7results about How to "Improve frequency selectivity" patented technology

The invention provides a Q-value-variable bisecond-order filter based on resistance feedback, and belongs to the technical field of radio frequency receivers. Differential source followers are adopted to form a second-order filtering unit, a cross coupling resistance network is introduced between differential signal nodes, and a novel method for adjusting the quality factor of the filter is provided. The quality factor Q of the filter can be independently adjusted through an equivalent feedback path formed by the cross coupling resistor in a differential working state. In addition, a parasitic zero offset method is provided, negative capacitance is achieved by cross-coupling two capacitors between differential input and output nodes, and the stop-band suppression performance is improved. On the premise that the power consumption of the filter is not increased, the variable Q value and high linearity are realized, and the structure is suitable for a radio frequency receiver system and has a good engineering application prospect.

The utility model relates to cable detection technical field discloses a signal receiving circuit and receiver, line finder for line finder, this signal receiving circuit can include probe interface, radio chip, clock supply circuit, for any cable of detection, the cable one end access line finder's transmitter's cable interface, when the receiver probe of probe interface access detects the other end of the cable, radio chip can receive the line signal of line finder's transmitter transmission and generate audio signal, the audio signal of generation is given receiver's main control chip, and main control chip controls audio output device to output sound after receiving audio signal, to prompt line search result. Visible, the utility model can apply radio chip to the receiver of line finder, can simplify circuit structure on the basis of realizing signal reception, and the integration level is high, reduces its to the occupation of circuit board volume.

The utility model discloses a KU wave band band-pass waveguide filter comprising a lower seat which is internally provided with a ripple filtering groove penetrating through two sides; the upper cover is buckled at the top of the lower seat and is fixed, so that the corrugated filtering grooves are encircled to form a single filtering channel; the input end is arranged at one end of the filtering channel; the output end is arranged at the other end of the filtering channel, and the filtering channel can be communicated end to end under the action of the input end and the output end; the impedance transformer is arranged at the input end of the filtering channel; the impedance transformer comprises at least two right-angle bosses formed on one side wall of the lower seat. According to the KU wave band band-pass waveguide filter provided by the utility model, through the arrangement of the lower seat and the upper cover, a single filtering channel can be formed between the input end and the output end, and the inner side plane of the upper cover is attached to the top of the lower seat for assembly, so that the filtering channel can be formed, and meanwhile, the overall size can be reduced.

The application relates to the technical field of radio frequency wireless communication, in particular to a center frequency and bandwidth reconfigurable power amplifier, which comprises an input port, an input matching network, a stabilizing network, a transistor, a dynamic impedance matching network, a varactor diode DC bias, a reconfigurable band-pass filter network and an output port. The output matching network is designed, the varactor diode junction capacitance adjustable characteristic is utilized to realize the continuous adjustment of the center frequency and bandwidth of the reconfigurable band-pass filter network passband and the dynamic impedance matching between the reconfigurable band-pass filter network and the transistor drain, so that the continuous reconfiguration of the center frequency and bandwidth of the power amplifier is realized, the demand of the multi-frequency band operation of a communication system is met, the frequency adjustable flexibility is improved, the continuous adjustable frequency band range is increased, the frequency selectivity and the power amplifier efficiency are improved, the system complexity is reduced, and the reconfiguration cost is reduced.

The invention discloses a multiband microwave metasurface absorber, and relates to the technical field of microwave functional devices, the multiband microwave metasurface absorber comprises a plurality of unit structures which are periodically arranged, and each unit structure comprises a metal grounding layer, an intermediate dielectric layer and a top metal resonance structure which are arranged from bottom to top; the top metal resonant structure comprises a peripheral closed ring and a metal cross-shaped structure arranged in the center of the peripheral closed ring, and the peripheral closed ring is formed by connecting four square metal rings end to end; the size of each square metal ring and the size of the metal cross-shaped structure are configured to enable the absorber to excite at least two resonance absorption peaks with the quality factors larger than 400 in the microwave frequency band of 8 GHz to 20 GHz. The dual requirements of multi-band coverage and high-frequency selectivity are met at the same time.

This invention discloses a distributed LC resonant network Ku-band on-chip tunable low-pass filter. The filter includes an RF signal entering from port 1, flowing sequentially through five high-impedance microstrip lines. These five transmission lines are equivalent to five series inductors at high frequencies. At the nodes of adjacent microstrip lines, four high-impedance microstrip lines and four sets of capacitor switch arrays are connected in parallel. Each high-impedance microstrip line with a series capacitor switch array forms a parallel resonant circuit to ground. Two low-impedance open-circuit microstrip lines are connected in parallel at the input and output ports, respectively. The parasitic capacitance generated at high frequencies is used for impedance matching of the filter. The overall topology is equivalent to an eleventh-order Chebyshev low-pass filter. Compared to existing tunable on-chip low-pass filters, this invention's low-pass filter achieves adjustable cutoff frequency across the entire Ku-band, providing a wide tuning range while ensuring excellent overall performance such as high frequency selectivity, low loss, sufficient out-of-band rejection, and miniaturization.

The utility model relates to the technical field of optical fiber laser, specifically relates to a kind of based on phase continuous sweep frequency optical fiber laser, including shell, the inside one side of shell is fixedly installed with the multimode pump transmitter for emitting laser source, the output end of multimode pump transmitter is provided with phase modulator, the other end of phase modulator is provided with first fiber grating, the one side of first fiber grating away from phase modulator is connected with optical fiber body, the other end of optical fiber body is fixedly connected with second fiber grating, the other side of second fiber grating is fixedly connected with the multimode pump coupler of emission gain rear laser.Compared with prior art, the utility model, by being provided with first fiber grating and second fiber grating cooperate optical resonant cavity, and in optical resonant cavity outer wrapping heat pipe, the frequency of stable optical resonant cavity is ensured the stability of laser output frequency, and optical path length drift caused by heat effect can be reduced.