The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 06, 1997
Filed:
Jan. 26, 1995
Kimmo Ervasti, Varjakka, FI;
LK Products Oy, Kempele, FI;
Abstract
An advantageous embodiment of the invention is the filter of the receiver branch of the duplex filter in a multi-channel radio transmitter/receiver having reception and transmission bands composed of plural radio-frequency channels. In the first state of the filter, when the radio transmitter/receiver is only receiving radio signals, the width of the pass band of the filter corresponds to said reception band. In the second state, in which the radio transmitter/receiver additionally transmits radio signals, the pass band of the filter is switched by current control to cover only part of the reception band. By constructing the filter in the manner proposed it is possible to use current control in the first resonator in the filter of the receiver branch. Because of its power consumption current control is otherwise unsuitable for use in e.g. the duplex filter of a portable radio-telephone.