A geometric ladder circuit produces a transfer function having substantially uniform steps measured in dB. Where the ladder has a plurality of substantially identical resistor rungs of a first resistance, one stile that is a conductor connecting the rungs, and another having a series of substantially identical resistors of a second resistance, then for identical currents injected at different rungs, the output signal at an end of the ladder is attenuated by a number of substantially equal steps, one for each rung between input and output. For a ladder with a base rung R, an output at an end opposite the base rung, stile resistors of resistance .alpha.R, and other rungs all of resistance (1+(1/.alpha.))R, the step size is 20 log.sub.10 (1+.alpha.).
CROSS REFERENCE TO RELATED APPLICATION
This claims the benefit of copending, commonly-assigned U.S. Provisional Patent Applications Nos. 60/695,341 and 60/776,156, filed Jun. 30, 2005 and Feb. 22, 2006, respectively, each of which is hereby incorporated herein by reference in its respective entirety.
A geometric ladder circuit produces a transfer function having substantially uniform steps measured in dB. Where the ladder has a plurality of substantially identical resistor rungs of a first resistance, one stile that is a conductor connecting the rungs, and another having a series of substantially identical resistors of a second resistance, then for identical currents injected at different rungs, the output signal at an end of the ladder is attenuated by a number of substantially equal steps, one for each rung between input and output. For a ladder with a base rung R, an output at an end opposite the base rung, stile resistors of resistance .alpha.R, and other rungs all of resistance (1+(1/.alpha.))R, the step size is 20 log.sub.10(1+.alpha.).
