SAW ladder filter
First Claim
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1. A SAW filter comprising:
- a first SAW resonator element provided in a series branch of the SAW filter and a second SAW resonator element provided in a parallel branch of the SAW filter, wherein the first and second SAW resonator elements form a ladder filter network having an input signal terminal and an output signal terminal; and
at least two parallel connected third and fourth SAW resonator elements provided in the series branch of the SAW filter and connected to at least one of the input and the output terminals.
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Abstract
A SAW filter useful in cellular telephone communications includes SAW resonator elements provided in a series and parallel branches for forming a ladder filter network, and SAW resonator elements connected in parallel and provided in the series branch of the SAW filter for providing improved ESD protection to the SAW filter. The SAW filter is effectively used with an ESD protection circuit and a triplexer for receiving and separating low, high, and bandpass frequencies.
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Citations
18 Claims
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1. A SAW filter comprising:
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a first SAW resonator element provided in a series branch of the SAW filter and a second SAW resonator element provided in a parallel branch of the SAW filter, wherein the first and second SAW resonator elements form a ladder filter network having an input signal terminal and an output signal terminal; and
at least two parallel connected third and fourth SAW resonator elements provided in the series branch of the SAW filter and connected to at least one of the input and the output terminals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A SAW triplexer operable for receiving signals in at least three frequency bands, the SAW triplexer comprising:
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a low pass filter connected to an input terminal for receiving and separating an incoming signal into a preselected low frequency band;
a high pass filter connected to the input terminal for receiving and separating the incoming signal into a preselected high frequency band; and
a SAW bandpass filter having SAW resonator elements provided in series and parallel branches of the SAW bandpass filter, wherein the SAW resonator elements form a ladder filter network having an input signal terminal and an output signal terminal for the receiving and separating of the incoming signal at a frequency band located between the preselected low and the preselected high frequency bands, and wherein at least two parallel connected third and fourth SAW resonator elements provided in the series branch of the SAW filter and connected to at least one of the input and the output terminals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification