Electronic filtering circuit for mobile telephone, has active circuit parallely branched on acoustic resonator and generating value of negative capacitance acting on parallel resonance frequency of acoustic resonator

摘要

#CMT# #/CMT# The circuit has an acoustic resonator e.g. bulk acoustic wave resonator (31) or surface acoustic wave resonator, including a series resonance frequency and a parallel resonance frequency. An active circuit is parallely branched on the acoustic resonator and generates a value of negative capacitance (32) acting on the parallel frequency of the resonator. An adjustable capacitance element e.g. varactor, provided in series with the resonator and the active circuit adjusts the series frequency. #CMT#USE : #/CMT# Electronic filtering circuit for forming a radio frequency signal receiving circuit in a mobile telephone (claimed). #CMT#ADVANTAGE : #/CMT# The integration of the resonator to the filtering circuit enables easy integration over a semiconductor substrate and provides wide variety of functionalities. The configuration of the filtering circuit eliminates the need for inductance for ensuring tuning of the resonator, permits filtering operation in an efficient manner without degrading quality factor and without creating parasitic anti-resonance frequency. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a simplified circuit diagram of a resonance circuit. 31 : Bulk acoustic wave resonator 32 : Negative capacitance.