40 results about "Elliptic filter" patented technology

The present invention relates generally to digital elliptic filters, and more particularly, but not exclusively to multi-layer digital elliptic filters and methods for their fabrication.

An analytical Synthesis Method (ASM) is clearly and effectively demonstrated in the realization of current / voltage-mode Operational Trans-conductance Amplifier and Capacitor (OTA-C) circuits, where a complicated nth-order transfer function is manipulated and decomposed by a succession of innovative algebra operations until a set of simple equations are produced, which are then realized using n integrators and a constraint circuitry. The circuits realized includes voltage-mode nth-order OTA-C universal filter structures, tunable voltage / current-mode OTA-C universal biquad filters, voltage-mode odd / even-nth-order OTA-C elliptic filter structures, voltage / current-mode odd-nth-order OTA-C elliptic high-pass filter structures, and OTA-C quadrature oscillators. Some realized OTA-C circuits can be simplified to be OTA-only (OTA-parasiic C) circuits which fit for the operation at high frequencies.

The invention provides a parallel connection type unilateral elliptic function transmission line filter composed of transmission line elements. Input signals are fed into a first parallel connection cross joint (2) from an input transmission line (1) and divided into two paths to be transmitted to a second parallel connection cross joint (7) respectively through a cascading transmission line joint (3) and a parallel connection transmission line joint (4), and two paths of the input signals are synthesized and then output from an output transmission line (8). Two open circuit transmission line branch joints are connected to the two parallel connection cross joints respectively to adjust the amplitude of reflected signals. As for given cut-off frequency fc, various transmission line element parameters are selected, more than two nonzero limited frequency reflection null points with frequency lower than or higher than fc are generated, and a passing band is generated nearby a frequency band of the nonzero limited frequency reflection null points; meanwhile, more than two nonzero limited frequency transmission null points with frequency higher than or lower than fc are generated, a stop band is generated nearby a frequency band of the nonzero limited frequency transmission null points, and therefore filter characteristics of a unilateral elliptic function nearby fc are achieved. The filter is suitable for bandwidth below the medium degree of microwave and millimeter wave frequency bands, low loss, high selectivity.

The invention discloses a 2.45GHz closed loop microwave power transmission system based on phase control. The 2.45GHz microwave power transmission system comprises a microwave transmitting microstripantenna, a microwave receiving microstrip antenna, a digital phase shifter, a rectifier diode, a low-pass input elliptic filter, an output filter, a matching circuit, a sampling circuit, a controllerand a WIFI module, wherein a flexible board uses hair felt cloth; and the transmitting microstrip antenna and the receiving microstrip antenna of the 2.45GHz microwave power transmission system adoptlinear polarization rectangular microstrip antennas with the center frequency of 2.45 GHz, and feeding is realized in a microstrip line side feed manner. According to the system, the microwave phase is changed by controlling the digital phase shifter in an MPPT manner, and the directionality of microwave transmission is improved, so that more energy can be received by a microwave receiving antenna, and the transmission efficiency of the microwave power transmission system is improved. The efficiency of the microwave power transmission system can reach 70% at most.

The invention discloses the design of a DDS signal generator applied to a WPT system. The DDS signal generator applied to the WPT system mainly comprises a DSP control circuit, a DDS signal generator circuit and a seven-stage elliptic filter circuit. The DDS signal generator belongs to the frontier field of the high-frequency electromagnetic theory and the control engineering application of the high-frequency electromagnetic theory, provides a high-performance excitation source for the WPT system and can guarantee that electric energy can be transmitted continuously and stably. The DDS signal generator applied to the WPT system is wide in frequency band, high in intelligentization and high in reliability and is designed to be suitable for electric energy transmission for the first time according to the wireless electric energy transmission characteristic.

Disclosed is a complex elliptic filter having an order of three or higher which receives two differential signals that differ in phase from each other by 90 degrees are applied and outputs two differential signals that differ in phase from each other by 90 degrees. The complex filter circuit has internally at least two circuit blocks that include a capacitor connected in series with a coupler (gyrator). The complex filter is a third-order inverse Chebychev filter having an equiripple stopband of 40-dB attenuation amount. Alternatively, the coupler (gyrator) between elliptic capacitors is removed. Alternatively, the elliptic capacitors are made substantially equal to the capacitor arranged in parallel therewith. Alternatively, the gm value of an OTA and the capacitance value are each in an integral ratio represented substantially by a geometric progression of 2.

