In IC technology all resistor materials have an associated temperature coefficient. Most commonly, resistors are made from polysilicon, diffusion of various kinds and metal. The most common of these resistors is poly and diffusion. In certain applications a temperature independent resistor may be required. In order to do this one has to search the technology properties to see if there are resistor materials in the technology that can provide (1) An appropriate sheet resistance and (2) opposite temperature coefficients. Almost all semiconductor technologies provide this. Once the materials are established a first order temperature independent resistor may be synthesized as shown in a recent report released by Signal Processing Group Inc. This report may be found at:
http://www.signalpro.biz>engineer’s corner.