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1. (WO2014207300) METHODS AND APPARATUS FOR SIGNAL FILTERING

Pub. No.:    WO/2014/207300    International Application No.:    PCT/FI2014/050482
Publication Date: Thu Jan 01 00:59:59 CET 2015 International Filing Date: Thu Jun 19 01:59:59 CEST 2014
IPC: H03H 7/12
H03H 7/01
H03H 11/12
H03H 9/52
H03H 9/64
H01P 1/208
H03H 9/50
H03H 9/56
H03H 9/60
Applicants: NOKIA TECHNOLOGIES OY
Inventors: REIHA, Michael
Title: METHODS AND APPARATUS FOR SIGNAL FILTERING
Abstract:
A plurality of tunable cross-coupled resonators (1-5) are connected using capacitive coupling elements (212, 214, 216, 218) to form a cross-coupled bandpass filter (200). A center frequency of the filter (200) may be set based on frequencies of the resonators (1-5) and a fractional bandwidth of the filter may be set based on states of the capacitive coupling elements (212, 214, 216, 218). Programmable zeroes of the filter (200) may be set based on states of reactive elements (228, 230) coupling selected pairs of the resonators. The reactive elements may be capacitive, for zeroes below the center frequency, or inductive, for zeroes above the center frequency.