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1. (WO2010115723) TANK TUNING FOR BAND PASS FILTER USED IN RADIO COMMUNICATIONS

Pub. No.:    WO/2010/115723    International Application No.:    PCT/EP2010/053910
Publication Date: Fri Oct 15 01:59:59 CEST 2010 International Filing Date: Fri Mar 26 00:59:59 CET 2010
IPC: H03J 1/00
H03J 3/20
Applicants: TELEFONAKTIEBOLAGET L M ERICSSON (PUBL)
MU, Fenghao
Inventors: MU, Fenghao
Title: TANK TUNING FOR BAND PASS FILTER USED IN RADIO COMMUNICATIONS
Abstract:
A tuning method and circuit for an LC tank resonant circuit, including an inductor and a variable capacitor, are described. In a tuning mode, an RF input signal is applied to an input port of the circuit, and the RF output signal is monitored as a variable capacitor control input is varied. A peak output is detected, and the corresponding variable capacitor control input is stored, and applied to the variable capacitor in an operating mode. In one embodiment, the variable capacitor control input is adjusted for delay in the peak detection process. In one embodiment, the variable capacitor comprises a coarse capacitor and a fine capacitor; the tuning procedure is repeated for each capacitor; and both coarse and fine variable capacitor control inputs are stored and applied to the respective capacitors in operating mode.