The invention relates to a structure of an interleaver based on a cascaded optical fiber circulator and a design method thereof, and belongs to an interleaver technology, which is used for solving the problems of the existing optical multiplexer such as poor spectral transmittance, uneven output spectrum and low isolation. In the method, frequency domains in the formulas of two output port spectrums are converted into z domains by adopting a digital signal processing mode, and then pole-zero characteristics in the z domains are analyzed; the output spectrums with equal bandwidth can be obtained only if all poles in the formulas of the output spectrums are positioned on an imaginary axis; length of various cascaded annular cavities and length difference of MZ (Mach-Zehnder) interference arms can be obtained in combination with orders of an elliptic filter; and the coupling angles of couplers for various fiber annular cavities are solved by virtue of the pole values of the elliptic filter. The interleaver with equal bandwidth designed by the method has two output spectrums which have the characteristics of high flatness, high bandwidth utilization ratio, high isolation and the like; and especially under the condition of the cascaded optical annular cavities with more stages, the interleaver has the advantages of simple computation and high accuracy.

The invention discloses an elliptical surface acoustic wave filter. The elliptic surface acoustic wave filter comprises at least four resonance units, a first resonance unit and a second resonance unit are connected in series, and a third resonance unit and a fourth resonance unit are connected in parallel between a reference potential point and a series point of the first resonance unit and the second resonance unit; the resonant frequencies of the third resonant unit and the fourth resonant unit are different; the circuit structures of the four (first to fourth) resonance units are the same;a circuit structure formed by all the resonance units satisfies a transfer function Gn(omega) of the elliptic filter. According to the elliptic surface acoustic wave filter, any relative filter bandwidth can be realized on a piezoelectric substrate with a high electromechanical coupling coefficient.

The invention discloses a semi-lumped microwave band-pass filtering circuit and a filter. The semi-lumped microwave band-pass filtering circuit and the filter are based on a design theory of a conventional elliptic function filter, and input and output ports are subjected to high-and-low pass matching, so that the problem of gentle out band rejection of the elliptic function filter is solved. The semi-lumped microwave band-pass filtering circuit and the filter are mainly used for rejecting clutter interference, meanwhile, have better phase congruency compared with band-pass filtering devices with other structures, and can be widely applied to antennas used in communication systems.

The invention provides a design method of a fractional order elliptic filter with a linear phase. According to the method, a Bessel filter is cascaded behind a fractional order elliptic filter. The method specifically comprises the steps of: performing initialization, randomly generating an initial zero point and a pole of the fractional order elliptic filter; calculating a zero pole of the elliptic filter; performing algorithm iteration on a zero pole; outputting the optimal solution of the fractional order elliptic filter, respectively calculating the group delay of the elliptic filter and the group delay of the Bessel filter, carrying out the algorithm iteration, and finally outputting the order n of the Bessel filter and the optimal solution of the fractional order elliptic filter, thereby completing the design of the fractional order elliptic filter with the linear phase. According to the method, the nonlinear phase of the fractional order elliptic filter is compensated by utilizing the good phase characteristic of the Bessel filter, and the poor transition zone characteristic of the Bessel filter is compensated by virtue of the steep transition zone characteristic of the elliptic filter, so that the filter performance with excellent performance is obtained, and the method has good engineering practicability.

The invention relates to the field of signal generator, and specifically relates to an arbitrary waveform generator based on a PXIe bus. The generator comprises a waveform generation part and a waveform conditioning part. The waveform generation part comprises an FPGA and a crystal oscillator. The waveform conditioning part comprises a 16-bit DAC, an operational amplifier, an SPI program control amplifier, a filter circuit, an SPI program control DAC, a differential operational amplifier, and a subtracter. The generator employs the PXIe bus as a channel which is used by an upper computer for transmitting waveform data. The FPGA continuously process the waveform data transmitted by the upper computer in a waveform generation process, so as to guarantee the integrity of high-frequency signal quality. In a waveform conditioning process, the generator respectively employs a Bessel filter and an elliptic filter according to the frequency characteristics of signals and the difference of anti-noise capabilities, and meets the filtering requirements of different types of signals. For a signal with the amplitude being less than 50mV, a small signal processing branch circuit is designed, thereby guaranteeing that a signal with a small amplitude value cannot be flooded by noise. The generator employs a mode of internal and external synchronization adjustment for signal amplitude and bias, and guarantees the accuracy of a signal.

