Analysis and design of monolithic resistors with a desired temperature coefficient using contacts

A technique for implementing monolithic resistors with a desired temperature coefficient (TC) over a wide temperature range is introduced. A typical monolithic resistor consists of a core resistive layer terminated with contact layers on each end. In a typical process, there are core resistive layers that have TCs with opposite sign of that of the contacts. The authors propose to take advantage of this property and distribute a certain number of contacts across the core resistor to achieve a desired overall TC for monolithic resistors. This TC can be negative, zero or positive. The methodologies for designing such resistors are presented. As a proof-of-concept, several resistor structures have been designed and implemented in a 0.13 μm complementary metal-oxide semiconductor technology. The simulation and measurement results over the temperature range of 25-200°C confirm the validity of the proposed technique.