Patent ID: 7583127

Claim:
A circuit to control the capacitance of a variable capacitor in a strictly linear mode through a steady tuning voltage and to achieve a high Q-factor at the same time; comprising: a set of individual small capacitors; a set of capacitor switching stages, each stage comprising; a switching device, allowing a steady ramp-up/ramp-down phase between the points of being fully switched on and fully switched off, and where said switching device is connected in series with one of said capacitors, to connect a multiple of said capacitors in parallel; a circuit to control the switching operation of said switching device in a steady ramp-up/ramp-down manner between the points of being fully switched on and fully switched off, comprising: a translinear amplifier to produce a ramp-up/ramp-down signal for said switching device, where said translinear amplifier is implemented within said circuit to control the switching operation; a common circuit to provide a set of input and output reference levels for each of said capacitor switching stages, used as input reference levels and output reference levels for each of said translinear amplifiers, comprised within said circuits to control the switching operation; and input signals, each dependent on the tuning voltage, dedicated for the voltage controlled capacitance change, provided to an input of all of said capacitor switching stages.