Logarithmic resistor ladder

Posted on Feb 6, 2014

A logarithmic resistor ladder is an electronic circuit composed of a series of resistors and switches, designed to create an attenuation from an input to an output signal, where the logarithm of the attenuation ratio is proportional to a digital code word that represents the state of the switches. The logarithmic behavior of the circuit is its ma

Logarithmic resistor ladder
Click here to download the full size of the above Circuit.

in differentiator in comparison with digital-to-analog converters in general, and traditional R-2R Ladder networks specifically. Logarithmic attenuation is desired in situations where a large dynamic range needs to be handled. The circuit described in this article is applied in audio devices, since human perception of sound level is properly expressed on a logarithmic scale. As in digital-to-analog converters, a binary word is applied to the ladder network, whose N bits are treated to represent an integer value according the relation: This example circuit is composed of 4 stages, numbered 1 to 4, and an additional leading Rsource and trailing Rload. Each stage i, has a designed input-to-output voltage attenuation ratioi as: The different stages 1. N should function independently of each other, as to obtain 2N different states with a composable behavior. To achieve an attenuation of each stage that is independent of its surrounding stages, either one of two design choices is to be implemented: constant input resistance or constant output resistance. The circuit as depicted above, can also be applied in reverse direction. That correspondingly reverses the role of constant-input and constant-output resistance equations. Since the stages do not influence each other`s attenuation, the stage order can be chosen arbitrarily. Such reordering can have a significant effect on the input resistance of the constant output resistance...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    16 watt amplifier
    touch sensor switch using inverters
    Computer Microphone
    pcb fabrication Feasibility Question and Advice on CAD software
    FET applications
    Closed-loop three-phase multivibrator
    Ultra High Sensitivity Metal Detector Circuit