A Tunable Bandpass-Bandstop Filter Based on Open-circuit Stub Loading

Abstract

The invention discloses an adjustable bandpass-bandstop filter based on loading on an open circuit branch. The adjustable bandpass-bandstop filter is manufactured on a two-sided copper clad micro-strip board in a printed circuit board way; a feeder port port1 and a feeder port port2 used for inputting or outputting electromagnetic wave signals, a first micro-strip line, a second micro-strip line, a first multimode loading resonator and a second multimode loading resonator are respectively manufactured on the same side of the two-sided copper clad micro-strip board; and a copper clad ground board is arranged on the other side of the two-sided copper clad micro-strip board. According to the filter, a varactor is loaded at the tail end of the open circuit branch, so that the capacitance of the varactor is adjusted through controlling the voltage of the varactor, and then the center frequency of the filter is adjusted; however, the adjustment of the bandpass-bandstop characteristic is controlled by a PIN diode. The filter disclosed by the invention has the advantages of being capable of switching between the bandpass filter and the bandstop filter, controllable in center frequency, simple in structure and small in size.

Description

technical field [0001] The invention relates to the technical field of planar microstrip filters, in particular to an adjustable bandpass-bandstop filter based on open circuit stub loading. Background technique [0002] In recent years, the rapid development of wireless communication, the popularity of 3G technology, and the arrival of 4G all indicate that wireless technology will usher in a peak period of vigorous development. At the same time, with the popularity of wireless electronic products in people's lives, miniaturization and low cost have become the trend of electronic products. On the other hand, with the rapid development of electronic information, the increasingly scarce spectrum resources are becoming more and more scarce. In order to improve the communication capacity and reduce the signal crosstalk between adjacent channels, higher requirements are put forward for the selectivity and integration of filters. The microstrip filter meets these requirements. ...

AI Technical Summary

Problems solved by technology

The switch used in this filter is an RF MEMS switch. Although this switch has excellent characteristics, its expensive cost limits its popularization and application. However, this patent uses a PIN diode to control the selection of band-pass-band-stop characteristics, and the PIN diode Wide application, mature technology, cheap and easy to get

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