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Wideband acoustic surface-wave switching filter set

A technology of switching filter banks and surface acoustic waves, which is applied to impedance networks, electrical components, and networks using time-varying components. Effect

Inactive Publication Date: 2009-09-23
INST OF ACOUSTICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But if each channel of the filter bank uses a longitudinally coupled filter with the same structure made on the same substrate, when the center frequency of the last channel is approximately twice the center frequency of the first channel, then the last channel The bandwidth of the channel is also approximately twice the bandwidth of the first channel (such as Figure 8 shown), so it is not possible to achieve the same bandwidth as possible for each channel

Method used

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  • Wideband acoustic surface-wave switching filter set
  • Wideband acoustic surface-wave switching filter set
  • Wideband acoustic surface-wave switching filter set

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] figure 1 It is the principle block diagram of the broadband surface acoustic wave switchable filter group of the present invention, which is composed of a plurality of surface acoustic wave filters 2 and one-knife multi-throw switch 1, and an external driving signal can control two groups of switch arrays to switch simultaneously, so that in a certain Only one of the channels is turned on at any time, and the other channels are turned off, and all the power of the input signal is added to this channel to ensure that there is no loss of the combined network. A single SAW filter chip adopts a longitudinally coupled resonant structure. Due to the wide span of the passband of the filter bank, in order to achieve the same bandwidth of each channel as possible, a 1-2 mode longitudinally coupled resonant structure (such as Figure 2A ) or 1-3 mode longitudinally coupled resonant structures (such as Figure 3A ). The details are as follows, when the relative bandwidth of a c...

Embodiment 2

[0046] On the basis of embodiment 1, when the channel increases to 16 channels (the center frequency of the last channel in the 16 channel filter banks of this embodiment is about 2 times of the center frequency of the first channel), 1-12 channels Adopt the same scheme as embodiment 1, channel 13-channel 16, adopt 64 ° Y-X LiNbO on the substrate 3 The 1-3 mode longitudinal coupling structure is fabricated on the above.

Embodiment 3

[0048] On the basis of embodiment 2, when the channel increases to 20 channels, 1-16 channels adopt the same scheme as embodiment 2, and channel 17-channel 20 adopts 64 ° Y-X LiNbO on the substrate 3 The 1-2 mode longitudinal coupling structure is made above, and it can be adjusted according to the actual situation in the specific operation.

[0049] When the number of required channels increases, by analogy with the above rules, each channel can have approximately the same bandwidth filter components.

[0050] Figure 2A The surface acoustic wave filter chip shown is composed of a piezoelectric substrate 3, two interdigital transducers 4, 5 fabricated on the piezoelectric substrate 3, and metal reflection grid arrays 6, 7 at both ends thereof. The interdigital transducers 4 and 5 are not weighted, and the width and spacing of the interdigital electrodes are 0.25 wavelengths. The metal reflective grid arrays 6 and 7 use short-circuit grids, and the width and spacing of the gr...

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Abstract

The invention relates to a wide-band low-loss switchable surface acoustic wave filter group. The filter bank is composed of two sets of one-knife multi-throw switches and multiple surface acoustic wave filters made on the printed circuit board. One set of switches connects the input ends of multiple surface acoustic wave filters together, and the other A group of switches connects the output ends of a plurality of SAW filters together, and the two sets of switches correspond to each other; the SAW filters all adopt a longitudinally coupled resonant structure to achieve low insertion loss; in different On the channel, several different longitudinal coupling structures are used to obtain the same bandwidth as possible on each channel; the substrate material is lithium niobate, lithium tantalate and other piezoelectric materials. The present invention provides a wideband (single-channel relative bandwidth 2%-7.3%), low insertion loss (less than 6.5dB including the switch) and high stop-band suppression (greater than 40dB) switchable switch applied in the communication system SAW filter bank.

Description

technical field [0001] The invention relates to a surface acoustic wave switchable filter group used in communication, in particular to a wideband low-loss surface acoustic wave switchable filter group. Background technique [0002] The surface acoustic wave filter bank is composed of multiple surface acoustic wave filters plus matching networks and switching circuits, and has one input and multiple output components. The output signal is divided by frequency, which can be used for frequency sorting and synthesis. It is mainly used in frequency synthesis, frequency hopping communication and other systems. The present invention relates to a surface acoustic wave filter bank applied to a frequency hopping communication system. [0003] A big disadvantage of the prior art is that the filter insertion loss is large, thus limiting the bandwidth and the number of channels of the filter bank. This is a result of the traditional bi-directional transducer design used in the prior ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H19/00H03H11/00H03H9/64
Inventor 何世堂刘久玲李顺洲
Owner INST OF ACOUSTICS CHINESE ACAD OF SCI