The invention relates to a method for designing an arbitrary duty ratio Michelson Gires-Touruois interferometer type unequal bandwidth optical interleaver. The method simplifies complicated transmissiThe invention relates to a method for designing an arbitrary duty ratio Michelson Gires-Touruois interferometer type unequal bandwidth optical interleaver. The method simplifies complicated transmissig a plurality of reflectors, and has wide application prospect in special wave filter, gain equalization and other fields.vantages for the situation of cascading a plurality of reflectors, and has wide application prospect in special wave filter, gain equalization and other fields.advantages for the situation of cascadinh utilization, high isolation, and the like for two paths of output spectrums. Particularly, the design method does not require programming for calculation, has simple calculation, represents betteradth utilization, high isolation, and the like for two paths of output spectrums. Particularly, the design method does not require programming for calculation, has simple calculation, represents betterteaver into sum and difference of two all-pass filters with adjacent exponent numbers. The unequal bandwidth optical interleaver designed by the method has the characters of high flatness, high bandwideaver into sum and difference of two all-pass filters with adjacent exponent numbers. The unequal bandwidth optical interleaver designed by the method has the characters of high flatness, high bandwidon of a multi-mirror GT cavity and the expression of a light wave electric vector in a reflection direction through z transform in a digital signal processing, calculates the expressions of transmission of a multi-mirror GT cavity and the expression of a light wave electric vector in a reflection direction through z transform in a digital signal processing, calculates the expressions of transmission functions of two paths of output ports of the optical interleaver on the basis, and obtains the cavity length and the arm length difference of the GT cavity, and the reflectivity of each mirror suron functions of two paths of output ports of the optical interleaver on the basis, and obtains the cavity length and the arm length difference of the GT cavity, and the reflectivity of each mirror surface of the GT cavity with design principle of an elliptic filter by a limit point value of a transfer function. Particularly, an even-order Michelson Gires-Tournois interferometer type optical interlface of the GT cavity with design principle of an elliptic filter by a limit point value of a transfer function. Particularly, an even-order Michelson Gires-Tournois interferometer type optical interleaver with definite exponent number can be designed to realize the arbitrary duty ratio optical interleaver throughby respectively decomposing two paths of transmission functions of the optical interleaver with definite exponent number can be designed to realize the arbitrary duty ratio optical interleaver throughby respectively decomposing two paths of transmission functions of the optical interl

The invention discloses a method for improving alignment signal processing accuracy based on adaptive correction processing. The method uses an elliptical side lobe filter to achieve better filtering effect; and uses a method for checking whether the alignment position is within the capture range , adaptively update the scan center and scan range, improve the adaptability of the alignment scan to the size of the spatial image, thereby improving the repeatability and scanning efficiency of the alignment scan; provide adaptive update threshold constant value and threshold filtering The processing method improves the adaptability of the alignment scan and the accuracy of the alignment scan.

The present invention relates to a high frequency electromagnetic wave transmitter which comprises a frequency demultiplier, a gating switch, a filter, a transmission drive unit, a power amplification unit and an output end resonance loop which are in electric connection orderly. The output end resonance loop is connected with a transmission coil by a coupling transformer and forms an integral resonance loop together with the coupling transformer and the transmission coil. The transmitter uses the coupling transformer, temperature compensation, seven-step elliptic filter and a transistor C-class amplification circuit; compared with the prior art, the transmitter has the advantages of high transmission efficiency, good temperature characteristic, etc. The circuit design of the transmitter can be fit for various kinds of high frequency electromagnetic wave well logging tools with one or multiple transmission frequencies less than 15MHz and can work normally within a large temperature range between 25 DEG C and 150 DEG C.

The present invention discloses a universal PSK (phase shift keying) modulation and demodulation system. The system comprises a universal demodulator module, an FPGA (Field-Programmable Gate Array) chip, a modulation signal generator module, a PCI (Peripheral Component Interconnect) data bus module and a power module. The universal demodulator module comprises an interface circuit and an analog-digital converter, the interface circuit comprises an S-K filtering circuit, a voltage conversion circuit and a single-end-to-difference circuit; the FPGA chip is internally provided with a demodulationalgorithm module, a modulation algorithm module, a PCI control module and an SPI (Serial Peripheral Interface) controller; the modulation signal generator module comprises a digital upper converter,a signal output circuit and a seven-order elliptic filter; the PCI data bus module comprises a golden finger circuit board, an SDRAM (Synchronous Dynamic Random Access Memory) chip, a PCI interface chip and an EEPROM (Electrically Erasable Programmable Read-Only Memory); and the power module is connected with the golden finger circuit board. The universal PSK modulation and demodulation system canachieve rapid design and automatic code generation of the demodulation system so as to enhance the universality of the modulation and demodulation system.