Variable capacitance circuit

In order to form a variable capacitance circuit 36 with a desired linear characteristic from variable capacitance devices with highly non-linear characteristics, the circuit 36 comprises a plurality of variable capacitance devices 38n coupled to a common control voltage source 30, each variable capa...

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Bibliographic Details
Main Authors MARTIN ANDREW FRYER, ANDY COULTHARD, DAVID MARK CHAPMAN
Format Patent
LanguageEnglish
Published 09.01.2002
Edition7
Subjects
BASIC ELECTRIC ELEMENTS
BASIC ELECTRONIC CIRCUITRY
ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
ELECTRICITY
SELECTING RESONANT CIRCUITS
SEMICONDUCTOR DEVICES
TUNING RESONANT CIRCUITS
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Summary:In order to form a variable capacitance circuit 36 with a desired linear characteristic from variable capacitance devices with highly non-linear characteristics, the circuit 36 comprises a plurality of variable capacitance devices 38n coupled to a common control voltage source 30, each variable capacitance device being connected to a respective voltage offset means such as a drive amplifiers 40n, diodes (figure 8) or a resistance network (figure 7). In this way, for the range of control voltages, the variable capacitance devices are operative in different regions of their voltage capacitance characteristics each to contribute an incremental capacitance as the control voltage rises, whereby to provide an overall desired voltage capacitance characteristic. The invention makes the use of such variable capacitance devices practicable in circuits such as integrated circuit voltage controlled oscillators for application in wireless systems.
Bibliography:Application Number: GB20000015105