weightedresistor

A weighted resistor is a type of resistor used in electronic circuits where its resistance value is proportional to a specific weighting factor. This concept is often employed in applications requiring a variable resistance that is not linearly controlled, but rather follows a defined, non-uniform scaling.

The primary use of weighted resistors is in analog-to-digital converters (ADCs), particularly in resistor ladder networks. In a binary-weighted resistor ladder, each resistor’s value is an exact power of two relative to the smallest resistor. For example, if the smallest resistor is R, the next would be 2R, then 4R, 8R, and so on. This arrangement allows for the conversion of an analog voltage into a digital output where each bit corresponds to a specific weighted contribution of the input voltage.

The advantage of using weighted resistors in ADCs is their relative simplicity of design and understanding. However, they can suffer from inaccuracies due to component tolerances, especially as the number of bits increases, leading to large variations in resistor values. Achieving precise ratios for higher bit counts can be challenging and expensive. Alternative designs, such as R-2R ladders, are often preferred for their improved precision and reduced component count for a given number of bits. Despite these limitations, weighted resistors remain a fundamental concept in understanding digital-to-analog conversion.