Patent ID: 6937179
Filing Date: 2005-08-30
Classification: H03H

Abstract:
1. A resistor tuning network comprising: a first resistor having a fixed value of resistance R a resistor ladder network having a variable value of resistance R wherein said resistor ladder network comprises a first line comprising a plurality of first arms connected in series with the input of the resistor ladder network and the first output terminal of the resistor ladder network and nodes between each pair of arms, each arm having an identical resistor R, and a second line connected to said first output terminal of said resistor ladder network, and a third line connected to said second output terminal of said resistor ladder network; a series of shunt arms, each shunt arm having a first end connected to a respective node and a second end, a resistor which has a value which is a multiple of R and a switch in series between the first and second end of each shunt arm, each switch having a first, closed position connecting the shunt arm to the second line and a second, open position connecting the shunt arm to the third line, such that the resistance of the resistor ladder network is varied dependent on the switch positions and is at a maximum value when all switches are open and at a minimum value when all switches are closed, whereby a resistance can be tuned by varying the switch positions in the resistor ladder network; and a third resistor having a fixed value of resistance R wherein said resistor tuning network operates as a tunable resistor by providing variable output values of resistance when said switch positions in said resistor ladder network are varied.