resistor ladder

A resistor ladder is an electrical circuit made from repeating units of resistors, in specific configurations. An R–2R ladder configuration is a simple and inexpensive way to perform digital-to-analog conversion (DAC), using repetitive arrangements of precise resistor networks in a ladder-like configuration. A string resistor ladder configuration implements the non-repetitive reference network. History A 1953 paper "Coding by Feedback Methods" describes "decoding networks" that convert numbers (in any base) represented by voltage sources or current sources connected to resistor networks in a "shunt resistor decoding network" (which in base 2 corresponds to the binary-weighted configuration) or in a "ladder resistor decoding network" (which in base 2 corresponds to R–2R configuration) into a single voltage output. The paper gives an advantage of R–2R that impedances seen by the sources are more equal. Another historic description is in US Patent 3108266, filed in 1955, "Signal Conversion Apparatus".