Patent ID: 6819768
Filing Date: 2004-11-16
Classification: H03G

Abstract:
A volume control device comprising:a plurality of resistors, connected to one another in series, and a plurality of switches arranged to change connections between said resistors, to thereby change an overall gain of said plurality of resistors; a digitally adjustable resistor, selectively connectable across at least a plurality of different ones of said resistors, and variable between a high resistance which when connected across any of said ones of said resistors does not significantly change its resistance, and a low resistance which when connected across any of said ones of said resistors effectively eliminates its resistance; an operational amplifier, where the output of the operational amplifier is connected to a node which is between the resistor which is last in the plurality of resistors connected in series and an output of the volume control device; a plurality of setting switches, where each setting switch is connected to a corresponding node between two resistors of said plurality of resistors and connected to an input to the operational amplifier; and a plurality of transition switches, where each transition switch is connected to a corresponding node between two resistors of said plurality of resistors and connected to alternating ends of the digitally adjustable resistor.