| 摘要 |
A surface acoustic wave filter device includes a plurality of surface acoustic wave convolvers each having an output electrode between two input transducers, one of the input transducers of each convolver receiving a reference signal through a respective matching circuit. The other input transducer of one of the convolvers receives an input signal through a matching circuit, and the other input transducer of the rest of the convolvers receives through a respective input matching circuit and low pass filter from a respective mixing circuit a mixture of the reference signal and a respective output signal received from the output of a respective output matching circuit having an input coupled to the output electrode of a respective convolver. The remaining convolver has an output electrode coupled to a further output matching circuit. In one embodiment, a low pass filter receives from a mixing circuit a mixture of the reference signal and the output from the further output matching circuit. In a variation, the output of the further output matching circuit is connected to a detecting circuit.
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