Microphony limiting method for portable telephone, involves using auxiliary synthesizer for doubling main synthesizer and comparing signals of synthesizers to form inverse feedback with output signal representing phase/frequency variations

摘要

#CMT# #/CMT# The method involves placing a reference oscillator in a module of a receiver system, and transmitting an external reference signal (Sref) from the module to another module. An auxiliary synthesizer (PLO2) is used for doubling a main synthesizer (PLO1) of latter module, where the main and auxiliary synthesizers respectively include an optimized loop filter (F1) and wideband filter (F2). Signals from the synthesizers are compared by a phase/frequency comparator (C) to form an inverse feedback with an output signal that represents phase/frequency variations caused due to microphony phenomenon. #CMT# : #/CMT# An independent claim is also included for a receiver system comprising modules. #CMT#USE : #/CMT# Method for limiting microphony in a receiver system (claimed) of a portable telephone. #CMT#ADVANTAGE : #/CMT# The method simplifies mechanical maintenance of the module sensible to microphony, and prevents blockage of redhibitory images during video transmission. The method is easy to implement, and effectively limits the microphony generated by voltage controlled oscillator of the receiver system. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a block diagram of architecture of a synthesizer module. C : Phase/frequency comparator F1 : Optimized loop filter F2 : Wide band filter PLO1 : Main synthesizer PLO2 : Auxiliary synthesizer Sc : Control signal Sref : External reference signal VCO1, VCO2 : Voltage controlled oscillators.