurality of resonator elements includes a plurality of first resonator elements arranged on first columns that are located on every other column of the plurality of columns, and having a first phase, and a plurality of second resonator elements arranged on second columns that are located on every other column, other than the first columns, of the plurality of columns, and having a second phase that is an opposite phase of the first phase.

A device and method for generating an adjustable chaotic signal are provided. The chaotic signal generation device includes a plurality of triangle pulse train generators which generate a plurality of triangle waves having different frequency cycles, an adder which adds the triangle waves output from the triangle pulse train generators and outputs a noise signal, and a frequency modulator which converts the noise signal to a certain frequency band to output a chaotic signal. Accordingly, the power consumption and cost are reduced and the manufacture of the chaotic signal generation device is simplified due to the components integrated on an IC. Also, a plurality of users can use wireless communications in a particular wireless communications area.

The invention discloses a broadband Doherty power amplifier based on a load modulation network. The broadband Doherty power amplifier comprises a broadband power divider, a carrier power amplification module, a peak power amplification module and the load modulation network. The carrier power amplification module comprises a carrier input matching/biasing network, a carrier power amplifier, a carrier output matching/biasing network and a carrier power amplifier impedance conversion line; the peak power amplification module comprises a peak power amplifier phase compensation line, a peak input matching/biasing network, a peak power amplifier and a peak output matching/biasing network; and the load modulation network comprises a dual-band impedance transformer composed of a pi-shaped impedance transformer and an L-shaped branch line. According to the Doherty power amplifier, the load modulation network is used for ensuring the drain efficiency and the rollback efficiency of the Doherty power amplifier and expanding the bandwidth at the same time, and meanwhile, the Doherty power amplifier is compact in structure and beneficial to miniaturization design.