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EP0818883A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Duplex filter

Assignee: Pulse Finland Oy
•
Filing: 1997-06-30
•
Granted: —
•
Expires: 2017-06-30
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Abstract

Abstract The invention relates to a radio-frequency filter with a good temperature stability and power handling capacity. The invention can be applied in the pre-stages of portable mobile telephone apparatuses, for example. The receiver branch (2) of the filter construction according to the invention employs two filter stages (3, 4), the first of which (3) attenuates the signal connected to the second filter stage, said second filter stage being a SAW filter (4). Said first filter stage (3) can be realized with a helix or dielectric resonator, for example. In a second embodiment of the invention, said first filter stage (3) is used to compensate for changes caused by the temperature dependence of the frequency response of the SAW filter (4). <IMAGE>

Inventors

  • 👤 Harri Närhi
  • 👤 Erkki Niiranen

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-07 15:53
CPC Classifications
H; H01; H01P; H01P1/00; H01P1/20; H01P1/213

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 146 words
A filter construction comprising: a receiver branch (2), which comprises at least two filter stages, and a transmitter branch (5), which comprises at least one filter stage, wherein first ends of said transmitter and receiver branches are connected to each other, characterized in that at least one receiver branch filter stage is a SAW filter (4), and the receiver branch further comprises at least one other filter stage (3), which is connected between the SAW filter and the receiver branch end connected to the transmitter branch in order to attenuate the transmitter branch signal power connected to the SAW filter, and the temperature dependence of the frequency response of said other filter stage (3) is arranged so as to substantially cancel the changes in the frequency response of the receiver branch (2) caused by the temperature dependence of the frequency response of the SAW filter (4).
Claim 2
Dependent Claim 19 words
The filter construction of claim 1, characterized in that said other filter stage (3) is a helix resonator (3).
Claim 3
Dependent Claim 19 words
The filter construction of claim 1, characterized in that said other filter stage (3) is a dielectric resonator (3).
Claim 4
Dependent Claim 35 words
The filter construction of claim 4, characterized in that said other filter stage (3) is a helix resonator (3) having a capacitive element (14, 15, 18) the capacitance value of which depends on the temperature.
Claim 5
Dependent Claim 31 words
The filter construction of claim 5, characterized in that said capacitive element (18) is formed by means of electrically conductive patterns (14, 15) on the support structure (13) of the helix.
Claim 6
Dependent Claim 38 words
The filter construction of claim 4, characterized in that said other filter stage (3) is a dielectric resonator (3) wherein the temperature dependence of the frequency response is determined through the choice of a suitable dielectric body material.

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