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:
Apr. 14, 1998
Filed:
Nov. 13, 1995
Jaakko Hulkko, Oulu, FI;
Merja Vuolteenaho, Helsinki, FI;
Nokia Mobile Phones Ltd., Salo, FI;
Abstract
In the frequency synthesizer, the stable transmission frequency required by the digital operating mode is created from a frequency produced by a free running oscillator and which includes frequency errors. A local frequency (f.sub.1) and an intermediate frequency (f.sub.IF) including frequency errors are input to a mixer (105) located in the signal path of the transmitter. A transmission frequency transmission signal (f.sub.TX) is input to a phase-lock loop with a voltage-controlled oscillator (103) that produces the local frequency (f.sub.1). Thereby the frequency error caused by the intermediate frequency (f.sub.IF) can be corrected with the local frequency (f.sub.1) by adjusting the voltage-controlled oscillator (103) of the loop with a voltage (V.sub.D) that is proportional to the phase difference between the transmission frequency signal and a reference signal (V.sub.REF) input to a phase comparator. This is implemented by connecting the mixer (105) to the loop during the transmission time period with a controllable switch (104), for example. The local frequency (f.sub.1) of the receiver is produced with the frequency synthesizer described in the present invention by disconnecting the mixer (105) from the loop. The invention can be applied in producing frequencies for radio telephones that include dual-mode operating modes and exclusively digital operating modes.