Radio frequency electrically adjusted band-pass filter with constant absolute bandwidth

A band-pass filter, radio frequency technology, applied in waveguide-type devices, circuits, resonators, etc., can solve the problems of large difference in insertion loss, inconvenient link gain distribution, high cost, etc., and achieve the second harmonic suppression. Effect

Inactive Publication Date: 2010-11-24
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existence of these parasitic passbands leads to poor frequency selectivity of the filter, which affects the overall performance of the RF front end
[0006] (3) The insertion loss of the electronically tuned bandpass filter is large and the insertion loss at different frequencie

Method used

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  • Radio frequency electrically adjusted band-pass filter with constant absolute bandwidth
  • Radio frequency electrically adjusted band-pass filter with constant absolute bandwidth
  • Radio frequency electrically adjusted band-pass filter with constant absolute bandwidth

Examples

Experimental program
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Effect test

Embodiment 1

[0060] Embodiment 1: 60MHz bandwidth with a constant absolute bandwidth radio frequency electronically adjustable bandpass filter

[0061] 60MHz bandwidth with a constant absolute bandwidth of the radio frequency electrically tuned bandpass filter structure such as figure 1 shown. The specific parameters are: the length of the first microstrip line 8 is 4.7mm, the length of the second microstrip line 9 is 13.3mm, the length of the third microstrip line 10 is 3.5mm, and the length of the fourth microstrip line 11 is 9.2mm. The fifth microstrip line 12 has a length of 20mm, the sixth microstrip line 13 has a length of 6.2mm, the width of the microstrip line is 1.2mm, the parallel capacitor 15 is 5pF, the series capacitor 16 is 8pF, the fifth microstrip line 12 and the seventh The distance between the microstrip lines 17 is 0.55mm. Figure 6 shows the results of simulation and actual measurement using the filter designed with the above parameters. The simulation and actual measu...

Embodiment 2

[0062] Embodiment 2: 80MHz bandwidth with constant absolute bandwidth radio frequency electronically adjustable bandpass filter

[0063] This filter structure is similar to the filter with 60Mhz bandwidth, but the specific parameters are different. The length is 2.8mm, the length of the fourth microstrip line 11 is 9.2mm, the length of the fifth microstrip line 12 is 22.0mm, the length of the sixth microstrip line 13 is 6.2mm, the width of the microstrip line is 1.2mm, and the parallel capacitor 15 is 3.3pF, the series capacitance 16 is 6.8pF, and the distance between the fifth microstrip line 12 and the seventh microstrip line 17 is 0.5mm. Figure 7 shows the simulation and actual measurement results of the filter designed using the above parameters, where the simulation and actual measurement are completed using Agilent's commercial electromagnetic simulation software ADS and E5071C network analyzer respectively. Figure 7(a) shows the transmission characteristics of the filt...

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Abstract

The invention discloses a radio frequency electrically adjusted band-pass filter with a constant absolute bandwidth. The band-pass filter consists of an upper-layer micro-band structure, a middle medium basal plate and lower-layer grounding meta, wherein the upper-layer micro-band structure comprises a first half wavelength resonator, a second half wavelength resonator, an input feed network, an output feed network, an input port and an output port, wherein a fifth micro-band line of the first half wavelength resonator and a seventh micro-band line of the second half wavelength resonator are arranged in parallel to form an interstage coupling structure; the first half wavelength resonator consists of a first micro-band line, a second micro-band line, a third micro-band line, a fourth micro-band line, a fifth micro-band line, a sixth micro-band line and a variable capacitance diode; and the second half wavelength resonator and the first half wavelength resonator have the same structure, and are symmetrically arranged based on the central axis of the interstage coupling structure. The radio frequency electrically adjusted band-pass filter has the characteristics of keeping the absolute constant bandwidth while resonating the center frequency and inhibiting second harmonic wave, and can be applied to the reconfigurable radio frequency front-end in wireless communication.

Description

technical field [0001] The invention relates to a radio frequency electronically adjustable bandpass filter with adjustable center frequency, in particular to a novel half-wavelength resonator and interstage coupling structure applicable to multi-band, wide-band and reconfigurable radio frequency front-end systems , when the center frequency is tuned, the absolute bandwidth remains constant and the electronically adjustable bandpass filter can well suppress the second harmonic. Background technique [0002] Modern ultra-wideband radar and wireless communications require high-performance reconfigurable RF front-ends. For example, in the cognitive radio system, in order to fully utilize and integrate various wireless channels and standards, the RF front-end needs to work at different frequencies, which requires a reconfigurable RF front-end with tunable center frequency. As an important part of the reconfigurable RF front-end, RF electronically tuned band-pass filters are rec...

Claims

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Application Information

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IPC IPC(8): H01P1/212H01P7/08
Inventor 章秀银胡斌杰魏晓东
Owner SOUTH CHINA UNIV OF TECH
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