Micro mechanical adjustable microwave band-pass filter

Abstract

The invention discloses a band-pass filter with adjustable microwave of micromechanical. The microwave band-pass filter arranges a comb structure of the filter on a substrate of a microwave circuit. The comb structure of the filter comprises an input coupling unit, an output coupling unit and a resonator unit which is arranged between the input coupling unit and the output coupling unit and has aparallel arrangement with each other; the resonator unit comprises a planar alignment of medium impedance and a planar alignment of high impedance, wherein, one end of the planar alignment of medium impedance at the resonator unit is grounded and one end of the planar alignment of high impedance is an opened circuit; one or more micromechanical switches are in series or / and parallel connected in the planar alignment of high impedance; the micromechanical switches are connected with a control circuit of external electrical signals. By adopting the adjustable comb structure of the filter with resonant characteristics, the invention has the filtering characteristics and the adjustable characteristics; besides, the invention realizes the object of little parasitic effect, stable circuit in electricity, as well as simple technology and the invention can be widely used in technical fields such as wireless communication and radar circuit.

Description

technical field [0001] The invention relates to a filter device with adjustable filter characteristics such as passband frequency in the fields of radio frequency and microwave, in particular, a micromechanical adjustable microwave bandpass filter based on MEMS control device. Background technique [0002] Filters are a key RF component in wireless communications and radar circuits. Filtering out of image frequency interference, suppression of noise, frequency division multiplexing, and signal frequency selection in high-performance oscillation, amplification, frequency multiplication, and mixing circuits all require filters to achieve. In addition, effective broadband impedance matching network and coupling structure are also realized on the basis of filter structure. The miniaturization, broadband, mobility, and frequency agility enhancement of wireless communication equipment (including base stations and terminals), radar, and electronic warfare equipment, as well as the...

AI Technical Summary

Problems solved by technology

The first type of device can withstand high microwave power, and the microwave loss is low, but the ferrite control device is difficult to miniaturize, the corresponding bias circuit is complex, and the static bias current needs to be maintained, so the control power consumption is large, and the second type also It can withstand large microwave power, and the microwave loss is very small, but the adjustment requires a complex servo mechanism, and the control power consumption and device volume are large

Therefore, the application of the first and second types of filters is limited to microwave applications with low requirements for device miniaturization, stable power supply, and high power

The third type of filter can achieve monolithic integration and compact structure, but because the microwave needs to be transmitted through the PN junction and semiconductor material, the corresponding microwave loss and nonlinearity will significantly affect its passband performance, and the required bias The circuit is relatively complex and often needs to be composed of multiple transistors, and it is difficult to reduce the control power consumption, so it has not been promoted at present

Its disadvantages are: 1) Since the bridge molds are made of electroplated or sputtered pure metal, and the on-off is realized by the deformation of the bridge membrane, the bridge membrane is prone to fatigue, creep and other phenomena, which affects the Its reliability, 2) There is a large difference in thermal expansion performance between the metal and the high-resistance substrate, and the structural size and reliability are greatly affected when the temperature changes greatly; 3) The bridge mold structure design is mainly double-ended , the driving threshold is high (complex charge pump and other booster circuits are required), the size is close to that of traditional MIC (microwave integrated circuit) filters, the processing steps are many, there is the problem of easy adhesion in structure release, and it can withstand power Not high; 4) Users often need to make an electrical isolation structure between isolated high-frequency / DC control drive circuits on the same device to prevent leakage of radio frequency signals. Currently, these devices are made of wires composed of metal and silicon alloys for isolation Resistance, a photolithography plate needs to be made separately during processing, which increases the difficulty and cost of the process

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