Frequency tuning apparatus and method for continuous-time filters

The present invention provides an apparatus and method of tuning the frequency characteristics of a continuous-time filter (40). First and second test signals (from 60) are provided to the filter and the respective first and second responses of the filter are measured (by 50). The first and second r...

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Bibliographic Details
Main Authors WOO, NAM SUNG, KHORRAMABADI, HAIDEH, TARSIA, MAURICE J
Format Patent
LanguageEnglish
French
German
Published 15.01.1997
Edition6
Subjects
BASIC ELECTRONIC CIRCUITRY
ELECTRICITY
IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS
MEASURING
MEASURING ELECTRIC VARIABLES
MEASURING MAGNETIC VARIABLES
PHYSICS
RESONATORS
TESTING
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Summary:The present invention provides an apparatus and method of tuning the frequency characteristics of a continuous-time filter (40). First and second test signals (from 60) are provided to the filter and the respective first and second responses of the filter are measured (by 50). The first and second responses are compared and, based on the comparison, a tuning control signal is provided (on 74) to the filter to tune its frequency response characteristics. Advantageously a single test signal can also be used to provide tuning in an off-line manner. During a tuning phase of operation, a first switch (70) connects a test signal generator (60) and disconnects a data signal generator (20) from the transmission input of the filter. A signal processor (50) receives a signal from the transmission output from the filter and produces the tuning control signal based on that signal. The test signal generator (60) comprises means (64) for providing a first test signal, which may be an alternating signal source ("A.C."), and means (62) for providing a second test signal, which may be a direct signal source ("D.C."). A second switch (66) is preferably provided for switching between the two sources. The signal processor (50) compares the signal from the transmission output of the filter during a direct signal phase with the signal from the transmission output of the filter during an alternating signal phase and produces the tuning control signal based on the comparison. The filter (40) comprises a variable capacitance circuit which at least partly determines the frequency response characteristics of the filter. The variable capacitance circuit is controlled by the tuning control signal from the signal processor.
Bibliography:Application Number: EP19960304913